Retrofit of Lithuanian large concrete panel buildings with prefab timber elements

Master’s Thesis in Energy Efficient and Sustainable Building (Building Technology specialization):

Retrofit of Lithuanian large concrete prefabricated timber elements

Chair: Technische Universität München Chair for Timber Structures and Building Construction Univ.-Prof. Dr.-Ing. Stefan Winter

Supervisors: Dipl.-Ing. Stephan Ott M.Sc. Klaus Mindrup Author: Dominykas Marcinonis Submission date: 30. November 2015

panel buildings with

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Kurzfassung

Kurzfassung In der vorliegenden Masterthesis ist eine rationale Strategie für die Plattenbausanierung mit vorgefertigten Holzelementen (TES EnergyFaçade) in Vilnius (Litauen) entwickelt. Etwa 40% der heutigen Bevölkerung in Vilnius wohnt in solchen Gebäuden (Baujahr 1959-1993), wobei über 97% aller Wohneinheiten Eigentumswohnungen sind.

Mangelhafte Grundrissfunktionalität, monotonische und zum Teil verfallene Fassaden, und veraltete Wohnsiedlungsstruktur sind verantwortlich für die fehlende Attraktivität der Plattenbauten. Da die Plattenbausiedlungen fast zentral gelegen sind, führt solche Situation zu einer raschen Zersiedlung. Darüber hinaus sind die hohen Heizkosten eine ernste finanzielle Belastung für einen großen Teil der Bewohner. In der heutigen Praxis der energetischen Modernisierung wird nur dieses Problem berücksichtigt. Daher können die sanierten Gebäude die funktionelle Neubauqualität nicht erreichen.

Unter Berücksichtigung der Rechercheergebnisse wurde ein vorgefertigtes modulares Sanierungssystem vorgestellt. Dessen Anwendbarkeit und Effizienz wurde durch die Detailierung des Sanierungsentwurfs für einem weitverbreiteten Plattenbautyp 1-464LI-18/2 (5-geschoßig, 30 Wohneinheiten) nachgewiesen.

Das System macht das Gebäude anpassbar an die wechselnden Bedürfnisse der Bewohner. Dafür sind die Raumerweiterungen, Fenster und das Lüftungssystem als Sanierungsmodule konzipiert.

Sie haben Basis- und Verbesserungsversionen, die man beliebig mit einander tauschen kann. Die Sanierungsmodule sind in den einzelnen Wohnungen oder in den bestimmten Wohnungsgruppen installierbar. Die Kombination der Basisversionen der Module orientiert sich meistens an der technischen Gebäudequalität, erfüllt die heutigen Energiestandards und spart damit etwa 60% der Endenergie für die Heizung und Warmwasseraufbereitung. Die Sanierungspakete mit den verbesserten Modulen passen die Grundrisse den heutigen Wohnstandards an und erreichen den Passivhausstandard für die Sanierung EnerpHit. Mit Hilfe der kombinierten digitalen und physischen Methoden lässt sich eine höhere Gebäudequalität mühelos und Schritt-für-Schritt erreichen. Dadurch passt man das Haus automatisch den Bedürfnissen und finanziellen Möglichkeiten der Bewohner während des Gesamtlebenszyklus des Gebäudes an. Damit kann Energieeinsparung nicht nur im gesamten Gebäude sondern auch in kleineren Abschnitten realisiert und individuelle Fassadenansichten in jedem Einzelfall erzeugt werden. Die Eigentümer richten den Entwurf der Sanierung individuell ein.

Dafür benutzen sie den Sanierungskonfigurator, der die technischen und ökonomischen Aspekten jeder Sanierungsmodulkombination für die einzelnen Wohnungen zeigt. Die erforderliche physische Flexibilität und Konsistenz der Bauelemente werden durch ihre Vorfertigung gewährleistet. Die serielle Produktion ist wegen der standardisierten Geometrien der Plattenbauten und durch die Verwendung der einstellbaren großformatigen Fassadenelemente aus Holz (TESElementen) machbar. Neben den typischen Vorfertigungsvorteilen wie die Material- und Kosteneinsparung, Arbeitsqualität und minimierte Störung der Einwohner während der Bauarbeiten, fördert das vorgeschlagene System die Individualität der Einwohner und motiviert sie gleichzeitig zum Kooperation, was zur Entstehung der starken Gemeinschaft beitragen könnte.

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Abstract

Abstract In the master‟s thesis a reasonable retrofit strategy for standardized concrete apartment blocks in Vilnius (Lithuania) with prefabricated timber-frame elements (TES EnergyFaçade) is developed.

Nowadays about 40% of the Vilnius‟ population is living in these buildings (construction year 19591993), where 97% of the apartments are a private property of the residents. The poor floor plan layout functionality, monotonous and partly deteriorated exterior and obsolete socialist large-scale urban structure cause their bad image in the society. The unattractiveness of these almost central located mass-housing estates leads to a rapid urban sprawl. Moreover, the high heating bills constitute a serious financial burden for a significant part of the residents. The current local retrofit practices focus mainly on the later problem. As a result, the retrofitted buildings still do not reach the quality of the new ones.

Basing on the findings of the research, an industrial modular retrofit system is proposed and its feasibility and efficiency proved by detailing a retrofit design for a popular concrete panel building type 1-464LI-18/2 (5-storey, 30 apartments).

The system makes the building adaptable to the changing residents‟ needs. For this, the space extensions, windows and ventilation system are conceptualized as retrofit modules: these have basic and advanced versions, which can be optionally replaced by each other and implemented either in single apartments or in groups of them. The combination of the basic module versions focuses mainly on the technical quality of the building and makes it conform to the today´s energy standards, saving over 60% of the final energy for space heating and DHW. The packages of the most advanced modules adapt the layouts to the contemporary living space requirements and potentially reach the Passive House standard for the refurbishment EnerPHit. Due to the combined digital and physical methods the higher building quality levels can be easily reached step-by-step, adapting to the individual needs and financial capabilities of the residents over the life-cycle. In this way the further overall energy savings of the house are minimally blocked and a distinctive façade image is created in every particular case. The residents digitally customize the final retrofit design on their own by using a retrofit configurator, which shows the economic and technical aspects of each module combination for separate flats. The required physical flexibility and consistency is achieved due to the prefabrication of the main building elements. The proposed adjustable self-bearing insulated facade panels (TES) and the standardized nature of the analyzed buildings make a mass-production viable. The benefits of the suggested retrofit approach are not limited to the general prefabrication benefits like time, cost and material savings, workmanship quality and minimal disturbance of the residents. The system embraces the individuality of the residents, motivates their cooperation and thus may contribute to the emergence of a strong community.

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Foreword

Foreword The master‟s thesis is the final phase of the Master in Energy Efficient and Sustainable Building at the Technische Universität München. The thesis deals with the retrofit of large concrete panel multi-apartment buildings in Lithuania. The topic is of high relevance for the public in Lithuania as well as in the other countries, as the problems with these blocks are obvious and big stateinvestments are currently made in the refurbishment sector. In the work a rational retrofit strategy for these concrete buildings is developed, which should demonstrate the so far unrevealed retrofit potentials through versatile modular solutions, contributing to the overall knowledge base about the topic.

Acknowledgements: Dipl.Ing Stephan Ott and M.Sc Klaus Mindrup (Chair for Timber Structures and Building Construction, Technische Universität München) – supervision of the master„s thesis.

Prof. Dr. habil. Josifas Parasonis (Department of Achitectural Engineering, Vilniaus Gedimino Technikos Universitetas) – help on investigating the large panel building stock.

Prof. Dr. habil. Vytautas Martinaitis and Prof. Dr. Giedrius Šiupšinskas (Department of Building Energetics, Vilniaus Gedimino Technikos Universitetas) – help on analyzing the local retrofit practices and the existing building systems.

München, 30. November 2015

Dominykas Marcinonis

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Glossary

Glossary Large concrete panel building/block (also large panel building, prefab concrete building) – a standardized building, constructed from mass-produced prefab concrete panels (walls and slabs).

Common construction type in Western Europe in the post-war period and in the former Eastern Bloc in 1955-1993.

Large panel building series – a standardized collection of large panel buildings, which have uniform structural and functional properties, are designed according to the same standard and their elements can be manufactured with the same devices. Each series includes building types of different sizes and configurations.

Large panel building type – a single building project, repetitively used to construct completely identical large panel buildings.

Socialist housing estate (also soviet district, mass-housing estate) – a large-scale uniform urban structure for residential purposes. Beside the residential large panel buildings also public facilities like schools and clinics are included. Connected to the public transport network. Usually developed at a one stroke on previously not urbanized fields.

Condominium – an individually owned apartment in an apartment house, where the other flats are also individually owned. Use of land access to common facilities in the piece such as hallways, heating system, elevators, and exterior areas are executed under legal rights associated with the individual ownership. These rights are controlled by the association of owners that jointly represent ownership of the whole piece (house).

U-value (also U-factor) – heat transmission coefficient. It defines an energy flux through a 1 m2 of the particular construction, when the temperature difference across the construction is 1 K. The lower the value is, the better the insulation ability of the construction.

Air exchange ratio n – defines, which portion of the indoor air is exchanged within one hour.

While n defines the air exchange in the natural conditions, the n50 refers to the air exchange ratio on the artificially increased 50Pa pressure between indoors and outdoors. The first value is used for definition of ventilation. The second value is normally higher and expresses the air-tightness of the building.

Daylight factor (DF) – defines the portion of the unobstructed daylight, which falls on the shaded surfaces. Thereby the sky is assumed as a single daylight source; therefore the orientation and the daytime are irrelevant parameters for daylight factor calculation.

Energy demand – estimated, predicted energy amount for a particular purpose Energy consumption – real, measured energy use for a particular purpose

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Glossary

Primary energy – an initial chemical, mechanical, light or nuclear energy, which lies in the energy sources and has not been subjected to any conversion or transformation process. Depending on its origin, the primary energy may be renewable (wind, sun) or not renewable (fossil fuels). The various energies may contain both these components. However, for the environmental assessment of the products or processes normally only the not renewable part of the primary energy is used.

Gross final energy consumption – energy commodities delivered for energy purposes to final consumers (industry, transport, households, services, agriculture, forestry and fisheries), including the consumption of electricity and heat by the energy branch for electricity and heat production and including losses of electricity and heat in distribution and transmission (Renewable Energy Directive 2009/28/EC).

Final energy consumption – covers all energy supplied to the final consumer for all energy uses.

It is usually disaggregated into the final end-use sectors: industry, transport, households, services and agriculture.

Useful energy – refers to the portion of the final energy, which is actually used by the end-user for a particular purpose, for instance - light energy of the light bulb.

Building information modeling (BIM) - a digital representation of physical and functional characteristics of a facility (2).

Building information model (also parametric building model) – a shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition (2). openBIM - a universal approach to the collaborative design, realization and operation of buildings based on open standards and workflows. openBIM is an initiative of the international organization buildingSMART (2).

Industry Foundation Class (IFC) - a common data schema (IFC) that makes it possible to hold and exchange relevant data between different software applications (2). Developed by buildingSMART, bases on ISO 16739 Passive house – a building, for which thermal comfort (ISO 7730) can be achieved solely by postheating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air (3). The concept is developed

by Passivhaus Institut (PHI).

EnerPHit - PHI-Certificate for refurbishment of existing buildings (3). Two ways of certification possible: based on the space heating energy demand or on the Passive House components.

PHPP – Passive House Planning Package. Excel-based energy analysis tool.

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Glossary

TFA – treated floor area, as defined by the Passive House standard and used in the calculations with PHPP. AFA – apartment floor area.

Retrofit - providing something with a component or feature not fitted during manufacture or adding something that it did not have when first constructed (4).

Refurbishment - implies a process of improvement by cleaning, decorating, and re-equipping. It may include elements of retrofitting (4); in the study used a synonym for retrofit.

Façade panels (TES-elements) – large prefabricated timber-frame elements, which are mounted on front of the façade during the retrofit. Depending on the level of the prefabrication, the panels may be isolated and have a final exterior finish. They can also include windows, building systems and other elements.

Retrofit modules – variable retrofit measures like windows, space extensions and ventilation.

They have basic and advanced versions, which can be replaced with each other and implemented either in a single apartment or in the groups of them.

Initial retrofit – the first retrofit phase, when the proposed retrofit system is applied for the whole building. Thereby a common approval of the majority of the residents is needed; the financial state support fully availed. Afterwards the further individual retrofits are enabled.

Basic retrofit (basic retrofit package/combination) – represents the minimal building quality due to the proposed retrofit system, as it includes only the basic versions of the retrofit modules.

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Table of contents

Table of contents 1 Introduction ....................................................................................................................... 1 2 State of the art ................................................................................................................... 3 2.1 Historic background .................................................................................................... 3 2.2 Urban and socio-demographic aspects ....................................................................... 4 2.3 Energy sources........................................................................................................... 7 2.3.1 District heat ....................................................................................................... 7 2.3.2 Electricity ........................................................................................................... 9 2.4 Building analysis: 5-storey 30 apartment house of type 1-464LI-18/2 ....................... 10 2.4.1 Layout ............................................................................................................. 10 2.4.2 Constructions .................................................................................................. 18 2.4.3 Building systems ............................................................................................. 27 2.4.4 Energy analysis ............................................................................................... 32 2.4.5 Financial consequences due to the heating bills for the residents.................... 39 2.5 Legal requirements ................................................................................................... 41 2.5.1 Energy ............................................................................................................. 41 2.5.2 Fire safety ....................................................................................................... 42 2.6 Current retrofit practices in Lithuania ........................................................................ 43 2.6.1 Energy retrofit program .................................................................................... 43 2.6.2 Typical retrofit projects .................................................................................... 44 2.6.3 Investment plan ............................................................................................... 45 2.6.4 Energy retrofit of large panel building series 1-464LI in Vilnius ........................ 48 2.6.5 Urban revitalization projects ............................................................................ 50 2.7 Retrofit examples abroad .......................................................................................... 51 2.7.1 Modifications of large panel buildings in Leinefelde, Germany ......................... 51 2.7.2 Transformation of a housing block in Paris, France ......................................... 52 2.7.3 Energy retrofit with prefabricated timber elements in Augsburg, Germany ....... 53 2.7.4 ELEMENTAL social housing project in Iniqueqe, Chille ................................... 54 2.8 Lithuanian construction sector .................................................................................. 55 2.8.1 Prefab timber construction ............................................................................... 55 2.8.2 Digital construction .......................................................................................... 55 2.9 SWOT analysis ......................................................................................................... 56 3 Retrofit with prefabricated timber elements...................................................................... 58 3.1 Targets ..................................................................................................................... 58 3.2 Method ..................................................................................................................... 59 3.2.1 Modularity ........................................................................................................ 59 3.2.2 Workflow ......................................................................................................... 60 3.2.3 Tolerances ...................................................................................................... 65 3.2.4 Façade panel size definition ............................................................................ 67 3.2.5 Static scheme .................................................................................................. 68 3.3 Typical retrofit project ............................................................................................... 72 3.3.1 Preliminary energy calculations ....................................................................... 72

Lehrstuhl für Holzbau und Baukonstruktion Master‟s thesis „Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements“ Table of contents

4 5 6 7 8

3.3.2 Layout ............................................................................................................. 74 3.3.3 Constructions .................................................................................................. 87 3.3.4 Building systems ........................................................................................... 113 3.3.5 Preliminary price estimation ........................................................................... 123 3.4 Retrofit configurator – results .................................................................................. 125 3.4.1 Configuration ................................................................................................. 125 3.4.2 Building level ................................................................................................. 128 3.4.3 Apartment level ............................................................................................. 135 3.4.4 Façades ........................................................................................................ 154 Conclusions ................................................................................................................... 156 Bibliography .................................................................................................................. 158 Table of Figures ............................................................................................................ 162 List of tables .................................................................................................................. 168 Appendix ....................................................................................................................... 170 8.1 Final energy consumption ....................................................................................... 170 8.1.1 Fuel prices ..................................................................................................... 170 8.2 Large panel building series – state of the art .......................................................... 171 8.2.1 Location......................................................................................................... 171 8.2.2 Sociocultural and functional quality................................................................ 172 8.2.3 Technical quality............................................................................................ 179 8.2.4 Economic quality ........................................................................................... 181 8.2.5 Evaluation ..................................................................................................... 182 8.4 Energy balance....................................................................................................... 184 8.5 Typical retrofit projects............................................................................................ 185

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 1. Introduction

1

Introduction

Fig. 1 Mass-housing estates: left – district Lazdynai in Vilnius (Lithuania), year 1966; right – district Vällingby in Stockholm (Sweden), year 1953 (5) The multi-apartment blocks from the socialist period constitute a significant share in the total building stock of Lithuanian and other Eastern European cities. These buildings can be characterized by a standardized minimalistic design, an extensive use of mass-produced concrete panel constructions and modernistic, large-scale urban structures. In Lithuania this mass housing concept was firstly and most widely implemented in the capital city Vilnius, where population doubled from 236100 in 1959 to 576000 in 1989 (6). As a result, today about 40% of Vilnius‟ residents live in concrete multi-apartment blocks (6), (7).

3%

10%

single and double family Multi-family (large panel) Multi-family (other)

47% 40%

Other

Fig. 2 Building stock in the city of Vilnius (6), (7) Today the socialist housing estates form a twofold problem. Firstly, the monotonous and deteriorated buildings and their environment do not suit to the modern living standards and are unattractive for the newcomers. This leads to an intense urban sprawl, which is particularly visible in Vilnius, a quite dynamic and growing city, where massive shrinkage and ageing of the population in the almost central located soviet districts is observed, followed by a rapid growth of the remote areas around the city boundary. The chaotic low density urban structure boosts the energy demand for transport and determines an irrational use of the available resources (8). The second problem is a high heat energy consumption of the prefab buildings, which causes high CO 2 emissions and makes the residents very sensitive to the rising energy prices. The resulting heating bills are a serious financial burden for the majority of the residents (9). The government is even forced to at least partly refund utility costs for about 6% of the total population (9).

1

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 1. Introduction

Lithuania

Vilnius

Population (6)

2 902 832

542 990

Area

65 300 km²

401 km²

Population density

44 pers/km²

1354 pers/km²

Population change 2011-2015 (6)

- 4,0 %

+ 1,6 %

Average age (6)

42,0

38,0

Ethnics (6)

Lithuanians: 86,7 %

Lithuanians: 57,8 %

Poles: 5,6 %

Poles: 17,8 %

Russians: 4,8 %

Russians: 14,0 %

74 % (73)

Vilnius region (6):

Lithuania Vilnius

GDP/capita in reference to the EU-28 average

106% (40% of the total national GDP)

Fig. 3 Key information about the country and the capital city Facing such problematic, the state treats the heat energy consumption as a core problem, and implements the Program for the Refurbishment of Multi-Apartment Buildings, which accords with the European Directive of Energy Efficiency. Its target group is the multi-apartment buildings, which had been constructed until the year 1993 (9). The key-objectives of the program for the year 2021 are to reduce the total estimated heat energy demand of these buildings by at least 20% (1000 GWh) and to decrease their total annual CO2 emissions by at least 230 000 t, in reference to the year 2005 (9). In order to achieve this goal 4000 state funded energy retrofit projects of old multifamily buildings should be completed (9). However, the initiatives of the public authorities are particularly restricted by the fact, that all the apartments in these houses are individually owned by their residents.

It is questionable, whether the pure energy retrofits of the mass-constructed buildings are sufficient to regain the real estate attractiveness (8). If not, the urban sprawl might proceed and the achieved heat energy savings in the building sector could be compensated by growing energy and resource consumption in transport and industry, additionally wasting the high state investments (8).

Therefore, an in-depth analysis of the existing conditions is performed in the first part of this thesis.

Firstly, urban and socio-demographic situation of the soviet districts in Vilnius is investigated.

Secondly, a representative large panel building type is selected and inspected in detail.

Furthermore, the building regulations, current retrofit practices in Lithuania and abroad, and the existing situation in the construction sector is assessed. The analytical part is concluded with a final SWOT (strengths, weaknesses, opportunities and threats) analysis, which helps to identify the retrofit potentials and shape its concept.

In the second section a rational retrofit strategy for the already analyzed large panel building type is developed. The present socio-demographic structure in the socialist housing estates is perceived as a key driving factor for the successful transformation of the separate monotonous blocks, thus turning the private ownership of the separate apartments to advantage. The standardized geometries of the discussed buildings suggest the use of prefabricated retrofit systems, therefore the principles of the façade energy retrofit system TES EnergyFaçade (10) are 2

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

applied and further developed. Due to the modularity and detachability of the prefab components of the retrofit system, individual step-by-step improvements of the building functionality and energy performance can be allowed, additionally generating diverse exterior image. A key-objective in this section is to create a catalogue of tangible detail solutions for such modular system, evaluate their environmental and economic consequences, and provide recommendations for different residents groups. Thereby the way of presentation should be considered, so that the information would be understandable for the users without specific knowledge, like the majority of the residents of the prefab housing blocks are.

The targets of the study are the following:

2 2.1

-

Explore the existing conditions regarding the large panel buildings, recognize the primary factors, which are causing the current situation and identify the retrofit potentials and eventual external effects.

-

Embrace the individuality of the residents, involve them into the design process and turn the presence of the condominiums to advantage, unobtrusively provoking a gradual emergence of the community.

-

Create a retrofit design of a representative type of large panel building which could show, whether the highest energy efficiency standards and the attractiveness levels such as these of the new construction can be achieved.

-

Emphasize the perspectives for the innovative and sustainable construction, design and process management methods in the Lithuanian refurbishment sector.

State of the art Historic background

The spread of standardized construction in the Lithuania had political, demographical as well as economic reasons. In 1940 -1990 Lithuania was under the occupation by the Soviet Union. In the early 50‟s there started a rapid industrialization, followed by huge urbanization rates. While using old construction methods, the state could not afford to provide the incomers with new dwellings. In 1955 the Central Committee of the Communist party of the Soviet Union and Council of Ministers carried a resolution “On the elimination of extravagances in design and construction”, where standardized projects in minimalistic modernistic style were propagated, as the fastest and the most economical solution to the problem. The design and construction methods were taken from the Western countries during the Soviet delegation study trips (5). The use of the mass-produced concrete panel structures enabled a faster and more reliable construction and was clearly advantageous against the typical masonry construction (5). In contrast to the Western countries, where the drawbacks of such architecture were soon noticed (demolition of the Pruitt-Igoe district), its era in the former Eastern Bloc lasted until the collapse of the communist system in the 90‟s (11).

3

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.2

Urban and socio-demographic aspects

Large panel buildings are sorted in series. A series is a standardized collection of buildings, which have common structural and functional properties, are designed according to the same building standard and their elements can be manufactured with the same devices. Each series includes building types of different sizes and configurations. The 4 main series of large panel houses in Vilnius are shortly described in the Table 1. A detailed assessment can be found in the Appendix 8.1.

Table 1 Large panel building series in Vilnius

Series Years of construction Share in total households in Vilnius (7) Location (8)

Population density (12) Demographic structure (12)

1605 1959-1961

1-464A 1961-1966

1-464LI 1966-1978

120V 1978-1993

0,8%

5,6%

16,4%

17,2%

Very good: High functional mixture, lack of green zones, good social infrastructure, good accessibility, within planned revitalization territories 6000-8000 people/km²

Very good: Moderate to high functional mixture, lots of green zones, good social infrastructure, good accessibility, within planned revitalization territories 12000-16000 people/km²

Good / very good: Low to moderate functional mixture, lots of green zones, good social infrastructure, good accessibility, partly within planned revitalization territories 8000-14000 people/km²

Satisfying / good: Low to moderate functional mixture, lack of green zones, moderate social infrastructure, poor accessibility

-14%

-2%

-12%

-11%

12000-16000 people/km²

Vilnius average:

Population change 20012011 (12) Vilnius: -3%

4

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

City core

Fig. 4 Large panel buildings in the context of the city of Vilnius Because of specifics of mass construction and plan economy in the USSR, the separate large panel building series are clearly distributed in the city, as shown in the map (Fig. 4). Until 1965 the large panel buildings had been constructed on the free sites within the existing urban surroundings (13). Therefore, the oldest building series (1605, 1-464A and partly 1-464LI) are located in quite dense and heterogeneous neighborhoods near to the city center. These territories falls within the boundaries of the city core (Fig. 4), where the Vilnius city municipality plans lots of urban revitalization projects until the year 2023 (8). Since 1965 urban development has moved into another level: vast empty areas around the city were completely urbanized and new homogenous soviet districts emerged (13). Each district (up to 30000 residents) consists of few sub-districts (5000-15000 residents). Each sub-district has a school, kindergarten and a shop. Additionally, local cultural centers and health facilities were designed for districts. In contrast to good social infrastructure, the soviet housing estates lack of services, which are found in central areas (shops, cafes, offices) (14).

During the last decade the population of Vilnius has remained stable and a minor growth is predicted till the year 2023 (8). However, the city is suffering from an intensive urban sprawl. In 5

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

period between the year 2001 and 2011, the rural regions around the city has grown by 40% and more, while the areas in the high density city core were shrinking, as shown in the Fig. 5. Near the city center situated soviet districts are especially affected by this worrying trend, as they lost more than 10% of their population in ten years (6). Because mostly younger residents are moving, the remaining population in these regions is getting old. The share of seniors (over 65 years old) in the older districts is already considerably higher than the average of Vilnius (22-25% and 15%, respectively), while the share of the young people is lower (12). This problematic is especially noticeable in the homogeneous districts of the series 1-464LI (see Table 1).

City core

Fig. 5 Urban sprawl in Vilnius in 2001-2011 (6) This shrinkage has few reasons. Firstly, after recovery of independence in 1990 all flats were privatized by their users, which had no experience and now understanding on how to maintain the common property together. Moreover, no regulation mechanisms for the maintenance of buildings and their surroundings were developed – every decision requires a common agreement of the majority of the owners, what is difficult in reality (11). It resulted in slow deterioration of building stock. Secondly, in soviet times the middle class was the main social group there - other dwelling alternatives were then simply not available (11). Due to the transition to market economy and an economic growth after 1990, the supply of new flats with more comfortable layouts and more diverse and esthetic environments slowly grew. People with higher incomes could then choose where to live and started leaving unattractive blocks. Furthermore, in Lithuanian society renting a flat can be perceived only as a temporary solution for living. Therefore, it is no wonder that young families prefer to invest their money in newly constructed buildings, rather than in slowly deteriorating soviet houses. Additionally, the large-scale urban structure of these areas seems 6

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

obsolete: it lacks private outdoor space; big open yards hinder the generation of smaller closer trustworthy neighborhoods, what is interconnected with safety issues. This deters young people from moving to these blocks (11). The resulting shrinkage of the middle working class means that the rest residents have less financial resources for the maintenance and improvement of the buildings and their environment. This accelerates further technical and esthetical deterioration, which can finally end with numerous social problems, like it happened in Western countries in 70‟s (demolition of Pruitt–Igoe district, USA). The possibility of such scenario is growing, but due to the wide spread of such housing estates, it would cause much more serious economic and ecological problems (11).

For the further analysis series 1-464LI was chosen, as there are a large number of such buildings and they are situated in quite convenient locations. The discussed demographic structure in these districts and their poor general condition was perceived as a challenge.

2.3

Energy sources

For the large panel buildings two forms of energy are relevant: district heat and electricity. On the energy generation methods and used fuels depends two most important environmental indicators: not renewable primary energy conversion factor fPR,n and the conversion factor for the CO2 emissions MCO2 . Due to the multiplication of these factors with the final energy consumption values of the analyzed buildings, the total primary energy demand and the CO 2 emissions during the building‟s operation can be calculated. In addition to the environmental indicators, also the existing and planned future energy prices are assessed.

The Lithuanian energy strategy is called National Strategy on the Energy Independency (15), as one of the driving factors for the use of local renewable energy sources (RES) is a very high share of imported energy. The RES-portion in the gross final energy consumption should be not less than 23% in the year 2020 (15), which is likely to be exceeded. Future tendencies for the discussed environmental indicators and the energy prices are basing on the planned energy mix.

2.3.1

District heat

All large panel buildings, as well as the most of other houses in Vilnius, are provided with heat from a district heating system. The district heat sector plays an important role in the national energy strategy. According to the National Program for the District Heat Sector Development (16), the main target for this field until the year 2021 is to reduce the heat energy prices and negative environmental impacts by prioritizing the local renewable energy sources (RES) like biomass, biogas and waste. The average Lithuanian heat energy mix is shown in the Fig. 6 (left). On the Lithuanian average more than 40% of district heat is produced using the local renewables (6). This figure has radically increased since the last decade and should exceed 70% until the year 2021 (16). Such an extensive use of the local biomass is possible, because its estimated annual resources in 2021 (~20,3 TWh (16)) clearly exceed the predicted district heat demand (~8 TWh (16)). The heat production in combined heat and power (CHP) plants is especially propagated.

However, the main fuel in the biggest heat energy consumer Vilnius is natural gas and only less 7

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

than 10% of heat energy is produced from biomass (year 2013 (16). The most of the heat energy there is generated in CHP plants. In order to achieve the targets of the energy strategy, new biomass and waste based cogeneration plants are planned (16). Information about the actual primary energy and CO2 emission conversion factors of district heat producers in Vilnius is currently unavailable. As Vilnius is the biggest district heat consumer, the national average values for the district heating are applied according to the building technical regulation STR 2.01.09:2012: fPR,n = 1,30; MCO2 = 0,26 kgCO2/kWh (17). In comparison, the biomass-based district heat in other Lithuanian cities have the values of about 0,20 and 0,015 kgCO2/kWh, respectively (17).

Considering the aims of the national energy strategy, the assumed values of environmental indicators in Vilnius are going to change positively in the near future.

District heat price variation in Vilnius and Lithuania is shown in the Fig. 6 (right). During the year 2005-2013 the natural gas prices increased about 4 times, which resulted in almost tripled district heating prices in Vilnius. In 2014 a LNG terminal was built and thus a dependency on a single gas importer was dissolved, which also reduced the district heat prices. Additionally, due to the use of the local biomass, which costs about two times less than the natural gas (18), a 20% district heat price reduction in 2021 in comparison to the year 2013 is aimed (16). Furthermore, the investments on the local fuels circulate in the local economy and create new jobs – the positive effect of the RES-development in the Baltic region is the biggest in the EU (19). However, low energy prices reduce the economic effect of the implemented energy efficiency measures. Therefore, in this point of view, the low-price scenario can be assumed as a worst-case scenario. Such low district heat price increase scenario until the year 2050 is created basing on the fuel price prognosis ( (18), Appendix 8.1.1) and the rising share of the biomass in the total heat energy mix. It is predicted, that the biomass price rises faster than the natural gas price, but still remains lower. As shown in the Fig. 6, the district heat prices may rise about 3-4% annually. A constant 3% heat price increase is assumed in further analysis, as a worst-case scenario for the energy efficiency measures.

30%

0,04

20%

0,02

10%

0,00

0% 2048

0,06

2044

40%

2040

50%

0,08

2036

0,10

2032

60%

2028

70%

0,12

2004

0

80%

0,14

2024

2

0,16

2020

4

90%

2016

6

100%

0,18

2012

8 EUR/kWh

District heat, TWh/a

10

0,20

2008

12

Heat plants - fossil

CHP fossil

Share of renewables

2% annual increase

Geothermal

CHP renewable

Low price scenario

3% annual increase

Biomass heat plants

District heat demand

LT Average

Vilnius

Fig. 6 District heat in Lithuania (6): gross consumption and local generation (left); prices (right) 8

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.3.2

Electricity

The Lithuanian electricity mix and gross final consumption is shown in the Fig. 7 (left). After the shutting down of the old nuclear power plant in 2009, about 70% of the required electricity is imported. Although a new nuclear power plant is foreseen in the Lithuanian energy strategy, this initiative is stuck after a disagree-referendum in 2012. Assuming, that the whole imported electricity is produced from the not renewable energy sources, the share of renewables in the whole demand was about 13% in 2014. According to the national energy strategy, this measure must achieve 20% in 2021 (15). In 2014 about 40% of the local electricity production was generated from the RES (similar amounts of wind power, hydropower and biomass CHP plants). The lack of the local electricity generation makes the country dependent on the imports, but could be also realized as a great opportunity for the extensive use of RES, as already emphasized in many studies (20), (19).

The current not renewable primary energy conversion factor for the electricity in Lithuania equals 2,80 and the CO2 conversion factor is 0,60 kgCO2/kWh (21). To compare with, the new German energy regulation EnEV 2016 sets a primary energy factor of 1,8, while the estimated CO 2 emissions in 2014 were 0,569 kgCO2/kWh (22). Due to the further use of RES, the values of these environmental indicators in Lithuania should to decrease in the future.

The variation of the electricity prices is shown in the Fig. 7 (right). Current electricity price for the households is 0,129 EUR/kWh (23). Like for the district heat, the same worst case scenario of 3% annual price increase is assumed in the further analysis.

20

0,40

18

0,35

14

0,30

12 0,25

10

EUR/kWh

Electricity, TWh/a

16

8

6

0,20

4

0,15

2

0,10

0 0,05 Power plants-fossil

CHP fossil

Renewables

Total demand

0,00 2004 2007 2010 2013 2016 2019 2022 2025 2028 2031 2034 2037 2040 2043 2046 2049

nuclear

3% annual increase

LT average

Fig. 7 Electricity in Lithuania (6): gross final consumption and local generation (left); prices (right)

9

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4 2.4.1

Building analysis: 5-storey 30 apartment house of type 1-464LI-18/2 Layout

Fig. 8 Prefab concrete panel building type 1-464LI-18/2 (5/30/2): front and back facades The series 1-464LI includes 5, 9 and 12-storey buildings. A 5-storey block of 1571.9 m² floor area (type 1-464LI-18/2) was selected for the detailed analysis, which later acts as a base for retrofit strategy. The building is composed of two sections, each of them having 15 flats. There are three types of apartments: 2+1A (15 units), 2+1B (10 units) and 4+1 (5 units). On one side the building is attached to the nearby house. This type is chosen because of several reasons. Firstly, this is the smallest building type and the smaller number of the residents simplifies the creation of a tighter community in a house. Secondly, a 5-storey apartment block of 1-464LI is one of the most wide spread building types in Vilnius, as there are more than 400 of them (12). The 5-storey blocks differ only in the number of the sections, so the later developed retrofit solutions can be easily transferred to the longer blocks. Finally, the building consists mainly of the 2-room apartments, which are suitable for various age groups: singles, senior couples or young families with a child.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 9 Type 1-464LI-18/2: Ground floor plan

11

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 10 Type 1-464LI-18/2: Section

12

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 11 Type 1-464LI-18/2: Front façade

Fig. 12 Type 1-464LI-18/2: Back façade

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.1.1 Orientation, site The house and its environment are divided into two sides. The entrance side can be defined as an active part: parking lots and children playgrounds are found there. Two thirds of the kitchens are also oriented to this side. On the other calmer side loggias and most of the living rooms are arranged. The owners of the ground floor apartments (especially elderly women) often set mini gardens in front of their windows, on the both side of the house (see Appendix 8.2.2.1). The orientation of the calmer side of the building is between the west and east, ensuring a sufficient daylighting. Quite mature deciduous trees are often growing in front of the windows, thus providing shading in summer and hindering solar gains in winter. For the distances between the buildings, apparently a 2h rule was used – the minimum distance between the buildings is equal to two heights of the higher building. In case of two 5-storey buildings it is about 30 m.

Fig. 13 Worst case environment scenario and possible orientation range Table 2 Requirements for the daylighting in multi-residential buildings Source Lithuanian building technical regulation STR 2.02.01:2004 Lithuanian hygiene norm HN 98 : 2000 BREEAM UK New Construction (2014): Hea01 Visual comfort DIN 5034-1 E.Grandjean, A.Gilgen: Umwelthygiene in der Raumplanung, 1973

Minimal daylight factor 0,5% in kitchens and living rooms 1,5% on the working plane, for work with 0,5-1,0 mm objects 2% in 80% of the room area 0,9%, in the height of 0,85 m above the floor level, in a half room depth.

DFmax : DFmin = 6:1

View of the sky/ direct sun radiation nd 2 hours of direct sun between 22 March nd and 22 September in at least one room

View of sky in 80% of the room area, in a height of 0,85 m above the floor level (working plane) th 1 hour of direct sun on 17 January in at least one room st

2 hours of direct sun on 21 December in living and children rooms (middle of the room) th 3 hours of direct sun on 8 February in living and children rooms

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

For such built environment, regarded as a worst-case scenario, a solar study was made. Thereby the most shaded flats are considered. These are located on the ground floor, whereby the worst are the apartments of type 2+1A, because their loggias are additional obstacles for the sun radiation. The additional shading by the trees was not considered, because only the dates of cold season were tested, whereby trees have no leaves. Different requirements for the daylighting can be found in various standards and diverse criteria are used to decide, whether the daylight is good (Table 2). The most widely used are view of the sky, sun hours, and the daylight factor.

The portion of the room, where the sky in a height of the work plane is visible, is regulated. As shown in the Fig. 14, the rooms on the ground floor do not pass the threshold of 80%, which is defined in the BREEAM standard. The BREEAM standard is chosen as it is the only international sustainability certification method, which is has been implemented in Lithuania.

Fig. 14 Daylighting scheme of the building and its environment Sun hours were calculated according to the Lithuanian norm STR 2.02.01:2004 (reference date 22nd March) and German standard DIN 5304-1 (reference date 17th January). Three possible orientations of the building (loggias to the south, south-east and west) were compared. Analysis shows that the daylighting in the south oriented flats fulfill only the Lithuanian standard. According to the both norms, a sufficient daylighting on the both sides of the house is achieved only in a West-East oriented building.

Sun hours

7

DIN 5304-1

STR 2.02.01:2004

6

Requirement

5

South

4

North

3

South-East

2

North-West

1

West East

0 17-Jan

22-Mar

Fig. 15 Sun hours in the ground floor rooms of various orientations

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

The illuminance simulations for the daylight factors were performed with Autodesk Render in Cloud Tool. The algorithm Revit uses is called Multidimensional Lightcuts (see Siggraph 2006). Overcast sky conditions were assumed; therefore the orientation and sun hours were irrelevant for the simulations. A common room surface reflection value of 0,50 was selected. The double glazed windows have a light transmittance of 0,70. Daylight factors were calculated in a 0,85 m height above the floor. Again the ground floor apartments were chosen as a worst case scenario. The simulation shows, that the daylight in the ground floor apartments is not sufficient according to the DIN 5304-1 and BREEAM recommendations. Only the kitchens are provided with enough daylight.

However, according to the Lithuanian hygiene norm HN 98 : 2000, the front parts (20-40%) of all rooms are suitable for a work of a middle accuracy, because the daylight factor there is above 1,5%. Logically, rooms with loggias have poorer visual comfort as the ones without loggias.

Fig. 16 Daylight factors on the working plane (0,85 m above the floor level) in the ground floor 2.4.1.2 Barrier-free accessibility Buildings are not barrier-free accessible. Each flat, as well storage chambers in the basement, can be reached only by the stairs, because the ground floor is more than 1 meter above the site level.

According to the former standards of the USSR, up to 5-storey buildings were not provided with elevators.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.1.3 Living rooms and bedrooms Rooms have either 13,9 m² or 17,1 m² floor area. They have decent proportions, so there are usually no problems with the furniture arrangement. According to the standards of the time, 2-room apartment with a kitchen was intended for a 3-member family (13). Hence, the needs for a living room and comfortable bedroom were put in a constant conflict. The quality of a living room is also reduced by a hindered visual connection between the kitchen and other rooms, as they are separated by a corridor.

2.4.1.4 Kitchens Extremely small kitchens (6,51 m²) are the main disadvantage of the layout. It is hardly possible to arrange there all the necessary today‟s kitchen technic together with a decent dining area for the whole family. However, it may still be enough for two persons.

2.4.1.5 Sanitation Sanitation area is extremely small: WC and bathroom has respectively 1,3 m² and 2,0 m² floor area. A bathtub takes almost the whole floor area of the bathroom. Although it is difficult to fit there a wash machine, the bathroom is additionally used as a laundry and drying room.

2.4.1.6 Storage There are built-in cupboards of totally 0,68 m² in the kitchen and in the corridor. These cupboards partly restrict daylight in the entrance area. A 4-room apartment has an additional separate storage room of 2,40 m² floor area. However, the provided storage area is usually insufficient; therefore some goods are also stored in the loggias. Bikes, tires and similar stuff land in the basement, where each apartment has its own 4 m² storage chamber.

2.4.1.7 Loggias Loggias are quite narrow – their width is about 1,20 m. In 30-apartment houses from 70% to 90% of the loggias are individually glazed, in order to get additional warmer and weather protected area.

By doing this, maximum 37% of the façade area is put in this thermal buffer zone, what reduces total energy losses considerably. For this purpose usually a single sheet glazing is used. The individual loggias glazing leads to an extreme diverse, fragmented façade appearance (Fig. 8).

This diversity already became a typical attribute of Lithuanian large panel buildings and competes with the monotonic nature of the building itself. As mentioned above, loggias are also used for storage and as a drying room. Therefore, their recreational function is very restricted.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.2

Constructions

2.4.2.1 Structural scheme

Fig. 17 Static scheme with live loads Exterior walls, interior walls and floor slabs form a quite rigid vertical and lateral load-bearing structure (Fig. 17). T The panels of exterior walls, interior walls and floors are connected to each other by welding reinforcement anchors with additional rebars on the top and bottom of the wall panel (Fig. 19). The connection is covered with in-situ concrete. The joint is assumed as a hinge in the static scheme.

According to the recent master thesis (24), if the design strengths of the elements were assumed, the structure has quite big load reserves even to today‟s requirements, which assume higher safety factors than in former USSR. In order to predict the actual load reserves, the deterioration level of the existing structure must be assessed. This was performed in few detailed studies between 1997 and 2004 (1), (25), (26). Despite big time difference, the results of these surveys do not differ: the 18

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

general structural reliability of the large panel buildings is not threatened, although the balconies, parapet walls and cornices required repair already 18 years ago and today they could be a potential threat to the users (see Appendix 8.2.3). The large panel buildings are expected to stand 80 years without any repair. Considering only the load-bearing elements, the lifetime increases to 135 years. This means, that even in the worst case, the buildings of series 1-464LI should still stand at least 35 years and high load reserves of their structure are probable. In this point of view, their refurbishment is viable and recommended (1).

Fig. 18 bending moments in basement transverse walls (24) However, comprehensive research regarding the existing condition of the panel joints could not be conducted in Lithuania, because this would require at least partial demolition of buildings, which is hardly possible due to the individual ownership of the apartments. Such surveys were conducted in Germany (27), where very similar large panel constructions were also often used (former DDR building series Q3A, IW, P2, QP, WHH). The studies reveal that after a long maintenance the insitu concrete might be completely carbonated, thus removing the effect of a corrosion protection. It can lead to the reduced load-bearing capacity of the reinforcement.

Fig. 19 Joint of interior and exterior walls and floor slab (sections 1-1 and 3-3) 19

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.2.2 Exterior wall

8

6 Fig. 20 Walls panels joint: horizontal and vertical section (28), photo from the outside: 3 – floor slab; 4 – mortar joint; 5 – monolithic concrete, 6 – bitumen hydro isolation; 7 – elastic sealing; 8 – tarred tow; 9 – sealing resin; 10 – cement mortar.

All exterior walls (except self-bearing walls of stairways) are load-bearing and constructed from 300 mm-thick lightweight reinforced concrete panels (28), which consist of three main layers: 1. Exterior layer of fine dense concrete with various surface finishes (~20-30 mm) 2. Middle core layer of expanded clay lightweight concrete (~255-270 mm) 3. Interior face from the fine dense concrete (~10-15 mm) The core layer has both load-bearing and insulating functions. The mass density of expanded clay lightweight concrete varies between 1000 and 1600 kg/m³. The compressive strength ranges from 2 to 9 MPa (29). It is an inhomogeneous material with porous aggregates; the fine cement mortar covers only the grains of the porous aggregates, without filling the gaps between them after the consolidation (29). A homogeneous consolidation was a quite complex process in the practice.

Therefore, the most of the existing panels have an inconstant distribution of the porous aggregates and cement mortar. This leads to a very complex structural behavior of the construction (29) and inconstant thermal properties (1). In case of the assessed 5-storey 1-464LI series buildings, the lightweight concrete have a design density of 1100 kg/m³, but a possible increase to 1280 kg/m³ was taken into account (28). The assumed compressive strength was 5,0MPa (28). Soviet studies shown, that because of higher mass density and further solidifying process, the strength of lightweight concrete can increase by 60% (25).

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Uneven connection between the wall core and the finish layer

Fig. 21 End of the gable wall panel The dense concrete coverings on exterior and interior faces protect the porous core material from the atmospheric damage like penetrating water and air (30). The panels were casted in wet-on-wet process, which means, that the face layers have very inconstant thicknesses, varying from 21 to 50 mm (exterior face) and from 4 to 15 mm (interior face). Wall panels are casted using a face-down method (28) (exterior face down), so the exterior faces are even. There are few possible exterior finishes (Fig. 22): -

Sand-cement plaster on the protective layer of fine concrete. Used for front walls. Due to the temperature variations micro cracks occur, which are often being constantly rendered.

-

Ceramic coating on the protective layer of fine concrete. Used for gable walls. The coating is often fallen down, exposing the even protective layer. As a result, cracks in the protective layer occur.

-

Washed protective concrete layer, exposing gravel grains. Used for gable walls. The most robust covering, because no flaws can be noted.

Fig. 22 Exterior finishes of the building series 1-464LI (left to right): sand-cement plaster; ceramic coating; washed concrete It is generally recognized, that the exterior layer of fine concrete is not able to protect the porous core from the humidity (29). If the occurring cracks are not sealed on time, they can become 21

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

deeper and reach the porous wall core material, which then can easily absorb considerable amounts of water. The measurements (25) show that the water permeability coefficient of these walls is between 4,13 and 30,31 kg/(m²h0,5), while a construction is considered as a water absorptive, if its water permeability coefficient is more than 2,0 kg/(m²h0,5). Humid walls lead to higher space heating demand (30). Along with the repeating freeze-thaw cycles it may even threat the structural reliability, although 17 year ago (25) (1) it was stated, that it is not the case. Because of the increased density and high humidity, the real U-values of the exterior panels vary from 1,03 to 1,77 W/(m²K) (1), while the standard assumes a value of 1,27 W/m²K for these buildings (21).

These U-values does not meet the current requirements for exterior walls of C-class buildings (0,205 W/m²K) (21).

The exterior wall panel joints are the weakest points of the thermal envelope. They are designed as a closed construction. Two layers of tarred hemp rope act as a water resistant insulating layer.

The gap is sealed with a resin and covered with a fine cement plaster. Bitumen layer on the horizontal and vertical edge of the panels should act as a second water protection layer of the porous lightweight concrete panels. However, the designed lifespan of the sealing resin is only 8 years (30), so their sealing effect is lost long time ago (1). Open gaps are visible in some places (Fig. 20). Because bitumen does not cover the whole open area of panel edges, liquid water can freely penetrate into the wall core. In order to prevent this joints are constantly being covered with various sealing renders, which also do not last long.

Fig. 23 Typical exterior wall panel 2.4.2.3 Interior walls Interior walls are made of 14 cm-thick prefab reinforced concrete panels. Concrete of class C12/15 and between 57 and 101 mm²/m of reinforcement is used (24). They are load-bearing elements.

Surveys show that they are of good condition (1) (25) and should have high load reserves. Only 22

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

partition walls of sanitation units are constructed from lightweight materials. On the both sides of the stairwell, along kitchen and sanitation area, 33 cm-thick wall panels with cavities for ventilation shafts are used. The most obvious flaw of the concrete interior walls is very poor sound insulation between the adjacent condominiums. It happens because of the monolithic structure of the concrete walls: the single interior finish is plaster, no gypsum boards or insulation layer are applied.

The wall sockets are installed at the same position on the both sides of the wall, leaving only a thin separating layer of material. Therefore, they are the weakest points regarding the sound insulation: they conduct the sound so well that they can be almost treated as the eavesdropping devices.

Fig. 24 Exemplar interior wall panel and its reinforcement (24) 2.4.2.4 Floors Floors are made of 10 cm thick prefab concrete slab, which is supported on the whole perimeter.

The slab is reinforced only on the bottom (Fig. 26). Surveys show that they are of good condition (1) (25) and have huge load reserves, especially in the middle section of the building (31). Initially a wooden flooring construction of total 94 mm height is used (28). Its wooden substructure is laid on the sound insulating pads. Therefore, the flooring construction is effectively separated from the load bearing slab, which reduces the spread of the impact noise. However, this initial construction has maintenance problems (because of cavity) and is often individually replaced with a new massive screed-based construction. It is very hard to define the actual portion and structure of the changed floor construction, because of the individual ownership. Therefore it is unclear, whether the sound insulation layer was used and how it was applied on the floor-wall junctions.

Originally, the basement ceiling should be additionally covered with 25 mm insulation layer on the bottom of the slab. Its assumed U-value is 0,71 W/(m²K) (21), while the standard requires 0,258 W/(m²K) for C-class buildings (21). However, this insulation layer is usually absent, therefore only the eventual sound insulation on the top of the slab could prevent heat losses.

23

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 25 Basement ceiling construction: left - initial design (28); right – probable existing situation

Fig. 26 Typical floor slab and its reinforcement (24) 2.4.2.5 Roof The building has a flat roof. Like in the floor construction, a 10 cm thick (28) prefab concrete slab is supported by the exterior and interior walls along the whole perimeter. The roof is insulated with large aerated concrete blocks that lay on the 20 cm–thick L-shaped parapet wall blocks on one side, so forming the required slope. In some cases, openings are made in the parapet walls, supposing that the cavity between the insulation blocks and the roof slab is ventilated. However, such ventilation openings are a fairly rare case and it is generally not clear, whether the cavity is filled with any material. The roof is covered with few layers of bitumen, which are often damaged.

24

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Water may gather in cavities between the layers. Flaws appear especially in connections with parapet walls, ventilation chimneys and around rainwater outlets in the middle of the roof (1).

Because of corroded metal sheeting and damaged bitumen layer, the parapet walls are evaluated as one the most deteriorated elements of the building (25). The measurements (1) show, that Uvalue of the roof ranges between 0,67 and 0,87 W/(m²K), while the standard assumes a value of 0,85 W/m²K (21). It does not meet minimal thermal requirement for C-class buildings (0,165 W/m²K) (21).

Fig. 27 Roof construction 2.4.2.6 Windows Part of the old wood frame windows with double glazing are already individually replaced with conventional plastic frame windows with double glazing (Fig. 8). The actual percentage of replaced windows must be accessed in each particular case. According to the existing investment plans, totally 63-72% of all the windows are changed in the 30-apartments large panel houses in Vilnius.

While in the apartments totally 67-83% of the windows are replaced, the windows in the stairways are changed only in 50% of the assessed buildings, because there a common agreement of the owners is needed. The old wooden windows are leaky and their Uw-value lays between 2,2 and 2,8 W/(m2K) (1), while g-value is assumed to be 0,76 (21). The new windows were installed mostly between the year 1995 and 2005, when a minimal requirement for their Uw-value was 1,9 W/m2K (32), g-value of such windows is about 0,7 (21). They usually have a double glazing with a low-e cover or the air cavity is filled with inert gas (mainly argon). This results in a Ug – value of about 1,60 W/(m²K). Uf – value of typical plastic window frames is about 1,80 W/(m²K) (32). This replacement led to an instant reduction of heating demand mostly because of air tightness of the new windows. It also contributed to indoor comfort, because draughts were reduced (32).

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

However, the installation quality of the new windows varies considerably. Even the new windows can be mounted incorrectly, which causes condensation problems (Appendix 8.2.2.3). In addition to this, the inert gas of the glazing can already be evaporated through the leakages, what downgrades window thermal properties over the time. The portion of the total windows area in the whole façade is 28,4%. For such ratio the current standard requires Uw-value of 1,34 W/m2K for Cclass buildings, so even the windows, which were replaced only 10 years ago, do not fulfill the current requirements.

Table 3 Main properties of the existing windows Window type

Wooden frame, double glazing PVC-frame, double glazing, low-e cover / gases Requirement

Amount

Thermal properties

28-37% 63-72%

Uw 2,2-2,8 1,5-1,9 1,34

Uf 1,7-2,3 1,5-1,8

Ug 2,4-3,2 1,5-1,9

g 0,76 0,63

2.4.2.1 Loggias Loggias‟ floor are made of 3,20 m length, 1,17 m wide, 10 cm thick prefab concrete slabs. They protrude 15 cm from general building exterior surface plane. Slabs are anchored into the exterior walls and additionally supported by 14 cm thick loggias partition walls on the sides. A 5 cm – thick prefab concrete plate is used as a railing. This plate is covered either with ceramic tiles of different colors or with a concrete relief. This is a district-dependent decoration. The loggias are evaluated as one of the most deteriorated building elements (1). The actual condition of loggias elements, especially of the slab, is hardly dependent on loggias glazing and water protection of the slab edges. If the loggia is not glazed or its edges have a direct contact with water or snow, slab may have serious technical defects: through freeze/thaw processes the protective concrete cover can be spalled on the edges, so exposing the steel reinforcement (Fig. 28). Therefore such deteriorated elements may be dangerous for further maintenance and need an urgent repair (25).

Fig. 28 Protruding balcony slab: intact and weathered, with exposed reinforcement.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.2.2

Foundations

Basement exterior walls are made of 300 mm - thick prefab concrete panels. The plinth zone is finished with a rough graveled plaster. The panels are connected similarly to the exterior wall panels. However the underground constructions are more difficult to repair, therefore the occurring damage is much greater than on the exterior walls. There is no sealing resin left in the joints and the water can penetrate freely into the construction (26). All the load-bearing walls are laid on the strip foundations. These are made of the prefab concrete blocks as well.

2.4.2.3 Other Canopy over the entrance is made of 10 cm thick concrete slab and is covered with few layers of bitumen. It is supported by steel columns on one side and by the exterior walls on the other side.

Therefore, it forms a thermal bridge. The bitumen layer is damaged; the slab edges are not sufficiently protected from the water (no metal sheeting). As a result, the canopy is deteriorated and steel reinforcement is exposed in some places. Therefore, its use might be dangerous for the bypassing pedestrians (25).

2.4.3

Building systems

2.4.3.1 Heating

Fig. 29 One-pipe heating system (33): 1 – horizontal distribution pipes (flow), 2 – horizontal distribution pipes (return), 3 – radiators, 4 – standpipe (return), 5 – standpipe (flow), 6 – cross valve.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 30 Heating system: left – modernized technical room (34); right – typical radiators (35) The building is provided with heat from a district heating system. Technical distribution room is located in the basement and might belong either to the district heat provider or to the residents.

80% of these rooms are already modernized (9) (Fig. 30). One-pipe heating system is installed (Fig. 29). Heating medium is hot water of 95/70°C temperature. Iron distribution pipes (total length ~193 m, diameter 15 – 32 mm) are mounted to the basement ceiling and are usually already insulated (heat conductivity ~ 0,33 W/(mK) (36)). Vertical not insulated iron distribution pipes (total length ~336 m, diameter 15 – 25 mm, heat conductivity ~ 1,02 W/(mK) (36)) are freely placed in rooms corners. The iron plate radiators are under the windows (Fig. 30). Because the pipes are left open in the rooms, they conduct airborne noise between different apartments very well. Hydraulic balancing is not provided in the heating system. Temperature is regulated centrally from the technical room; individual regulation of temperature of iron radiators is not possible (33).

According to recent monitoring, average indoor temperature in large panel buildings is +17,6 0C (37), while the Lithuanian hygiene standard HN 42:2009 requires +18-220C during the heating season. Other recent survey (38) shows, that 32,5% of the residents define their flats as too cold in winter, while 6,1% of the residents find the temperatures too high. The reasons of uncomfortable temperatures are not existing individual control of the radiator temperatures and unbalanced heating system. As a result, temperatures can reach up to +22-260C (39) and so boost the energy consumption. In order to rise indoor temperature, some residents install new bigger radiators in their flats, thus additionally misbalancing the whole heating system and dropping the temperature in other apartments. Such practices lead to unfair heating bills, because the whole building has a single heat measuring device in the technical room and the consumed energy is divided according to the floor area of the flats. Considering indoor comfort in summer, 13,7% of people described their flats as too warm (38). According to the measurements (40) (39), the relative air-humidity of the indoor air during the heating season is 23-35%, while the standard allows relative a relative humidity of 35-60% in the residential spaces (41). It means that the air is too dry. On the other hand, the low air humidity prevents mold growth on quite cold interior surfaces. Generally speaking, the thermal comfort in all series of large panel buildings is poor.

28

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.3.2 Domestic hot water

Fig. 31 Domestic hot water (DHW) system (33): 1 – heat exchanger, 2 – horizontal DHW distribution pipes (flow), 3 – horizontal circulation pipes (return), 4 – DHW standpipe (flow), 5 – circulation standpipe (return), 6 – water tap, 7 – towel warmer, 8 – circulation pump, 9 – domestic cold water meter, 10 – non-return valves, 11 – valves.

Fig. 32 DHW circulation system: left – insulated pipes in the basement (34), right – towel heater, formed from the DHW circulation return pipes (35) Domestic hot water (DHW) is heated in the technical distribution room from 11 to 55°C. A constant flow of the hot water is maintained by the circulation system. As shown in the Fig. 31, the domestic hot water runs a fairly long distance until it reaches the user. While the distribution pipes in the basement are usually isolated (total length ~78,4 m, diameter 15-32 mm, heat conductivity ~ 0,33 W/(mK) (36)), the vertical and horizontal hot water distribution pipes inside the thermal envelope have no isolation (total length ~ 378 m, diameter 15-20 mm, heat conductivity ~ 0,67 W/(mK) (36)). As a result, the DHW temperature drops considerably below the initial 55°C, because a big part of energy is wasted through the not isolated distribution system. Additionally, 29

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

the energy losses of the return flow are even intentionally boosted by forming meander-shaped towel heaters directly from the return pipes. These towel heaters are intended to maintain a constant 25°C temperature in the bathrooms. At the end of the return pipe (in the technical room) the return water of about 44°C temperature (33) mixes with the new cold domestic water, so preheating it. This mixture is then additionally heated to the required 55°C by the district heat. The standard monthly heat energy losses of such circulation system are 160-190 kWh per apartment (33). The actual values in the prefab concrete buildings usually reach 300 kWh (42). In case of the analyzed building, the normalized annual energy losses through the DHW distribution system are 68,7 kWh/(m²a). In summer big part of this heat energy is wasted, but during the heating season the circulation heat losses partly become internal gains, artificially reducing the heat output of the heating system (33).

Measurements show, that the daily domestic hot water consumption ranges from about 30 to 46 liter per person, while the average is about 40 liter (43). Its temperature is between 50 0C and 600C (33), as the heat provider only defines the temperature increase of 44 K (42) and the cold water temperatures may differ. For comparison, a Passive house standard assumes 25 liter of 60°C hot water per person daily for multi apartment buildings. This means, that the Lithuanian users simply need more hot water to maintain its comfortable final (mixed) temperature. For the particular investigated building type with 75 persons, the normalized DHW demand ranges between 26,6 and 40,85 kWh/(m²a), while the average value is 35,5 kWh/(m²a).

It is clear, that not only the high energy losses make such DHW system questionable. Because hot water of lower than 55°C temperature is suitable for reproduction of legionella bacteria, the hot water hygiene in this system can be threatened. It is expected, that a constant flow of water and regular temperature increases to 70°C avoid the hygiene problems. However, the DHW distribution pipes have never been changed and do not meet contemporary hygiene standards. Moreover, it is not clear, how often the required temperature increases are performed in praxis. Maintenance of these systems is also complicated (33).

2.4.3.3 Ventilation Building is naturally ventilated. Vertical separate ventilation shafts of bathrooms and kitchens are inside the 33 cm – thick installation panels. In this way each apartment has two its own exhaust air shafts (Fig. 33). They are usually partly stuck, what reduces their functionality. Openings of the ventilation chimneys are not sufficiently protected from the rain, therefore water sometimes get into the shaft and then into the premises (1). Rooms are additionally ventilated through windows.

30

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 33 Natural ventilation system: vertical exhaust air shafts and supply trough windows A survey from the last year (38) shows, that the air quality during the heating season is satisfying only in 54% of apartments in multifamily houses. In almost 20% of them occurs draughts. A recent CO2 monitoring (Appendix 8.2.2.3 (39)) explains this: the average CO2 content in the apartments of multi-family buildings is about 1200 ppm, ranging from 900 ppm on middays to over 2000 ppm mornings. The Lithuanian standard STR 2.09:2005 allows only 1000 ppm (Petterkofer number).

Interesting to mention is, that similar air quality values were measured in various multi-family buildings (soviet large panel buildings, new construction and renovated houses) and a dependence on the year of construction could not be identified. The reason for this is probably the fact, that renovated and newly constructed buildings are provided with the same uncontrolled natural ventilation as the older houses. There are only few renovated houses with a mechanical ventilation system and it is still an exception in a new construction. In addition to this, the air-tightness of older buildings is not much worse than in the new ones, because the old leaky windows are usually changed. In the same study (Appendix 8.2.2.3 (39)) the air-exchange ratios n (h-1) without additional pressure were measured. Because of the natural ventilation, the n-values rise together with the temperature difference between indoors and outdoors. While the temperature difference is 10 0C, the air-exchange ratio is 0,20 h-1, on difference is 25 0C, the n-value reaches to 0,3 h-1. The average n-value is 0,276 h-1. This is clearly below the required air exchange for residential spaces (0,5 h-1). All things considered the air quality in the Lithuanian multi-family houses is insufficient and may cause health problems for the residents on long-term. Additionally it reveals that the large panel buildings are fairly air-tight.

2.4.3.4 Sewage, gas and water Vertical water distribution pipes are installed in a shaft near the WCs. The same shaft is used for DHW and vertical pipes of domestic sewage. Each kitchen has a gas supply. Therefore, gas is mainly used for cooking. Rainwater drainage outlets are installed in the middle of the roof; rainwater sewage pipes are mounted in the stairway and can be accessed on demand. Rainwater

31

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

drainage outlets and pipes can be already corroded. All sewage is directed to the cities canalization system and later treated in wastewater plants.

2.4.3.5 Electricity The electrical installation is designed for about 125 kW power. The common electrical enclosures and its equipment are usually aged and can be even dangerous. High speed optical fiber internet FFTH is provided (up to 600Mbit/s) in the whole city. The final electricity use of the apartments depends on the user behavior and the existing electric devices. However, an average annual electricity consumption in the Lithuanian households is about 890 kWh per person (6). In case of the analyzed particular building with 75 residents, the normalized electricity consumption value is 42,5 kWh/(m²a).

2.4.4

Energy analysis

2.4.4.1 Energy balance

Useful energy:

Final energy: Qf – total final heat energy demand Qh,f – final space heating energy Qh – space heating energy demand demand Qdhw – domestic hot water demand Qh,f,r –final space heating energy Qi – internal gains demand, as measured in the reality Qs – solar gains Qc,i*μ – useful internal energy losses through Qdhw,f – final energy demand for DHW circulation (during the heating season) DHW Qdhw,f,r – final energy demand for DHW, as measured in the reality Qv – ventilation losses

Qt – transmission losses Qc,i*(1-μ) – not useful internal energy losses through DHW circulation μ –utilization factor for internal gains

Primary energy: Qp –primary energy demand fp,d – primary energy factor for district heat

Qc – total losses through DHW circulation Qc,e – external losses through DHW circulation Qg – generation losses Qh,d – heating distribution losses

Fig. 34 Energy balance for the DHW and heating system, based on ISO 13790 (see Appendix 8.4) 32

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.4.4.2 Real energy consumption 70% 60% Buildings

50% 40% 30% 20% 10% 0%

kWh/(m²a)

Fig. 35 Real space heating energy consumption map of the city of Vilnius (left) and distribution of the real heating energy consumption values of the analyzed type 1-464LI-18/2 (right) (12) The data of the real space heating energy consumption for all buildings in Vilnius, which are connected to the district heating system, is provided by the district heating provider and is online accessible (12). The buildings are sorted into 15 real energy consumption classes (FEVK) (44).

The FEVK is defined by recalculating the energy consumption values to the degree-days. In this way, the influence of the different heating seasons is removed and a comparison enabled (44).

However, in order to have a better understanding of the energy consumption, the energy consumption values for the various FEVK were recalculated for the test reference year (see Table 4). The energy consumption map and the respective values for the analyzed building type are shown in the Fig. 35. The distribution represents mainly the different technical condition of the buildings, because due to the absence of individual indoor temperature control, the influence of the user behavior covers only the ventilation habits. The average heating energy consumption ranges between 100 and 120 kWh/(m²a). This is a fairly low value, especially considering the fact the DHW circulation losses are about 68,7 kWh/(m²a). Therefore the methodology of the real energy demand calculation must be considered. Thereby, the energy balance chart (Fig. 34) is useful. As a single heat accounting device in the technical distribution room measures the energy consumption, it is impossible to accurately define, how much of the heat was used for circulation and how much – for the heating. In order to extract the real heating energy consumption value, the measured average consumed heat value from May and September (off-heating season) is regarded as an average energy consumption for circulation and excluded from the total heat demand within heating season (44). As a part of the energy losses of the circulation system surely cover the space heating demand (low μ-value), the resulting real heating energy consumption value Qh,f,r is lower than the Qh,f, which is estimated according to the standard methodology of ISO 13790. The actual portion of useful losses through circulation Qc,i*μ cannot be defined. Therefore, in order to correctly represent the total heat consumption of a particular house, the provided 33

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

heating consumption values must be shown together with circulation system losses. The final average energy consumption values for heating, DHW and its circulation and miscellaneous household equipment are shown in the Fig. 36.

Final energy consumption

kWh/(m²a)

250 200

35

150

69

Miscellaneous DHW

100

Circulation

110

Heating

50 42 00 Heat

Electricity

Fig. 36 Real average final energy consumption values 2.4.4.3 PHPP calculations Detailed energy calculations were conducted in order to identify the most influential factors on the energy demand and specify the reference energy demand value for the further calculations of the energy and costs savings due to the retrofit. Because the methodology of the current Lithuanian energy standard STR 2.01.09:2012 is inaccurate (see chapter 2.6.3), a calculation tool of Passive House Institute was used – Passive House Planning Package (PHPP) (version 8.6). This Excelbased tool is used to certify buildings to the Passive House standard. It is implemented internationally and is also used in Lithuania. The energy monitoring of the existing buildings, which were planned with the PHPP, shows a clear correlation between the real energy consumption and the calculated values. Such a high accuracy is needed in order to reliably predict the energy savings and the economic effect of the energy retrofit.

2.4.4.3.1 Climate The PHPP database includes a climate dataset for Vilnius. The main climatic parameters of both Lithuanian energy standard STR 2.01.09:2012 and PHPP are summarized in the Table 4 and shown in the Fig. 37. The differences are negligible, so the proposed PHPP climate dataset is reliable and can be used for the energy calculations.

34

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Table 4 Comparison of the main climatic parameters of the Lithuanian standard STR 2.01.09:2012 and PHPP climate dataset for Vilnius

Lithuanian standard STR 2.01.09:2012 PHPP database

Heating period duration, days 224

Degree-hours (18°C interior temperature) Kh/a 96120

Total global sun radiation, Wh/(m²a) 994

225

93646

944

20

180 160

Temperature, °C

15

140

10

120 100

5

80

0

60 40

-5

20

-10

Global sun radiation, kWh/m²

Data source

PH Vilnius STR Vilnius PH global sun radiation STR global sun radiation

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Fig. 37 Monthly values of the exterior air temperatures and total global sun radiation 2.4.4.3.2 Input For an accurate input of the building geometry and shading objects, a 3D model was built in Google SketchUp 8, using a plug-in of Passive House Institute – designPH (Fig. 38). It enables assigning of thermal properties for the geometry elements, performs rough year-based calculations and exports the data to the PHPP for more detailed analysis.

The main input parameters are shown in the Table 5. It must be distinguished between the treated floor area (TFA) and the apartment floor area (AFA). The first used is in the PHPP in order to estimate correct absolute energy demand values and to identify the threshold value of the Passive House - space heating energy demand. The AFA is used to represent all the other values: final energy, primary energy, CO2 emissions and costs. The absolute values in both cases remain the same. The use of AFA is reasonable, because it is relevant for the end-user – real energy accounting is based on this area (33), so proportionally distributing the heat demand (and energy costs) of the commonly used stairways. Moreover, the same reference area is used in the current investment plans.

35

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 38 The analyzed building with environment in designPH Table 5 Main input parameters for energy calculations with PHPP General properties Treated floor area (TFA), m² Apartment floor area (AFA), m² Occupants Total air exchange rate n, 1/h PHPP climate dataset

1620,2 1571,9 75 0,26 Central Europe – [LT] Vilnius

Volume, m³ DHW temperature, °C DHW l/(Pers.*day) Ventilation volume, m³ Indoor air temperature, °C

6036 60 25 4324 18

Building elements

Exterior walls facing the exterior air Exterior walls facing the glazed loggias (100% of the loggias glazed) Roof Basement walls Basement ceiling Windows

Area, m²

U-values, W/(m²K)

670,55 244,80

1,27 + 0,10 for thermal bridges 1,27 + 0,10 for thermal bridges

Temperature factor Tf, 1,00 0,70

402,19 34,34 402,19 237,09

0,85 + 0,10 for thermal bridges 2,66 0,89 + 0,10 for thermal bridges new (70%) – 1,90; old (30%) – 2,50

1,00 0,45 0,45 Depending on the wall

2.4.4.3.3 Results of the energy analysis Useful energy balance of the existing building is shown in the Fig. 41. Thereby the TFA is taken as a reference. The transmission losses constitute about 80% of the total final heat energy losses, whereby windows and exterior walls have the biggest share of about 100 kWh/(m²a). In contrast, the ventilation losses are relative small. This is because of a very low air exchange rate in the existing buildings.

36

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Windo ws; 43,7

Doors; 1,1

Exterio r walls loggias ; 12,4

Roof; 22,1

Exterio r walls; 54,7

Basem ent walls; 2,5

Basem ent ceiling; 10,3

Fig. 39 Useful heating energy balance of the existing building (right) and the transmission losses (left) 35 30

kWh/m²

25 20 15 10 05 00 Jan

Feb

Mar

Apr

May

Space heating energy demand

Jun

Jul

Aug

Total gains

Sep

Oct

Nov

Dec

Total losses

Fig. 40 Monthly useful heating energy balances of the existing building

Fig. 41 Final energy balance for DHW and heating systems of the existing building 37

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

The final energy balance of the DHW and heating system is shown in the Fig. 41. As mentioned before, the AFA is taken as a reference area. It is seen that the distribution and generation losses of the heating and DHW system together constitute about 20% of the whole final heat energy demand of the building. Considering the DHW circulation, the initial assumption about the partial utilization of its energy losses is confirmed. Only a half of total circulation losses are not usable – occurs out of heating period or out of thermal envelope (in the basement). The rest circulation energy covers 16,7% of the space heating demand. If the DHW system were not fundamentally retrofitted, it damps the positive effect of the other energy efficiency measures, not to mention, that the gains of circulation system are totally uncontrolled.

2.4.4.3.4 Comparison In order to compare the calculated final energy demand with the real one, the following modifications must be made (see Fig. 34): -

The useful energy demand DHW (Qdhw = 26,7 kWh/(m²a)) is treated separately from the DHW circulation losses Qc.

-

The part of the DHW circulation losses, which is utilized as useful heat gains (Qc,i*μ = 23,0 kWh/(m²a)), is excluded from the final heat energy demand value Qh,f and added to the DHW circulation losses Qc.

-

The real space heating energy consumption is recalculated for PHPP standard, basing on the degree-hours (from 96120 Kh/a to 93646 Kh/a).

Final energy demand comparison

70%

250

150

50% 27

35

45

69

139 100

DHW DHW circulation

107

50

Heating

Buildings

EUR/(m²a)

200

60% PHPP Reference building

40% 30% 20% 10% 0% 40-60

0 PHPP

Real values

60-80 80-100 100-120 120-140 140-160 160-180

real energy consumption for space heating, kWh/(m²a)

Fig. 42 Final energy consumption for DHW, circulation and heating: comparison between the PHPP calculations and the real average value (left) The comparison of the PHPP calculation results and actual values is shown in the Fig. 42. The final total energy demand, considering the heat for the space heating, DHW and its circulation is almost equal to the real average values. On one hand, the energy demand for the circulation is more than 20 kWh/(m²a) lower than the real values and the DHW demand is by about 10 38

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

kWh/(m²a). On the other hand, the final estimated space heating demand, as it is defined in the measurements of the real values, is about 30% higher. The differences of the space heating demand can be caused by three factors: -

More useful circulation energy losses due to the worse circulation system in general

-

The assumed worst case scenario for the shading conditions leads to lower solar gains and higher space heating energy demand

-

The indoor air temperature can be lower than the assumed 18° C.

The higher circulation energy losses may be of the following reasons: -

Possible deviations regarding the heat conductivity of the pipes and their total length

-

Generation losses of the DHW system higher than expected

The differences in DHW demand can be regarded as irrelevant, because this figure is completely dependent on the user behavior. All things considered, the energy analysis results seem plausible and the minor deviations from the real values are acceptable. Therefore, the PHPP methodology is suitable for the further energy calculations and enables an accurate energy saving and economic forecast.

PE-demand

Operation costs 300

8 6

4

250 11,82

kWh/(m²a)

EUR/(m²a)

12

200 150 100

70 60

274 kgCO2/(m²a)

14

10

CO2 emissions

50

61,1

40 30 20

2

50

10

0

0

0

Fig. 43 Reference values: annual operation costs; primary energy demand; CO2 emissions 2.4.5

Financial consequences due to the heating bills for the residents

In order to find out, what part of their incomes the residents should pay for energy, four different household structures for the same 2-room flat (47,23m² floor area) are created. First household type is a pair of working adults, the second one – one working adult and a child, the third type consists of two pensioners and the last one – of a pensioner and a child. It is assumed, that the annual incomes of each adult equals an average net salary in Vilnius, which was is 7367 EUR per year in Vilnius (6). An average annual pension in 2015 was 2963 EUR (45). The future salary development scenario is based on middle-term forecasts of the Lithuanian National Bank, whereby a 4,8% increase till the year 2016 is predicted (46). In order to have a reserve, an annual salary 39

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

increase of 4% is assumed till the year 2020. Afterwards a very conservative annual increase of 2% is assumed. In this way a low economic growth scenario is assumed. The pension size is directly linked to the average salary and develops respectively. A so called 10% definition is used to define fuel poverty, whereby a household is said to be in fuel poverty if it needs to spend more than 10% of its income on fuel to maintain an adequate level of warmth (18-210C temperatures indoors) (47). The estimated final heating energy demand value of 161,9 kWh/m² is assumed for the every year. District heat price scenarios of 3% and 4% annual energy price increase are used.

According to the statistics of the previous years, only the households with two working persons were not under the fuel poverty limit in the period of radically increased district heating prices.

Today energy prices are reduced and incomes of the residents rise quite fast, thus avoiding the energy poverty for few decades. However the reserves for the single working person and the pensioner couple might be insufficient, as the eventual peaks of the energy prices can coincide with the colder winters, thus boosting total heating bills and constituting a serious financial burden.

It must be noted, that even after the recent district heat price reduction, the household of a single pensioner remains in the fuel poverty, which only deepens over the year. As the pensioners are representing about 25% of the population in the large panel districts of series 1-464LI, it can be stated that the fuel poverty is a crucial issue. In order to avoid it, the state partly reimburses the heating costs for about 7% of all the residents provided with the district heat (48). Of course, the more rational way is to invest this money into the energy retrofits.

4000 3500 3000

EUR/a

2500 2000 1500 1000 500 0 2010

2015

2020

2025

2030

2035

2040

2045

Fuel poverty limit - 1 pensioner

Fuel poverty limit - 2 pensioners

Fuel poverty limit - 1 working

Fuel poverty limit - 2 working

Energy costs - 3% annual increase

Energy costs - statistics

2050

Energy costs - 4% annual increase

Fig. 44 Risk of fuel poverty for various households structure (typical 2-room apartment (47,23 m²) in the large concrete panel building type 1-464LI-18/2) 40

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.5 2.5.1

Legal requirements Energy

A++ A+ A B 0

10

20

30

40

50

60

70

80

Space heating energy demand, kWh/m²a

Fig. 45 Maximal space heating energy demands Qh of various building classes for residential buildings of 1700 m² floor area (21) According to the Lithuanian energy standard STR 2.01.09:2012, buildings are sorted to 9 energy efficiency classes (G to A++). Since January, 2016 new buildings must achieve class A, retrofitted buildings – class C (Fig. 45). The requirements of the Lithuanian energy standards are compared with the other ones in the Table 6. Thereby it is also shown, that the thermal properties of the assessed large concrete panel building of type 1-464Li-18/2 do not comply with the current Lithuanian requirements for C-class buildings (marked in red).

Table 6 Thermal properties of the assessed building of type 1-464LI-18/2 and the respective requirements of various energy standards Energy standard

U-values, W/(m²K)

Thermal bridges

Airtightne ss -1

kWh/ (m²a)

0,276 (0,80)

2

137 (170)

0,19

1,50

-

1,00

0 - 0,05

0,60

22,55

0,85

0,01 or more

0,601,00

25,00

Roof

Against unheated spaces

Exterior walls

Doors

Wind ows

W/(mK)

n50, h

Existing 1-464LI1 18/2

0,670,87 (0,85)

0,94 (0,71)

1,031,77 (1,27)

1,5-2,8

1,52,8

-

Lithuanian building class C - for retrofit (21)

0,16

0,26

0,21

1,34

1,34

Lithuanian building 0,10 0,14 0,12 1,00 class A - new construction (21) Energy retrofit with 0,12 0,21 0,15 0,80 Passive House components EnerPHit (49) 1 Values in brackets according to the STR 2.01.09:2012 2 under normal pressure in the premises (not 50 Pa difference)

Space heating energy demand

41

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.5.2

Fire safety

The Lithuanian fire safety regulation (50) distinguishes between 3 fire resistance levels of buildings, whereby the first level has the strictest requirements. Multistory residential buildings belong to this level. The actual fire safety requirements for building elements are depending on the fire load category, which must be calculated separately. The first category has fire load of more than 1200 MJ/m², while the third class less than 600 MJ/m². The large panel multi apartment buildings usually belong to the 2nd fire load category (600-1200 MJ/m²). The relevant fire resistance requirements are summarized in the Table 7. Generally, building products of B-s1,d0 combustibility class must be used for the exterior finishes (cladding, render etc.). However, 30% of each façade area of residential buildings with less than 26,5 m uppermost floor height (up to 9-storey) can be covered with C–s2, d1 materials. Alternatively, 15% of each facade area can be finished with D– s2, d2 materials. For the load bearing elements of the buildings, which belong to the 2nd fire load category, only materials of not less than A2–s3, d2 combustibility class can be used. To sum up, a wall insulation system, composed of combustible insulation materials (for instance wood wool, cellulose) and fire resistant exterior covering (B-s1,d0 combustibility class) can be used for all large panel buildings. A wooden framework is allowed as long as it is only a self-bearing construction. If it takes some loads from the main structure, not combustible structural materials must be chosen.

Table 7 Fire resistance requirements for building elements of the buildings of the 1st fire resistance level (50)

(1)

REI 180

R 120

(1)

EI 30

Stair runs and landings

EI 30 (1) REI 90 RE 30 (o↔i) EI 15 (1) (1) (1) I 2 REI 120 R 90 EI 15 REI 60 RE 20 (o↔i) EI 15 (1) (2) (1) 3 REI 90 R 60 EI 15 REI 45 RE 20 (o↔i) (1) Only materials of not less than A2–s3, d2 combustibility class can be used.

(2) Only materials of not less than B–s3, d2 combustibility class can be used 1

Interior walls

Roofs

Floors

Exterior walls

Load-bearing constructions

Not load-bearing interior walls

Stairwells

Walls and floors between fire compartments

Fire load category

Fire resistance level of building

Fire resistance of building or fire compartment elements (min)

REI 120

R 60

REI 90

R 60

REI 60

R 45

42

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.6

Current retrofit practices in Lithuania

2.6.1

Energy retrofit program

In order to reduce the energy consumption of the residential building stock, state has adopted a Program for the Refurbishment of Multi-Apartment Buildings. Its target group is the multi-apartment buildings, which had been constructed until the year 1993. The key-objectives of the program for the year 2021 are to reduce the total estimated heat energy demand of these buildings by at least 20% (1000 GWh) and to decrease their total annual CO2 emissions by at least 230 000 t, in reference to the year 2005 (9). In order to achieve this goal at least 4000 state funded energy retrofit projects of old multi-family buildings should be completed (9). A lot of different systems of state support were already tested. However, none of them was able to initiate a real Retrofit boom: between 2005 and 2012 only 479 (51) from over affected 35.000 buildings (9) were retrofitted. In 2013 a new system was implemented, which appears to be the most successful. Since 2013 581 buildings has been modernized, further 1699 are in the process; over 3600 more have already arranged required investment plans (51). It is seen that the goals of the Program are going to be attained. Two ways to start the retrofit process are possible (51): -

Initiative of apartment owners‟ associations or the building administrating company. The responsible person is an elected president of the association. Special public institution Housing Energy Efficiency Agency (BETA) helps them on administrative issues of retrofitting. This scheme is valid since 2005. However, the administration of all construction works is a complex task, which requires specific knowledge and time and cannot be easily manageable for everyone.

-

Initiative of municipalities. The municipalities make lists of the most energy inefficient buildings in their administrative area or the residents propose their own buildings for the Retrofit. A special municipal administration company is then responsible for making the retrofit project, evaluation of its economic consequences (investment plan) and financing.

The residents need only to accept the project and investment plan, which reveals, how much they must pay for the retrofit and what benefit they can expect. The municipal administrator takes the responsibility for the further administrative and construction issues.

Evaluating the residents‟ satisfaction on the current retrofit program, 81% of residents declared, that repayment of credit had no or very little influence on personal finances, 95% would recommend for other residents associations to refurbish their houses (37). The gained experience allows the residents to maintain their common property more cooperative later.

Since the 1st October 2015 the government reimburses (51): -

15% of investments for energy efficiency measures, if the calculated heating demand is reduced by 20%.

-

Additional 15% of investments for energy efficiency measures, if the calculated heating demand is reduced by 40% (resources from the Climate Change Special Programme) 43

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

-

50% of design costs (but not more than 5-8% of total investment)

-

50% of technical supervision costs (but not more than 2% of total investment)

-

50% of project administration costs (usually for the discussed municipal administration company)

-

100% of total investment for receivers of a tangible state support

-

State-guaranteed credit with fixed annual interest rate of 3%

As a result, the government reimburses more than 30% of the total investment. The following construction works are supported (51): -

Refurbishment or replacement of the heating and domestic hot water systems

-

Refurbishment, replacement or installation of ventilation systems (including mechanical ventilation with heat recovery)

-

Refurbishment of other building systems (sewage, electricity, fire-safety devices, domestic water systems, drainage)

-

Roof insulation, mounting of new roofing, installation of a new sloped roof (if no new living rooms in the attic are planned) with an insulation of the uppermost floor slab. Installation of the stairs, if they are required to access the building systems on the roof.

-

Exterior wall insulation, including the removal of the technical defects

-

Glazing of balconies and loggias according to common design, including the repair of the deteriorated elements

-

Window replacement to more energy efficient ones

-

Insulation of the basement ceiling

-

Making the entrances to the stairways and elevations barrier-free

All things considered, the current retrofit program provides big financial resources for the energy retrofit. However, the program lacks of an integral view, as the eventual space extensions or implementation of the barrier-free accessibility are not supported. As a result, the functional quality of the buildings are not improved and the large public investments may be wasted for buildings and neighborhoods, where still no one wants to live.

2.6.2

Typical retrofit projects

Because most of the residential building stock, which can be retrofitted with the state support, are constructed according to the standardized projects (prefab concrete as well as masonry), typical 44

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

retrofit projects are proposed. They are officially approved by the state and should guarantee the design quality and compatibility of the key retrofit solutions with the existing legal requirements (thermal properties, fire-safety). Moreover, it reduces final design costs. Therefore, the maximum state support for design works is limited to the 2% of the total investment. Construction and building systems drawings, quantities take-offs, technical specifications for materials and construction works are included. A typical retrofit project covers all possible energy efficiency measures (insulation of the thermal envelope, replacement of heating system, ventilation, etc.).

During the real Retrofit it is adapted according to the financial capabilities of the residents and actual condition of a particular building. Over 50 typical retrofit projects are available today (51).

2.6.3

Investment plan

Investment plan is an economic feasibility study of the retrofit project. It aims to reason the profitability of the proposed energy efficiency measures on the basis of technical condition survey, energy certificate and actual energy consumption data. Thereby a total investment size and its distribution on particular households are defined. In addition to this, an action plan for further Retrofit works is set. The investment plan is arranged by the project administrator according to the technical task of the client and current requirements of the Refurbishment Program. The plan consists of the following parts (52): -

Situation description

-

Main technical information about the building (size, construction type, quantity take offs)

-

Evaluation of the existing technical and energetic condition (visual survey and energy certificate, real energy consumption data)

-

Planned energy efficiency measures and their parameters

-

Evaluation of energy efficiency of the planned measures

-

Preliminary costs of the planned measures

-

Profitability of the planned measures: payback periods and credit repayments

-

Action plan for further Retrofit project implementation and financing

The investment plan must be discussed with the residents and attain their approval.

Although the regulation of the investment plans is constantly improved, the prepared plans still have some serious flaws. In order to show these, an average project of the same building type as in the chapter 2.4 is evaluated in detail (Sausio 13-osios street 7 (4A5b), Vilnius) (34). It was arranged and approved in 2014. Thereby the building class C is achieved. The energy efficiency measures are limited to the insulation of the thermal envelope (except for basement ceiling). For the exterior walls a polystyrene composite heat insulation system is proposed. The heating and DHW circulation pipes are not replaced or insulated. The total refurbishment price is 129 EUR/m², 45

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

additionally 46% state support can be availed, total credit size (20 years, 3% annual interest rate) is 93,5 EUR/m².

The most important problem is the applied inaccurate calculation methodology of the Lithuanian energy standard STR 2.01.09:2012. False estimation of the energy demand and savings leads to false predictions of the economic effect, thus misleading the owners. Although it is briefly mentioned, that the calculated energy savings may differ from the real ones by 25%, this note is not reflected in the further calculations. The declared energy balances before and after the retrofit are shown in the Fig. 46. The sum of the space heating energy demand and the DHW demand of the existing conditions is used as a reference for calculation of energy savings. The key-error in the calculation methodology is too high values of the uncontrolled air-infiltration, which boosts ventilation losses. As the retrofit allows a decent level of the air-tightness, the estimated ventilation losses are reduced almost by a half. Therefore, the resulting energy savings of 110 kWh/m² considerably exceeds the real savings. As consequence, a remarkable payback period of 7,7 years is achieved. In addition to this, the economic effect estimation is made using another method.

Thereby the normalized real final heating energy consumption value (130 kWh/m²) are taken as a reference. The space heating energy demand of the retrofitted building is calculated by using the energy savings ratio (55%) of the previous calculations. In this way two completely different energy demand values are mixed and compared – final and useful energy. The real heat consumption value does not include the DHW demand, but includes distribution and generation losses of the heating system, which are not considered in the estimated values. Although the output of this method may be more plausible, it still cannot provide the correct results.

Both methods do not consider different heating demand in different apartments, which depends on the exterior envelope area. As the currently the energy prices are uniformly distributed for the whole building, the implantation of the individual accounting leads to different energy savings through retrofit. Therefore the average values of the economic benefit do not represent the real effect for separate apartments, which can be very poor for the corner flats. To sum up, the applied methodology in the investment plans leads to the misleading evaluation of the economic retrofit effect. Such unfair practices may discredit the whole idea of the state-supported energy retrofits.

46

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Fig. 46 Energy balances in the approved investment plan of a large panel building of type 1-464LI18/2 (34): existing conditions (left) and retrofit (right)

Calculation based

Real consumption based

20

20 19,03

4,15 15 6,48

10

savings credit

8,41

5 0

energy costs

EUR/(m²a)

EUR/(m²a)

15

0,72 10

12,89

6,48

savings credit energy costs

5

5,69

0 existing

retrofit

existing

retrofit

Fig. 47 Calculated energy costs, credit repayment and costs savings in the approved investment plan of a large panel building of type 1-464LI-18/2 (34): left - using the calculated values, right – using the real consumption value as a reference

47

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.6.4

Energy retrofit of large panel building series 1-464LI in Vilnius

According to the Vilnius energy consumption map (12), there are currently 9 modernized 5-storey buildings of series 1-464LI in Vilnius. Their average final space heating energy consumption is about 50 kWh/(m²a). The most efficient house (Tuskulėnų street 28, Fig. 48) consumes only about 36 kWh/(m²a), the worst one (Architektų street 25) - 63,3 kWh/(m²a). Considering the fact, that the initial average energy consumption for the space heating of these building types is about 110 kWh/(m²a), and the circulation system is not refurbished, the energy savings after the retrofit range between 75 and 47 kWh/(m²a). It must be additionally mentioned, that after the retrofit the residents get more individual temperature control and the average indoor temperature rises from 18 to 20°C. In all discussed objects the retrofit was completed before the year 2014, when the stricter requirements for the thermal envelope of modernized buildings were still not in force (21).

Usually the following works were executed (51): -

Wall insulation (min U-value 0,35 W/(m²K) (21))

-

Roof repair and insulation (min U-value 0,24 W/(m²K) (21))

-

Replacement of old windows (min Uw-value 1,82 W/(m²K) (21)) and loggias glazing

-

Hydraulic balancing of the heating system, installation of thermostatic valves

Fig. 48 Building of type 1-464LI-18/1 after the retrofit (Tuskulėnų Street 28) and its actual energy consumption for the space heating in three last heating seasons (12) The optimistic economic effect calculations were performed for the most successful energy retrofit (Fig. 48, final heating energy consumption 35 kWh/(m²a)). Thereby two cases regarding the energy prices and state support were assessed – situations in the year 2014 and 2016. The investment costs are taken from the previous chapter. The relevant data is listed in the Table 8. It is seen that the payback period difference is about 40%. Moreover, assuming that the whole investment is covered by a 20 years-long credit with the annual interest rate of 3%, the retrofit gives a negative economic effect on the defined conditions in 2016. These calculations reveal that the actually achievable energy savings are still insufficient in order to attain solid total costs savings, including 48

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

the credit repayments. The currently falling energy prices and gradually decreasing state funding additionally worsens the economic perspective. Moreover, it is proven that a more accurate energy calculation methodology must be applied in order to accurately define, whether the retrofit measures result in actual cost savings, as these savings tend to be fairly low. Therefore, the energy retrofit should provide significant functional benefits, which would additionally increase the real estate value of the condominiums, compensating the low energy costs savings.

Table 8 Economic forecast for the retrofitted building of type 1-464LI-18/1 (Tuskulėnų Street 28)

Space heating energy consumption, kWh/(m²a)

Existing

Retrofit 2014

Retrofit 2016

110

35

35

Heat price, EUR/kWh (53)

0,0765

0,0558

Investment, EUR/m²

125

125

Financial state support

46%

35%

Investment for residents (credit 20 years, 3% annual interest) EUR/m² Payback period, years (3% annual energy price increase)

125,7

151,4

10,5

15,9

Situation year 2016

20

20

15

15

10

0,98 10,94

6,48

5

savings credit energy costs

3,48

0 -5

EUR/(m²a)

EUR/(m²a)

Situation year 2014

10 7,79 5

savings credit

7,98

energy costs 2,54 -2,35

0 -5

existing

retrofit

existing

retrofit

Fig. 49 Annual expenses before and after the retrofit, regarding different energy prices and state support in the year 2014 and 2016

49

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.6.5

Urban revitalization projects

A necessity to refurbish the whole residential districts, not solely the separate buildings is acknowledged by the state. Despite that, today still none of such projects have been realized and only few are in plans. A pilot revitalization project for a soviet district Ţimūnai in Vilnius within the framework of the European project Re-Block (architecture office PUPA and Vilnius municipality) could be treated as exemplary, because it effectively involves the residents and other stakeholders into the process of the development vision creation. The proposed approach could be implemented in other similar soviet districts. Firstly, a detailed socio-demographic and urban research, including residents‟ survey and debates, was performed in order to identify the problems and challenges. It was later used as a base for the preparation of the development vision. Thereby workshops were organized in order to define the new structure of the neighborhood and create solutions for the public space improvements, courtyards, paths, cycling routes, infrastructure and car parking. The plan of this development vision is shown in the Fig. 50. Few neighborhoods in the territory are selected for the testing of various innovative building retrofits methods like energy retrofit in passive house standard or in-depth transformation with partial deconstruction (14). On the final stage the local action plan was formed, where financial and administrative issues are outlined. The design phase should be finished in 2016.

Fig. 50 Revitalization plan of the soviet district Ţirmūnai in Vilnius (arch. PUPA, Vilnius city municipality) (14) 50

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.7 2.7.1

Retrofit examples abroad Modifications of large panel buildings in Leinefelde, Germany

Fig. 51 Modification of a large panel building in the city of Leinefelde (Germany), Stefan Forster Architects (54) Urban development in the territory of the former DDR is quite similar to the situation in Lithuania.

Huge large panel buildings districts were the only type of a residential housing. After the German reunification, the smaller cities began to shrink, because their industry was not competitive and the residents moved to the other places searching for job, leaving empty buildings behind. A city of Leinefelde (150000 residents) is an example of such development. However, the population shrinkage there was perceived as a chance for a more sustainable future. Already in 1994 the municipality has decided to execute a massive Retrofit program. The abandoned buildings were demolished. However, researches revealed that the large panel buildings are exceptionally suitable for large-scale modifications. An open architecture contest was organized. The winner Stefan Forster proposed to modify the existing buildings with simple architectonic modification techniques of subtraction and addition (54). The previously monotonic districts of 5 to 6-storey blocks were transformed to the diverse human-scaled neighborhoods of smaller buildings and various open spaces with a clear identity. Private ground floor gardens were designed, 1,80 m deep balconies added and windows enlarged. The interior spaces were also fully re-planned. The thermal envelope was improved according to the minimal legal requirements (additional 10 cm exterior wall insulation). As a result, the estimated final energy demand was decreased by a half. Such large scale modifications with partial demolitions were performed in a not occupied condition. In contrast to Lithuania, the apartments there were not automatically privatized: they belonged to a public housing company, which was the main organizer of the construction works. Although the tenants were forced to leave their apartments during the construction, they were able to make their own proposals for the floor plans. Therefore, a harmonic full-scale re-development was possible. Today all the apartments in the retrofitted large panel buildings are occupied and the city has even become a target of an architectural tourism. This re-development received German and European Urban Planning Awards in 2003 and 2004.

51

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.7.2

Transformation of a housing block in Paris, France

Fig. 52 Interior space before and after the transformation in a 16-storey housing block in Paris (France), Lacaton & Vassal (55)

Fig. 53 Transformation scheme – addition of a new living space and a balcony, Lacaton & Vassal (56) Architecture office of Lacaton & Vassal has already executed many transformation projects of large-scale housing blocks in France (56). Thereby the main goal usually is a fundamental improvement of a life quality in the existing buildings, so avoiding their demolition and related social problems. A typical solution is shown in the Fig. 52 and Fig. 53. Existing facades with small windows of a concrete skeleton-frame structure are removed. Then, new self-supporting structures are added on the periphery of the existing building at every floor. They form generous winter gardens with balconies, which are filled with daylight and act as living room extension. The added structure is prefabricated, so that the residents could stay in their apartments during the construction works. The occupants can enjoy exceptional views through large transparent surfaces. Although the energy efficiency in the maintenance phase is rather of a secondary importance in these projects, a significant amount of primary energy and resources is still being saved by avoiding demolition and new construction.

52

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.7.3

Energy retrofit with prefabricated timber elements in Augsburg, Germany

Fig. 54 Energy retrofit with prefabricated timber elements in Grüntenerstr, Augsburg (Germany), lattkearchitekten (57) A typical multi-storey residential building from postwar period in southern Germany was selected as a demonstration project in European project E2Rebuild (57). E2Rebuild promotes innovative industrialized processes in the retrofitting sector in order to reach a sustainable, energy and cost effective result. The Retrofit of the building in Augsburg was ordered by a public housing company and designed by a Frank Lattke architecture office. The retrofit covered the thermal envelope, space extensions, building systems and bathrooms. The envelope was modernized using a façade retrofitting system of prefabricated timber elements. It bases on TES EnergyFacade system. Highly insulated panels (U-value = 0,13 W/(m²K)) with modern windows were used. The existing loggias were transformed into winter gardens, so eliminating thermal bridges and gaining more floor area.

Moreover, new loggias were constructed, so providing an additional outdoor space. As a result, the estimated space heating energy demand was reduced from 220 kWh/(m²a) to 30 kWh/(m²a) and an additional value of the apartments was gained. The prefabricated retrofitting system allowed the residents to stay in their apartments during the whole construction works. The project was repeatedly awarded in various national German contests in the year 2012-2013.

Fig. 55 Workflow in the TES-process (58)

53

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.7.4

ELEMENTAL social housing project in Iniqueqe, Chille

Fig. 56 ELEMENTAL social housing project in Iniqueqe, Chile: state funded concrete part of the building and individual extensions in between (55) A company ELEMENTAL is founded by a Chilean architect Alejandro Aravena. It focuses on various infrastructure and housing projects, which can effectively upgrade the life quality of the poor. In their works ELEMENTAL seeks to create basic technical conditions that can guarantee an effective value gain over the time. A social housing project in Iniqueqe, back in 2001, is a great example of this philosophy. The aim of the project was to re-accommodate 93 families on the site of illegal houses (favelas). The provided budget was only US$7500 pro family. ELEMENTAL converted this budget into a social investment rather than an expense. The money was used to provide the basic infrastructure in the neighborhood and construct fundaments and a load-bearing structure of the small houses of 36 m². However, there was enough space left for a further extension and the residents were informed how to do it on their own. As a result, people were able to double the square meters of their initial homes for only US$1.000. 5 years later, any house in the Elemental Iquique project is now valued at over US$20.000. ELEMENTAL promotes this design approach as a way to manage a rapid urbanization, when more than a third of urban population will live under the poverty line (55). As the speed and scale is needed, the prefabrication of the elements is suggested. Generally, this situation strongly resembles high housing demand in postwar period in Lithuania (or Europe). However, a provision of a robust framework and then allowing „building on your own‟ could be very promising solution. The predefined individuality damps the negative effects of mass construction like monotonic image or lack of individual control. In addition to this, the individual effort on the home extension is followed by a strong felling of responsibility for this property. In technical point of view, this means a better maintenance of the existing structure. Both aspects would be very welcome in the Lithuanian large panel building context.

54

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.8 2.8.1

Lithuanian construction sector Prefab timber construction

In Lithuania, the construction sector generates about 6-10% of the national GDP. The manufacturers of the prefab timber constructions belong to the timber sector, which creates about 1,3% of national GDP, and are there one of the highest value generating companies (59). They export almost the whole production (mainly Norway, Sweden and other Western countries), as the prefab timber construction in the local market is not very popular (60). The biggest competitive strengths of these companies are relative low labor costs and fairly modern manufacture devices used (59). In order to be able to execute bigger projects, 7 big timber construction producers have recently joined into a cluster „Energy efficient and passive buildings‟, which should promote contemporary timber construction methods and declares high cooperation with education institutions. The biggest problem for the timber sector today is the availability of the raw materials (60) (59), which is a quite contradictory situation regarding the fact that about 30% of the roundwood is exported (60). This is happens because the market prices of the raw timber are too high for the local companies, while being attractively low for the foreign ones.

The forests cover about a third of the Lithuanian territory. They slowly grow, as the laws of the sustainable forestry are adopted – the felled wood amount cannot exceed its annual growth, while the actual limits the Government defines each year (61). In practice only about a half of the annual wood growth (13,8 m m³) is felled (60).

2.8.2

Digital construction

Building Information Modelling (BIM) is a digital representation of physical and functional characteristics of a facility, which can be used for decision making during the life-cycle of the facility (2). This concept In order to reach a completely new quality in the construction by using the available digital methods, many countries around the world implement the concept of BIM. The circumstances for an intense implementation of BIM in Lithuania are favorable (62). Firstly, 35% of Lithuanian households had fibre-based high speed network access FTTH (1st in Europe, 9th worldwide) in 2014, while almost all other households have a broadband internet connection (63).

Secondly, higher education institutions incorporate the BIM-methodology in various study programs and many seminars are organized. Finally, the construction sector has foreign experience in countries, where the BIM-methods are more widely used. A public organization „Skaitmenine Statyba‟ („Digital Construction‟) creates and coordinates the national digital construction strategy, based on the openBIM methodology. It was established in 2014 and has been an observer of the „buildingSMART Nordic‟ association since 2015. The state has already approved the Lithuanian digital construction strategy, which should have been fully implemented until the year 2020 (62). Thereby the refurbishment sector is not treated separately. However, a relevant aspect of the digital strategy is the propagated BIM-employment in the public procurements (as proposed in the European Directive 2004/18/EC on public procurement and repealing), because today their requirements must be at least partially considered by purchasing the state-funded retrofit works (52).

55

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

2.9

SWOT analysis

In order to summarize the findings of the performed state-of-the-art investigation, a SWOT (threats, weaknesses, opportunities, strengths) analysis was made. Each component is divided to the thematic fields. These are taken from the typical sustainability assessment methodologies, like DGNB and are the following: Location, socio-cultural and functional, Environmental, Economic, Technical and Process.

Table 9 SWOT analysis Field Location Socio-cultural and functional

Environmental

Economic Technical

Process Field Location Socio-cultural and functional

Environmental Economic Technical

Process

Strengths Good location with developed public transport system, health and education facilities, green zones Individual residents initiatives for the enlivenment of the living space Loggias in each apartment Good size and proportions of the rooms Storage chambers in the basement High population density – rational use of the resources High expected life duration – benefits in the life cycle assessment District heat is produced mainly in the CHP plants District heating system Compact building form – low transmission losses through the building envelope Good technical condition and high load reserves of the structural elements, especially interior walls and floor slabs Apartment owner associations are often already established and can manage the occurring maintenance issues Weaknesses Low functional mixture – lack of services, culture facilities (job places) Safety situation, critical public image Poor esthetic quality: deteriorated surroundings, shabby façade appearance, abandoned green zones Poor floor plan layout quality: tiny kitchens and bathrooms, too small storage areas, loggias are used for storage, not for recreation No barrier-free accessibility, although a quarter of the population are pensioners Poor thermal comfort – no individual temperature control; too high or too low indoor temperatures due to the unbalanced heating system; draughts in case of the old leaky windows Poor air quality due to the insufficient natural ventilation Poor daylighting in the ground floor apartments Fossil fuels in the district heat production A considerable share of the residents is threatened with the fuel poverty because of high heat energy consumption Low real estate value of the apartments Thermal properties of the building envelope do not meet the current energy requirements Poor or even dangerous technical condition of parapets, balcony slabs and canopies Water absorptive exterior walls, especially the joints between the panels DHW circulation system is energy inefficient and questionable regarding the DHW hygiene Poor maintenance due to the collaboration issues of the apartment owners and their lacking feeling of responsibility for their own property The online accessible heat consumption values of the buildings do not represent their true thermal quality, due to the high gains from the DHW circulation system 56

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 2. State of the art

Field Location Socio-cultural and functional Environmental

Economic

Technical Process

Field Location Socio-cultural and functional

Environmental

Economic

Technical

Process

Opportunities Integral, state supported revitalization of the socialist housing estates Embracing the residents initiatives and demand for individuality for creation of better retrofit solutions Emergence of the tighter housing community – safety and responsibility Planned use of the renewable energy sources for the district heat production Employment of the local timber construction companies with lots foreign experience for the retrofits: use of local sustainable materials; propagate contemporary timber construction methods Existing high financial and administrative state support for the energy retrofits Additional funding for innovative demonstration retrofit projects might be obtained High value increase potential in case of full-scale retrofit and urban revitalization Use of prefabricated retrofit systems for the prefabricated buildings – high quality assurance Use of the emerging BIM-methods for more accurate, fair and transparent informing of the residents – rise the trust on the energy retrofit Use the potentials of the typical retrofit projects Reuse the installed relative new plastic frame windows Threats If the attractiveness of the large panel buildings and their districts does not increase, in the coming decades the high share of the seniors might be replaced by the residents with very low incomes, thus making the soviet districts deprived areas, continuing urban sprawl Seniors might be not interested in the energy retrofit measures, as they probably do not attain their payback, which could last up to 20 years Absence of the barrier-free accessibility becomes a critical problem, as the share of seniors increases Without effective ventilation solutions, the air quality may even worsen after the retrofit Oversized new biomass/waste CHP plants in case of the decreasing total heat demand (higher pace and quality of the energy retrofits + less new construction) Relative small share of the local fuels (biomass/waste) in the district heat production in case of increasing total heat demand (low pace and quality of energy retrofits + more new construction) No young families – irrational use of the existing education infrastructure and public transport system, continuing urban sprawl Large scale demolition and new development extremely irrational No total energy savings can be achieved with the energy retrofits if the intense urban sprawl continues: the energy use is relocated from the building sector to the transport Lowering financial resources of the residents for the retrofit Continuing and deepening of the fuel poverty Falling real estate value Quite long payback periods of the energy retrofit, low economic effect for the residents Wasted state investment in case of energy demand relocation to the transport sector Installation of the apartment-based energy accounting system leads to an uneven economic retrofit benefit for different apartments Continuing deterioration of the buildings – operation safety threatened Energy retrofit must include the DHW system, otherwise a sufficient economic effect cannot be reached Poor quality of the retrofit – maintenance may be soon required The private ownership of the apartments and the state ownership of the land hinder the municipality from taking effective actions on the revitalization Continuing poor maintenance of the building may lead to serious technical defects Good initiatives may fail due to the passive involvement of the residents Threatened public trust on the state retrofit program due to the inaccurate payback period estimations in the investment plans and poor design and workmanship quality 57

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3 3.1

Retrofit with prefabricated timber elements Targets

The performed analysis reveals that the present sociocultural and functional flaws are responsible for most of the other problems in large panel housing blocks. The similar conclusions were made in other studies (14). Therefore, these social and functional factors shape the proposed retrofit concept. The suggested solutions are based on the already discussed 5-storey apartment building with 1571 m² floor area, but can be easily adjusted for the other large panel buildings. Object of the retrofitting is the building; its surroundings are minimally affected.

The main target of the suggested retrofit is to adapt the house to the changing different residents´ needs on living space during the whole operation phase. Four age groups of the apartment owners are distinguished: young families with babies, families with school-age children, mature couples and pensioners. Their preferences for the living space are listed in the Table 10. In case of full adaption ability, the same dwelling could be used by few generations (Fig. 57). Such stable neighborhood would enable tight and long-lasting relations between the neighbors, which in turn simplify the collaboration on common house maintenance issues. At the same time, preservation of the middle class would mean more financial resources on these issues. Moreover, the urban sprawl would be limited and the existing infrastructure rationally used.

Table 10 Age groups of the residents and their living space preferences Group

Portion in total 26%

Age

Families with school-age children

41%

35-55

Mature couples

12%

55-65

Seniors

25%

65+

Young families with babies

25-35

Priorities -

Barrier-free accessibility because of prams; Decent kitchen; Low investment Decent kitchen; Max space for children; Outdoor space Cooking-dining-living area for guests; Outdoor space (gardening) Barrier-free accessibility; Gardening; Low investment

Fig. 57 Life cycle of the residents 58

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

The subgoals of the main target could are the following: 1. Involvement of the residents into the design.

2. Easy improvement of functional quality (including barrier-free accessibility) through horizontal space extensions. In ideal case, the individual solutions should be enabled.

3. High energy efficiency, which conforms to the objectives of Lithuanian energy strategy and eliminates the risk of fuel poverty. Due to the constant tightening of energy requirements for the new construction until the year 2020, a higher energy quality of retrofitted buildings may be preferred. This would reduce the quality difference between the retrofitted and new constructed buildings.

4. Cost-efficiency, because of limited residents‟ budgets. Cost-efficiency includes both decreased operation costs and increased real estate value. This should be achieved with an optimal investment. Thereby the available state support should be availed.

5. Increase air-quality. Find individual solutions for controlled ventilation system with heat recovery.

6. High workmanship quality.

7. Living of the occupants during the retrofit should be as least disturbing as possible.

8. More diverse, esthetically appealing exterior image.

9. Promote the innovative and sustainable construction methods.

3.2 3.2.1

Method Modularity

In order to achieve the defined objectives, an industrial modular retrofit system is introduced. Two types of retrofit measures are proposed: fixed and variable. To the first group belong construction of the exterior envelope (except windows), heating and DHW systems. The variable retrofit measures are called retrofit modules. They are windows, ventilation system and space extensions.

The retrofit modules have basic and advanced versions, which can be replaced by each other and implemented either in a single apartment or in the groups of them.

Every retrofit project must include all the fixed retrofit measures and a basic or an advanced version of every retrofit module. The basic retrofit package consists only of the basic versions. It requires the lowest initial investment, complies with the minimal requirements for energy performance and significantly enhances the technical condition of the building. The system generates a large number of possible retrofit modules combinations, which can be individually implemented. In this way, the final monotonic appearance is avoided despite the industrially produced building elements. Any of the retrofit modules can be implemented at once during the 59

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

main construction works, or added to the retrofitted building later. This means, the house can be step-by-step adapted to the changing needs and financial capabilities of the residents. The process is minimally restricted by collaboration issues, as decisions on bigger improvements can be made in small groups of 5 to 12 of the owners, so avoiding a full involvement of all residents of the house.

3.2.2

Workflow

3.2.2.1 Introduction Key elements of the retrofit system are the prefabricated insulated timber frame façade panels (TES Energyfacade). They are convertible, so allowing the horizontal space extensions even after the main construction works. Moreover, diverse building systems can be integrated into the panels.

The Timber Element System (TES) has been developed since 2006 and has already been applied in many energy retrofit projects. A typical TES-workflow is shown in the Fig. 58 and consists of the following phases (10): -

Survey including digital geometry measurements. A target is to form a reliable base for the further design. Due to the geometry capture a sufficiently accurate digital 3D façade surface model of the existing building is created. Thereby a wide range of measurement methods can be applied: photogrammetry, tachometry, 3D laser scanning (58).

-

Feasibility study. General economic perspective of the retrofit and design alternatives are accessed.

-

Design. The building information modeling (BIM) methods are employed. The digital building model is built on the prepared surface model of the existing facades. An active collaboration between the designers and manufacturers are required.

-

Element prefabrication. Digital models are directly read by the modern cutting machines like CNC and the required timber elements are produced with a high precision. Windows and the building system can be also integrated into the panels in the factory. Good conditions for quality surveillance are provided. All these factors ensure high product quality.

-

Transport. Maximal transportable element sizes must be defined in the design phase. For this, truck dimensions and obstacles on the way to the building site must be considered.

-

Assembly on site. Well preparation of the construction team is required for the fast assembly. As usually only the exterior envelope is retrofitted, the residents can stay at home during the construction works. It must be noted, that due to the consistent use of the created BIM-model through all the workflow stages, a well-documented ´as built´ model can be delivered to the building owner, who can use it for facility management purposes or future retrofits.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 58 Workflow in the TES-process (10) The typical TES-workflow is modified according to the proposed retrofit concept and the specifics of the prefab concrete buildings. The suggested process map is shown in the Fig. 59. Thereby three stakeholders are distinguished: digital or designer; residents; contractor or the production company. The map is horizontally divided into design stage, initial retrofit, further retrofits and endof-life phase. The diverse types of the components are shown in table below. Their location in the process map shows, who and when is responsible for the particular component.

Table 11 Explanation of the components of the process map Icon

Name Terminal

Description Signals the start of the workflow

Process

Shows that something is performed

Data input/output

Shows the required input for the process or displays the result of the process. Can be either digital (e.g. BIM-model) or real (e.g. building)

Decision

Shows where a decision is necessary, commonly a Yes/No question

61

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Typical existing building model

Residents

Contractor (Production Company) Typical prefabrication technologies

Typical residents’ needs

Retrofit design

Open source mass production technology

Typical retrofit project

Initial design

Digital (Designer)

All residents START Customization Delivery order

Existing building

Final customized project

Preparation and dismantlement

No

Reusable parts

Integration

Yes

Approved?

Assembly on site

´As-built´ model

Prefabrication

Retrofit elements

Initial retrofit

Retrofit configurator

Retrofitted building Willing residents START Customization

Final customized project

Approved?

Delivery order

No

´As-built´ model

Yes

Dismantlement and assembly on site

Prefabrication

Further retrofits

Retrofit configurator

Reusable parts Retrofit elements

Retrofitted building All residents

Deconstruction design

Agreement on demolition

Recycle Dismantlement/ Demolition

Energy

End-of-life

Reuse

Landfill

Fig. 59 Process map of the suggested retrofit system 62

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.2.2.2 Design The typical retrofit project is the essential part of the workflow. Thereby the potentials of the building information modeling (BIM) are employed. This solves the general problem of the typical project regarding the insufficient data and enables final user participation in the design. For this, the typical retrofit project is built as a parametric building model, which has two types of parameters. To the first group belong the parameters which describe the existing situation orientation, shading, technical condition and real energy consumption. They complete the required information input for the generation of retrofit results (static scheme, energy demand and economic forecast). It must be noted, that the technical condition of the building can be only accessed by the professionals. Other group of parameters defines the versions of the variable retrofit modules. By default, versions of all the modules are set to the basic (basic retrofit package). By changing these parameter values, the residents can easily explore the possible retrofit alternatives (various combinations of the retrofit modules versions) and compare their economic consequences, thus actively participating in the final design. In order to make the whole parameters-related process simpler for the people without specific knowledge, the typical retrofit project should be covered with a user-friendly interface, which is called a retrofit configurator. It could be a free-accessible online tool, similar to the existing vehicle configurators. Of course, the expert support should be still available.

As long-term data accessibility is of crucial importance, the whole digital process should be based on the neutral and reliable BIM standards. Such openBIM standards are created and continually developed by the international buildingSMART organization. Probably the most important is the IFC-schema (Industry Foundation Classes), which is used for the data description through the whole life cycle of a product and bases on the standard ISO 16739. As this data format is neutral and is supported by the most of the available BIM software tools, more and more national governments around the world requires BIM models in IFC-format for the public projects. As mentioned in the chapter 2.8.2, the Lithuanian digital construction strategy, which should be implemented until the year 2020, also bases on these open standards. As the energy retrofit receives a quite high state funding, a systemic use of the openBIM in the retrofit projects would be very welcome. For instance, detailed IFC models of different existing prefab building types could be created and put in a database for various purposes like retrofit or facility management.

3.2.2.3 Retrofit When all the residents complete the retrofit configuration on their apartment level, system checks, if all these configurations are compatible with each other, because some retrofit modules can be implemented only in particular groups of apartments. On this step, the certain decisions on implementation of these bigger retrofit modules should be made in the respective groups of the owners. If no agreeable majority is formed in any group, the residents may try to change the apartments with each other, so that the advanced retrofit module was implemented in at least one group. After all these optimization processes, the final parameter values are entered into the retrofit configurator and the final customized BIM project is generated. As the system should have already

63

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

been approved by the state, any generated model is automatically treated as an approved investment plan and a technical project at once.

The typical retrofit project suggests an open-source mass prefabrication technology of the main building elements. This can be employed in diverse production companies and their products and services could be proposed in the retrofit configurator, allowing the user to choose between the diverse offers. In ideal case, these companies could act as general contractors, which perform all the required prefabrication and construction works. Alternatively, the retrofit administrator could select separate companies for the separate construction works, but the prefabrication company still remains responsible for the major part of works. How to enable a mass production of the elements is further explained in the chapters 3.2.3 and 3.2.4.

In general, the order of required prefab façade elements is formed on the base of the generated BIM model and then sent to the production company. Meanwhile, the preparation works are done on site and the reusable dismantled parts are sent to the factory for integration into the new elements. When the building structure is prepared, the prefabricated elements are transported to the site and the new façade assembled. Finally, roof and basement are insulated and the new site topography formed. As the applied materials and exterior finishes can vary between the cases, the generated BIM model should be updated with this information for the future use.

3.2.2.4 Further retrofits When the residents decide to upgrade their house again, the updated BIM model is uploaded into the retrofit configurator so eliminating the need to entry the information about the existing conditions of the building. Combining the as-built model with the typical retrofit project, the further improvements can be explored and a new customized retrofit project generated. The residents or their groups, which decide on the improvements, should inform the other owners about their plans, so that they could also join and realize their own plans at once, thus saving some costs. Due to the initial retrofit works and acquaintance with retrofit configurator the apartment owners gain lots of experience. Therefore they should manage to order the construction works for the further improvements, which can be performed by single companies, without external help. In case of changing the basic retrofit module versions into the advanced ones, the old modules could be returned to the production company, which could use these modules in the other projects. As the system is conceptualized for such future developments and all the required information about it is documented in the existing IFC-model, the construction works last much shorter. The eventual deviations from the initial project must be again entered into the existing BIM model for the future use.

3.2.2.5 End-of-life The information level about the building during the whole operation phase can be easily maintained and even increased due to the integrated digital workflow. In case of radical reconstruction or the demolition of the building, the existing BIM model (long-term accessibility through IFC) can be used as a reliable data source for the deconstruction strategy. For this, special attributes regarding the 64

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

dismantlement and recyclability for the building elements can be created (64). These can be described under the IFC-category PropertySet. As a result, the building elements are properly disconnected from each other and used for the other purposes, saving the resources and energy, required for the new production.

3.2.3

Tolerances

A key-difference between the retrofit of individual and mass construction buildings is the need of digital geometry survey. In case of individual construction, the as-built and as–maintained conditions can differ from the existing construction plans considerably and the variations are usually not sufficiently documented. Therefore a detailed survey acts there as a precondition for the design. In case of prefabricated construction, the geometry deviations between the built structure and the existing plans are relatively small and can be ignored in the design of architectural modifications or energy efficiency. However, for the construction design the deviations might be still too big. The comparison between the allowed measurement tolerances for the typical TES system and the allowed deviations during the construction of the large panel concrete buildings is shown in the Table 12. Regarding the variations of the façade topography, the allowed measurement tolerances are almost equal to the total maximal design deviations (±8 and ±9 mm, respectively). However, only about two thirds of the accepted buildings were evaluated as satisfactory (5). In addition to this, additional deviations may occur during the operation years. As a result, the façade surface unevenness in places of panel joints probably exceeds the design values (Fig. 60). Nevertheless, even assuming that the panels are prefabricated with 100% accuracy, the allowed window position deviations along the horizontal axis are still by 5 mm higher than the measurement tolerances. It means, that a large panel with few windows cannot be prefabricated using the original design drawings.

Table 12 Measurement accuracy, allowed deviations and prefabrication tolerances

Allowed measurement accuracy for the TES system Allowed deviations during the construction of large panel concrete buildings (65) Achievable prefabrication tolerances

Z-axis (Normal to the façade plane) - Façade topography: ±8 mm

-

Vertical angle deviation over 2,70 m : ±5 mm Deviation from the horizontal axis: ±4 mm

XY plane (façade plane) - Windows: ±10 mm - Edges, corners: ±10 mm

-

Between two panels along the horizontal axis: -10 - +15 mm Total deviation between boundary axes: ± 30 mm Floor height: ±10 mm

±5 mm

65

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 60 Surface deviations of exterior walls: front and side façades In order to avoid the expensive measurements and enable mass production of the elements, the façade panels are designed for the adjustability on site. For this, two types of façade panels are introduced and shown in the Fig. 61. The major self-bearing façade panels cover the biggest part of the existing exterior wall. In places of the windows is a bigger than the window opening, where the panels of the second type are embedded. These consist of a window, framed by the exterior wall construction, and decentralized ventilation units. In order to enable an on-site adjustment of the elements to the actual geometry of the building, the gaps between the panels are left (Fig. 62).

Thereby, the arrows are showing possible movement direction. While the major panels can be moved only along the horizontal axis, the window elements can be precisely adjusted both vertically and horizontally. In order to adapt the TES panel to the existing structure surface, an adaption layer in-between is needed. All the gaps are filled with the insulation material afterwards.

However, for the actual gap size definition, the maximal façade geometry deviations are needed, which can be identified only due to the measurements of few representative buildings.

Fig. 61 Stacked façade panel structure 66

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Major facade panel Minor facade panel Opening in the existing facade

Fig. 62 Elevation view of the façade panel joints 3.2.4

Façade panel size definition

Fig. 63 possible façade panel layouts: horizontal (left) and vertical (right) There are two general principles for façade panels‟ arrangement: horizontal and vertical (Fig. 63).

Each of them has its advantages and disadvantages, which are summarized in the table below.

According to the accessible information of the Lithuanian timber companies, the maximal panel dimensions using typical manufacture and transportation devices are about 3,00 – 3,20 m in height and 13,00 – 13,60 m in length.

Table 13 Comparison between the horizontal and vertical façade panel arrangement

Pro

Horizontal arrangement Smaller elements (height 2,70 m, length 3,20 – 9,60 m) - Manufacture with standard equipment possible - Relative simple transportation (lowbed truck is needed anyway – see Fig. 64) - Usage of glulam timber elements can be avoided Segmentation according to the apartment units possible - Good sound insulation - Adaption of separate elements to the individual preferences

Vertical arrangement Building-height elements (width 3,20 m, height ~14,60 m) - Simple integration of building systems (vertical heat distribution pipes, ventilation, DHW, etc) - Shorter assembly on site time - Less disturbance for residents - Simple horizontal extension (only a single element needs to be converted) Small number of element types - Suitable for mass production - Mass-production enables costefficiency of special solutions for equipment and transportation 67

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Contra

Lots of joints - Longer assembly on the site - Limited possibilities for installation of central building systems (vertical heat distribution pipes, ventilation) - Complex process of vertical extensions on further development stage, because more elements need to be dismantled More element types – more difficult for mass-production

Panel dimensions exceed standard dimensions of production and transportation equipment; Because lack of space, the elements cannot be transported through common ways in courtyards; Bigger crane is needed; More expensive glulam timber must be used for the long vertical studs; Scaffold can be placed only on the both sides of the façade panel, in order not to block the mounting process.

To sum up, the vertical arrangement has more advantages regarding residents comfort and technical quality, because of shorter assembly on site duration and high prefabrication scale possible. Regarding the production and transportation phase, the horizontal arrangement is clearly better. Prefabrication and transportation of large vertical elements seems to be viable only in case of mass-production or a large-scale Retrofit of a whole residential quarter. The municipalities declare that such large-scale urban revitalizations should become a common practice in the near future. Therefore, only the vertical arrangement of the elements was further analyzed in this study.

Fig. 64 Passage between courtyards – the main restriction for transportation of large prefabricated elements 3.2.5

Static scheme

On design of the static scheme, few factors must be considered. Firstly, an independent dismantlement of the separate large façade panels must be enabled without threatening the general structural reliability of the building. Secondly, the existing load reserves of the building must be taken into account. The vertical panels transfer their vertical loads to the base, while the lateral loads are taken by the existing floor slabs and transverse interior walls through the horizontal anchors. As already stated in the chapter 2.4.2.1, the buildings structural reliability normally is not threatened and big load reserves are available, especially regarding the interior constructions. Therefore, additional lateral loads should not cause any static problems. However, because of possibly high deterioration of the element connections, the structure might be still 68

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

incapable to take additional vertical loads or must be even additionally strengthened. In case of whole-building-high TES-panels, only the base joint between basement walls, ground floor slab and exterior walls must be accessed. For both possible cases (sufficient and insufficient load reserves of the base joint) two different strategies of load transfer must be developed.

Finally, it must be considered that due to the fire safety requirements (chapter 2.5.2), the load bearing elements of typical multi-family houses cannot be made of wood. This regulation affects the following construction points: -

Space extensions

-

Balconies‟ construction, where separate steel construction is added to the exterior of the respective TES-panels

These two points are further analyzed in the static schemes.

3.2.5.1 Sufficient load reserves

Fire-proof loadbearing side walls and floor slabs

Load transfer to the existing foundation

Replacement

Load transfer to the new foundation

Fig. 65 Static schemes in case of sufficient load reserves for space extensions Increased lateral loads to the existing structure Vertical load transfer to the new exterior columns

Added fire-proof balconies Fire-proof loadbearing exterior columns

Fig. 66 Static scheme in case of sufficient load reserves for balconies The suggested static schemes in case of sufficient load reserves are presented in the Fig. 65 and Fig. 66. Thereby, the existing structure is shown in white, the self-bearing TES-panels – in green, and the load bearing fire-proof structures – in red. The loads, which are transferred to the existing structure are marked in black, the loads that are taken by a new structure are shown in red. In 69

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

order to maintain the not-load-bearing function of the replaced TES-panels, the loads of the space extensions are transferred to the new fire-proof side walls and are distributed to the new and the existing fundament at the base. Due to the addition of the balconies the increased lateral loads are transferred to the existing structure. The vertical loads are taken by steel columns, which are mounted on the exterior surface of the respective TES-panels. They are included already in the basic version of the retrofit, so that an individual addition of the balconies would be possible any time. A tension rod construction is selected in order to avoid other supporting constructions.

The TES-system suggests various variants of the façade panel connection to the base (Fig. 67).

For this, the existing footing, the basement wall and the basement ceiling can be used. The least invasive method is the shown in the second picture. Thereby, the vertical loads are transferred to the basement wall through L-bracket with a sill beam. This steel element is simply anchored to the wall at a required location. In case of unreliable wall material condition in that place, the existing material can be replaced with concrete.

Using old footing

Using old wall

Using old wall + ceiling

Fig. 67 Possible TES-element connections to the base in case of sufficient load reserves (66) 3.2.5.2 Insufficient load reserves The static schemes in case of insufficient load reserves differ from the previously discussed only regarding the vertical load transfer at the base point. Thereby, the vertical loads are transferred to the new structure, and the existing building structure takes only the lateral loads. The possible construction solutions for this new fundament are shown in the Fig. 70. A new strip footing, a footing with micro-bored piles or a combination with a balcony fundament may be viable. In our case it can be reasonable to implement the third variant in places, where space extensions are planned and the first solution in the all other places.

70

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fire-proof load-bearing side walls and floor slabs

Load transfer to the new foundation

Replacement

Load transfer to the new foundation

Fig. 68 Static schemes in case of insufficient load reserves for space extensions Increased lateral loads to the existing structure Vertical load transfer to the new exterior columns

Fire-proof loadbearing exterior columns

Added Fire-proof balconies

Fig. 69 Static scheme in case of insufficient load reserves for balconies

New strip footing

New footing (micro bored piles)

Combination of footing façade + balcony

Fig. 70 Possible TES-element connections to the base in case of insufficient load reserves (66)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.3

Typical retrofit project

The key-element of the process – typical retrofit project – is created, in order to test the feasibility and efficiency of the proposed system. It is intended for the already inspected large panel building type 1-464LI-18/2 (5-storey, 30-unit block) but can be easily modified for the other 5-storey building types of the series 1-464LI. Thereby fixed retrofit measures are designed together with the both versions of the retrofit modules, thus specifying the full data content for the further configuration.

3.3.1

Preliminary energy calculations

In order to define the most influential factors on the energy consumption after a retrofit, a preliminary energy analysis was performed. The same software tool – PHPP was used. In the preliminary calculations only the minimal retrofit measures according to the building class C were implemented. These measures are shown in the Table 14.

Table 14 Implemented retrofit measures for the preliminary energy calculations General properties Treated floor area (PHPP), m² Occupants Total air exchange rate n, 1/h PHPP climate dataset

1620,7 75 0,50 Central Europe – [LT] Vilnius

Volume, m³ DHW l/(Pers.*day) Ventilation volume, m³ Interior air temperature, °C

5690 25 4324 20

Building elements Area, m²

U-values, W/(m²K)

Exterior walls facing the exterior air Exterior walls facing the glazed loggias (100% of the loggias glazed) Basement walls Roof Basement ceiling

670,55 244,80

0,21 0,21

Temperature factor, 1,00 0,85

34,34 400,71 400,71

0,26 0,16 0,16

0,66 1,00 0,66

Windows

237,09

1,34

1,00

Heating pipes

603,4 m

0,14 W/(mK)

0,66

DHW pipes

366,4 m

0,14 W/(mK)

0,66

The preliminary energy analysis results are shown in the diagrams below. The final energy savings for the heating and domestic hot water are almost 50%. As the energy source (district heating) remains the same, the final costs are also reduced by almost a half. Comparison of the final energy balances between the existing building and the retrofit shows, that due to the insulation of the heating and DHW pipes about 30 kWh/m² can be saved. The improvement of the thermal envelope adds further 80 kWh/m² to the savings. However, the ventilation losses are increased, assuming that a required air-exchange in the premises is ensured. Regarding the transmission losses, a relative high influence of the thermal bridges attracts attention. This happens due to the not removed thermal bridges around the balcony slabs. About a half the transmission losses happens through the windows. It must be noted that the indoor air temperature after the retrofit is higher 72

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

(20°C instead of 18°C); therefore the energy savings are lower than it could be expected. The preliminary energy analysis reveals that the ventilation, windows and thermal bridges have the highest further energy saving potential. In contrast, due to the predefined measures a quite high thermal quality of the exterior walls, roofs and basement ceiling is achieved. Thus, additional insulation measures would have a relative low energy saving potential.

250

206

200 139

150

kWh/(m²a)

118

Existing

75

100

C preliminary

50 0 Space heating

Final heat

Fig. 71 Comparison of final heat energy and space heating energy: existing conditions and preliminary retrofit according to the minimal requirements of the C class building Losses DHW Demand

160 140

DHW system losses

120 kWh/(m²a)

Heating system losses

Gains

100

Ventilation

80

25,9 6,8 9,3

32,6

85,2

final DHW

final heating

43,0

60

Solar gains

40 60,7

Transmission

20

16,5

0

11,3 1

Internal gains

1

Fig. 72 Detailed final energy balance of the C-class building after the preliminary energy analysis Thermal bridges; 6,8

Exterior walls; 9,0 Basement walls; 0,4

Doors; 0,7

Roof; 4,1 Basement ceiling; 5,1

Windows; 31,2

Exterior walls loggias; 2,8

Fig. 73 Transmission losses of the C-class building 73

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.3.2

Layout

3.3.2.1 Retrofit module K: Horizontal kitchen extension

Fig. 74 Existing situation (L0+K0) and Retrofit steps (L1+K1; L1+K2; L2+K2) of living-diningcooking area Table 15 Retrofit module K: summary

Functional improvement Additional floor area in reference to the existing conditions (per single apartment) Minimal amount of involved apartments Drawbacks

K1 Slightly more place for dining table 0,47 m²

K2 Decent dining area for 4 persons with good daylight 4,02 m²

The whole house (initial retrofit)

5 apartments (on top of each other)

Slightly reduced daylight

The remaining part of the concrete wall blocks the daylight in the rear part of the kitchen Floor slab area: 17,2 m² Roof area: 4,30 m² Ground floor slab area: 4,30 m² Side panel area: 42,00 m² Side windows area: 7,70 m² 1 x Kitchen panel PK (offset) 5 x Kitchen window WK (offset) 1 x Space element for ground floor SPK_1 3 x Space element for regular floor SPK_2 1 x Space element for roof SPK_3 200 EUR/m² floor area (typical prefab timber house price – 200 EUR/m²)

Main construction works (per single module)

Dismantled concrete: 2,05 m³ Concrete cut: 38,10 m Addition of the façade panel PK

Involved room bounding elements (per single module)

1 x Kitchen panel PK 5 x Kitchen windows WK

Assumed price

Included in the basic price

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Fig. 75 Process: retrofit modules K1 and K2

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Existing conditions

Retrofit package 1 (basic)

Retrofit package 1+WK

Retrofit package 1+WK+K

Fig. 76 Daylight analysis for a north oriented kitchen in the ground floor

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3.3.2.2 Retrofit module L: Horizontal living room extension

Fig. 77 Retrofit steps for the living room: existing situation (L0), horizontal extensions L1 and L2 Table 16 Retrofit module L: summary

Functional improvement

L1 Slightly more floor area

L2 Connection with the dining area – a common living space created; Only in combination with the K2 5,52 m²

Additional floor area 0,72 m² in reference to the existing conditions (per single apartment) Minimal amount of The whole house (initial retrofit) 5 apartments (on top of each other) involved apartments Drawbacks none Substantial daylight reduction in the back of the room; Reduced daylight in the kitchen Main construction Dismantled concrete: 3,05 m³ Floor slab area: 17,2 m² works (per single Concrete cut: 46,35 m Roof area: 4,30 m² module) Addition of the façade panel PL Ground floor slab area: 4,30 m² Side panel area: 20,25 m² Dismantled side panels of the space modules SPK: 20,25 m² (including 7,70 m² window area) Involved room 1 x Living room panel PL 1 x Living room panel PL (offset) bounding elements 5 x Living room windows WL 5 x Living room windows WL (offset) (per single module) 1 x Space element for ground floor SPL_1 3 x Space element for regular floor SPL _2 1 x Space element for roof SPL _3 Assumed price Included in the basic price 200 EUR/m² floor area (typical prefab timber house price – 200 EUR/m²)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 78 Process: retrofit modules L1 and L2

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Existing conditions

Retrofit package 1 (basic)

Retrofit package 1+WL

Retrofit package 1+WL+L+K

Fig. 79 Daylight analysis for a living room in the ground floor

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.3.2.3 Horizontal extension of a room with loggia

Fig. 80 Retrofit steps of the bedroom: R0 (existing), R1 and R1+B (with balcony) Table 17 Horizontal room extension: summary

Functional improvement

Additional floor area in reference to the existing conditions (per single apartment) Minimal amount of involved apartments Drawbacks

Main construction works (per single module) Involved room bounding elements (per single module) Assumed price

Room – retrofit Large bedroom created – the rear part can be used for storage and wardrobe; Improved daylight; Solved problem with thermal bridges; Compact building form - 3,60 m² loggia + 3,83 m² + 0,60 m³ winter garden

Room +B Exterior space - balcony; Connection with the kitchen K2 from side is possible in the 2+1B apartments.

The whole house (initial retrofit)

Single apartment (not available in the ground floor) Not barrier-free accessible balcony because of daylight preservation in the apartments below; Additional privacy screens required.

Balcony area: 1,67 m²

Removed outdoor space (loggia) is replaced with much smaller winter garden Dismantled concrete: 3,30 m³ Concrete cut: 62,35 m Addition of the façade panel PR 1 x Room panel PR 5 x Room windows WR 5 x Balcony doors WB Included in the basic price

- 3,60 m² loggia +3,83 m² + 2,27 m² balcony (including 0,60 m³ winter garden)

1 x Balcony B 150 EUR/m² balcony area 80

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

The retrofit of a room with the loggia and balcony module are analyzed together. Because the existing loggias are already very narrow, the additional insulation layer on the exterior walls would make them unusable (about 100 cm wide), and lots of loggias are even now not used for recreation purposes. Moreover, it needs lots of effort to insulate the balconies without thermal bridges.

Therefore, it is suggested to close loggia with a single façade panel and leave only a small winter garden. On demand, a balcony can be individually added to the structure. Its geometry is formed in such way, that the daylight for the apartment below is not restricted (Fig. 81).

Fig. 81 Design of the balconies regarding the daylight situation in the existing and retrofitted building (section of the 1st floor)

Fig. 82 Process: retrofit modules R1 and R1+B 81

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Existing conditions

Retrofit package 1 (basic)

Retrofit package 1+B (above)

Retrofit package 1+WR+B (above)

Fig. 83 Daylight analysis for a bedroom in the ground floor As already mentioned in the chapter 3.2.5, a tension system is chosen for the balcony. The building-height steel columns are attached to the exterior surface of the façade panel PR and take the vertical balcony load, while horizontal anchors are fitted into the existing concrete floor slab and 82

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

takes the lateral loads from the façade panel and the balcony. These anchors have rings on their ends, which are intended for the attachment of the steel cables of the balcony. On the base, the balcony slab is embedded into a horizontal slot made from a steel channel and then fixed with bolts. These slots are located in horizontal partitions between the balcony windows of separate apartments and are by default covered with a removable metal sheet. In this way, the load bearing structure of the balcony can be simply installed from the inside of the apartment. The railing and privacy screen can be later added by standing on the mounted slab. The load bearing parts of the balcony should be prefabricated, so that a high structural reliability is ensured. The installation works can be basically performed by the residents on their own.

Fig. 84 Structure of a individually attachable balcony (Retrofit module B)

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3.3.2.4 Retrofit module BF: Barrier-free accessibility Table 18 Retrofit module BF: summary

Functional improvement

Additional floor area in reference to the existing conditions (per single module) Minimal amount of involved apartments Drawbacks

Main construction works (per single module)

Involved room bounding elements (per single module) Assumed price

BF1 Enlarged entrance; Entrance to the basement from the inside; Site level increase by 90 cm: - 20% of the apartments (the whole ground floor) almost barrier-free accessible through the terraces - Concrete reuse for landfill 7,38 m²

BF2 Elevator - all apartments almost barrierfree accessible

The whole house (initial retrofit)

12 apartments in single building section (ground floor apartments not included) Relative high investment; For a full barrier-free accessibility an inclined platform lift and widening of the all apartment walls is needed; Dismantled timber frame panels: 9,85 m² Installation of the prefab elevator shaft

For a full barrier-free accessibility an inclined platform lift and widening of the all apartment walls is needed; Lots of ground works Dismantled concrete: 6,79 m³ Concrete cut: 33,62 m Installation of elevator base shaft (concrete) Addition of the façade panel PS Stairway landings: 7,38 m² 1 x Stairway panel PS (with windows) 4 x Stairway landings Included in the basic price

7,38 m²

1 x Prefabricated elevator shaft 20000 EUR

The proposed retrofit measures primarily intend to significantly improve the accessibility of the building for the seniors and young families with baby buggies. The entrances to the elevator and to the flats are still not on the same level. However, the remaining stair run should be unproblematic for these target groups, especially as only downwards direction can be used. Although the owners cannot expect financial government support for an elevator, it would considerably improve living quality and the market value of their apartments.

Although the proposed retrofit modules does not provide a full barrier-free accessibility for disabled people, the convenient conditions are created for this. In order to achieve a full barrier-free accessibility all the apartment doors must be widened and an inclined platform lift in the stairway must be installed. The elevator is already suitable for the wheel chair.

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Fig. 85 Retrofit steps of entrance area: BF0 (existing), BF1 (basic), BF2 (with elevator) 85

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 86 Process: retrofit modules BF1 and BF2

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3.3.3

Constructions

3.3.3.1 Exterior wall The façade elements are either mounted directly on the existing exterior walls (Type EW1), or act as single room bounding elements (Type EW2). The later happens in places where the existing façade was removed. As these are the weakest points of the façade regarding thermal properties and fire safety, they must meet the legal requirements for exterior wall. Additionally, the following aspects must be considered: -

Minimal element thickness is preferred, in order to reduce the negative effect on the daylighting.

-

Air tightness. Unregulated exterior air infiltration must be prevented. Thereby the vertical panel joints should be accessed in detail.

-

Hygrothermal performance. The existing structure may contain high amounts of water. An effective drying must be enabled, in order to prevent the accumulation of humidity in the structure, which would result in structural damage.

-

Mounting and dismantling process of the panels. Prefabrication level of the panels must be as high as possible, the construction works on site minimized and simplified.

The both types of the exterior walls are shown in the Fig. 87. There a horizontal section of the exterior wall below the window is presented. The prefabricated part of the construction is marked in red, the existing structure is black and the on-site mounted elements are green. The frame of the TES-element is made of glulam timber with typical section dimensions of 160 x 60 mm. The timber frame is covered with OSB3 board from the interior and a hard mineral wool isolation board from the exterior side. As the heating pipes are also installed in the panels, many small cavities remain.

Therefore the blow-in thermal isolation is used for the infill. Locally produced cellulose is available on the Lithuanian market. Its price is similar to the mineral wool. Moreover, the local material has clearly less embodied energy. The environmental impacts during the life cycle are however not accessed in detail.

In case of type EW1, the existing structure (total sd-value 4,1 - 8,2 m) acts as a vapor retarder and an air-tightness layer. For this, the existing leaky joints are cleaned and filled with an elastic sealant. In EW2 these functions are performed by the OSB-board. It acts as an ordinary vapor barrier on dry conditions (sd-value over 4,0 m on 50% relative humidity) and allows the drying of the construction inwards if it gets wet (sd-value less than 1,0 m on 75% relative humidity) (67).

In order to ensure the fire resistance, the interior side of the room bounding elements is covered with gypsum board sheeting. Moreover, the installation layer and the areas around the openings are filled with a mineral wool.

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EW2

EW1

Fig. 87 Exterior wall, plan view: EW2 (left); EW1 (right) Table 19 Exterior wall construction: TES-element on the existing wall (type EW1) Nr. 1 2

Layer

Existing – concrete render Existing – expanded clay lightweight concrete core 3 Existing – concrete render 4 Adaption layer – blown in cellulose Timber batten for horizontal fixation, 100 mm, 2,70 m 5 OSB board 6 Thermal insulation – mineral wool Glulam timber frame 160 x 60 mm, 530 mm 7 Hard thermal insulation – mineral wool 8 Plaster Total thickness, mm U-value, W/(m²K) Assumed price, EUR/m²

Heat conduction λ, W/(mK) 1,20 0,480

Thickness, mm

Share, %

Vapor diffusion thickness sd, m

15 260

100 100

1,05 - 2,10 1,30 - 2,60

1,20 0,035 0,13

25 50

100 97 3

1,75 - 2,50 0,05

0,13 0,035 0,13 0,035 1,0 560 0,161 90

22 160

100 82,1 17,9 100 100

1,00 – 4,00 0,16

20 8

0,02-0,06 0,06

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Table 20 Exterior wall construction: TES-element as exterior wall (type EW2) Nr.

Layer

1 2

Gypsum board Installation layer – mineral wool Timber studs 35 x 35 mm, 625 mm 3 OSB board 4 Thermal insulation – mineral wool Glulam timber frame 160 x 60 mm, 530 mm 6 Hard thermal insulation – mineral wool 7 Plaster Total thickness, mm U-value, W/(m²K) Assumed price, EUR/m²

Heat conduction λ, W/(mK)

Thickness, mm

Share, %

0,485 0,035 0,13 0,13 0,035 0,13 0,035 1,0 260 0,193 90

12,5 35

100 95,2 4,8 100 82,1 17,9

22 160 20 8

Vapor diffusion thickness sd, m 0,15-0,30 0,035 1,00 – 4,00 0,16 0,02-0,06 0,06

Fig. 88 Mounting process of the TES-panels The mounting process of the façade panels is shown in the Fig. 88. The following work steps are used for the both types of the exterior walls: 1. The existing joints are cleaned and sealed 2. Timber battens 100 x 40 mm for horizontal panel fixation are mounted at the level of the floor slab 89

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3. The TES-panels are anchored to the timber battens using the screws. The holes in the studs of the TES-panels are pre-drilled.

4. The overlapping air-tightness membranes are connected to each other with a sealant 5. The resulting gap between the panels is filled with a mineral wool 6. The gap size between the TES elements is variable, as it depends on the actual deviations of the existing façade. Therefore, the required form of the hard wool covering is cut on site.

On one side it has an already finished rabbet. The required profile on the other side is formed in two steps: the actual width is defined with a first straight cut; the rabbet is made with a router on a second cut 7. Render is applied 8. Interior surface a. TES-element on the existing wall: the cavity between the existing and TES- façades is filled with the blow-in isolation b. Single TES-element as a façade: an installation layer is mounted The resulting joint can be simply dismantled on demand, as only the cap and the anchor screws must be removed.

The whole assortment of the used façade panel types is presented in the Fig. 89. The timber frame is marked in dashed lines. The panels PR and PS include windows. For the building corners and parapets special types of small prefabricated façade panels are proposed, in order to ensure easy handling and fast assembly works.

Fig. 89 Façade panel types

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Table 21 Façade panel types: summary Code PK

Area of application Kitchen

Dimensions, m 3,20 x 13,45

Area, m² 28,64

Required amount 6

PL

Living room

3,20 x 13,45

20,57

7

PR

Bedroom

3,20 x 13,45

16,71

4

Possible changes Convertible (in K2) Convertible (in L2) Immutable

PR‟

Bedroom, mirrored

3,20 x 13,45

16,71

3

Immutable

PS

Stairway

3,20 x 14,43

34,03

2

PSW PK PP_1

Side wall Corners Parapet wall

2,98 x 13,45 0,49 x 2,70 3,20 x 0,40

41,72 1,32 1,28

5 15 22

PP_2

Parapet wall, side 9 panel types

2,98 x 0,40

1,19

5

Immutable, removal of 9,59 m² panel area for elevator doors (BF2) Immutable Immutable Moves with the host panel Immutable

Total area

735,86

Total

Hosted modules Heating H Windows WK Heating H Windows WK Heating H Windows WR Windows WB Balcony B Heating H Windows WR Windows WB Balcony B Elevator E

none none none none

In order to get an idea about the possible construction price, a brief research on similar construction prices on the Lithuanian market was performed. The results are summarized in the Table 22. Typical finished timber frame wall construction costs about 70 EUR/m², while a typical mineral wool-based composite heat insulation system costs about 78 EUR/m². Assuming a worst case scenario, the total price of the rendered TES-façade, including mounting works and transportation, could be about 90 EUR/m².

Table 22 Research on the exterior wall prices Construction TES panels – pre-estimated material costs Timber frame wall, rendered, only construction works Timber frame (145x45x625 mm) wall, mineral wool, finished on both sides Composite heat insulation system: mineral wool, rendered Assumed total price for TES-facade

Price, EUR/m² of construction 25,53 25 70 78

Source Various internet shops http://www.karkasinis.lt/?Kainos Company „Skado medis“, personal inquiry Investment plans

90

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3.3.3.2 Roof R

Fig. 90 Roof joint with the TES-panel The roof and façade panel joint is shown in the Fig. 90, where the prefabricated elements are marked in red, the existing structure – in black and the elements, which are mounted on site – in green. It is proposed to remove the existing insulation (gas silicate panels) together with the deteriorated parapet blocks. Thus, the cavity between the existing insulation blocks and the concrete slab can be completely cleaned and possible structural damage on the construction due to the already infiltrated humidity or other not visible defects prevented. In addition to this, the total height of the building is slightly reduced, so not hindering daylight to the neighbors. The final weight of the roof is also reduced, so increasing the load reserves of the whole building structure.

Deconstructed materials are used for landfill on the site, so saving the disposal costs. According to the investment plans, typical cleaning, insulation and sealing works costs are about 71 EUR/m².

The deconstruction costs and additional cleaning of the slab could ad about 20 EUR/m² to this.

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Table 23 Roof construction Nr.

Layer

1 Existing – prefab concrete slab 2 PE-foil 3 Cement screed wit slope (lowest - highest point) 3 Thermal insulation – PUR with slope (lowest - highest point) 4 Bitumen layer 5 Loose gravel Total thickness, mm U-value, W/(m²K) Thermal bridge roof – exterior wall Deconstructed concrete, m³ Assumed construction price

Heat conduction Thickness, λ, W/(mK) mm 1,200 100 1,200 0 - 70 0,024 140 - 190 10 40 280 – 400 0,165 0,054 W/(mK) 93,6 m 152 71 EUR/m²+ 30 EUR/m³ for deconstruction

According to the standard EN ISO 10211, mold occur at the surfaces, which temperature factor f*Rsi is lower than 0,70. This factor is calculated using the equation

where: θe – outdoor air temperature, °C, θsi – interior surface temperature, °C, θi – indoor air temperature, °C. For the thermal bridge calculations the standard sets the outdoor air temperature to -5°C, while the air temperature indoors is assumed to be 20°C and the relative indoor air humidity is 50%. The mold formation then can be expected on the colder than 12,6 °C interior surfaces. The temperature distribution at the joint is simulated using the software Therm 6. The temperature curves and calculation scheme with boundary conditions are shown in the Fig. 91. Thereby the critical 12,6 °C isotherm is marked in red. It is seen, that it does not occur on the interior surfaces, so mold formation is not expected at this point.

A linear thermal bridge coefficient at the joint of two building elements is calculated using equation

where: Ψ1-2 – thermal bridge coefficient at the connection of the building element 1 and 2, W/(mK), UTB – heat transmission coefficient of the building element at the thermal bridge, calculated by the Therm 6, W/(m²K), U – normal heat transmission coefficient heat transmission of the building element, W/(m²K), 93

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

lTB – length of the thermal bridge of the first building element from the interior side (until the temperature curves become parallel to the construction – constant heat flow), m.

The respective values of these parameters are shown in the Fig. 91. The calculated thermal bridge coefficient at the parapet is 0,082 W/(mK), which is less than the required 0,19 W/(mK) for the Lithuanian building class C. The same formula is used for the thermal bridge calculations of the constructions.

Fig. 91 Roof and façade panel joint: temperature curves and thermal bridge calculation

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Fig. 92 Mounting process of the roof and TES-panels

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3.3.3.3 Basement ceiling

Fig. 93 Base joint Table 24 Construction of the basement ceiling Nr.

Layer

1 2 3 4 5 6 7

Existing – wooden flooring Existing – cement screed Existing – sound insulation Existing – prefab concrete slab PE-foil Thermal insulation - PUR Render Total thickness, mm U-value, W/(m²K) Assumed construction price, EUR/m²

Heat conduction λ, W/(mK) 0,130 1,200 0,045 1,200 0,023 1,2 270 0,274 52

Thickness, mm 21 48 25 100 70 6

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In the Fig. 93 a base joint in case of sufficient load reserves is presented. The base support is Lsteel bracket, which is anchored to the basement wall. The joint is detachable – only a small strip of thermal insulation needs to be removed in order access the TES-panel fixation screw.

The thermal bridges were evaluated with software Therm 6. It is seen, that the critical point at the base is at the end of steel support. Therefore, a more effective thermal insulation (Polyurethane foam) is used in this point. Insulation of the basement ceiling in multi apartment buildings is problematic in many points of view. Insulation from the top of the slab is very invasive and thus hardly possible. Additional isolation layer from the bottom of the slab reduces the basement height, which is already quite low (2,02 m). The solution is to use more effective insulation material. Other problem is a number of thermal bridges along the load-bearing interior basement walls and the plinth. The energy losses through these spots can be reduced by adding insulation stripes on the basement walls. Their section is a form of a triangular, as this corresponds to the temperature curves in the construction. Triangular insulation stripes also saves material. The residents must also provide an access to their basement storage chamber for the workers and ensure, that no obstacles are blocking the places, were the insulation boards must be mounted. As these storage chambers are normally full of stuff, this task may also prove problematic.

Nr.

Thermal bridge Connection interior walls basement – ground floor Wall plinth Total area of construction, m²

Heat transfer coefficient ψ, W/(mK) 0,059 0,063 450

Total length, m 151,5 93,56

Fig. 94 Temperature simulation and definition of the thermal bridge on the base joint 97

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Fig. 95 Temperature simulation and definition of the thermal bridge on the connection between interior walls in the basement and ground floor 3.3.3.4 Windows

Fig. 96 Main components of the double window Replacement of the quite new windows could appear an inacceptable solution for the owners, because of additional costs and effort. However their thermal properties are usually slightly worse than currently required for C-class buildings (Uw = 1,34 W/(m²K)). The windows of passive house must be two times more efficient. In addition to this, the current position of windows would cause a thermal bridge around the frame after the façade insulation. In order to improve the thermal 98

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

performance of the windows without changing them, double window system is proposed. It consists of the existing window on the interior side and an additional glazing on the exterior side.

The resulting gap works like a mini winter garden.

The windows have two different retrofit modules. The first module is called windows quality (code WQ). Thereby the thermal properties of the existing window form the basic version. For the advanced version of module WQ typical properties of new windows are selected. The second module describes the window size (code W). For the basic version the height of the existing window is selected, while the windows in the advanced version are higher. It must be noted that the implementation of the advanced retrofit module WQ means only a replacement of the inner window, while to the retrofit module W belongs the whole double window structure, including the frame. The basic parameter values are summarized in the table below. It is seen, that a detailed assessment of the windows is needed because the installation thermal bridge coefficient and temperature reduction factor depend on many other factors.

Table 25 Retrofit modules of the windows and their parameters Module Code WQ

W

Module name Windows quality

Window size

Parameters Heat transmission coefficient of the inner window frame Uf, W/(m²K) Heat transmission coefficient of the inner window glazing Ug, W/(m²K) Thermal bridge around the inner window glazing Ψg, W/(mK) Installation thermal bridge of the inner window Ψi, W/(mK) Solar heat gain coefficient of the inner window g, Temperature reduction factor Tf, Window height, m

Basic version 1,80

Advanced version 1,30

1,60

1,10

0,04

0,03

Dependent on the installation position 0,70 0,60 Dependent on window size, location and ventilation - 1,45 - 1,88 (2,07) - 2,12 - 2,50

3.3.3.4.1 Installation Two window installation alternatives are analyzed in focus on the thermal bridges. In the first case, the interior window surface is aligned to the interior surface of the TES-element (OSB board). This is the simpliest way of installation. In the second alternative the window is aligned to the exterior surface of the existing wall. For the both installation variants, both window quality types are used.

Due to the calculations an installation thermal bridge coefficient is identified for the further use in energy analysis. Moreover, the possibility of mold formation is accessed.

The thermal simulation was performed using the software Therm 7.3. The thermal properties of the exterior wall elements are taken from the Table 19. Window frame and the glazing are simplified, because the analysis focuses on the general flow of the isotherms in the junction. Values for the thermal conductivity of the frame and glazing are calculated in such way, that the resulting Uvalues of the particular elements remain as required – see Table 26.

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Table 26 Thermal conductivity values of window elements for the simulation with Therm 7.3 WQ

Element

Thickness, mm

Required Uvalue, W/(m²K)

Heat conduction λ, W/(mK)

Rsi, m²K/W

Rse, m²K/W

1

Frame 65 mm, no exterior glazing Frame 65 mm, with exterior glazing Glazing 20 mm, no exterior glazing Glazing 20 mm, with exterior glazing Frame 65 mm, no exterior glazing Frame 65 mm, with exterior glazing Glazing 20 mm, no exterior glazing Glazing 20 mm, with exterior glazing Exterior glazing 5 mm

65

1,8

0,1686

0,13

0,04

65

1,8

0,1527

0,13

0

20

1,6

0,0440

0,13

0,04

20

1,6

0,0404

0,13

0

65

1,3

0,1085

0,13

0,04

65

1,3

0,1017

0,13

0

20

1,1

0,0271

0,13

0,04

20

1,1

0,0257

0,13

0

5

5

0,0313

0

0,04

1 1 1 2 2 2 2 1+2

The calculation schemes with boundary conditions and results are shown in the Fig. 97 and Fig. 98. Thereby the worst case scenario is assumed: the exterior sliding glass system is opened so exposing the inner window to the exterior environmental conditions. The critical isotherm of the +12,6°C temperature is marked in red. It is seen, that in both installation variants the junction between window frame and glazing has the lowest surface temperature. While for the windows with higher thermal quality this does not constitute a critical problem, in case of lower window thermal quality, the temperature at this point does not even reach the minimal +12,6°C, thus making mold formation possible. However, the results must be critically accessed, because the detail level of the performed simulation may be not enough for accurate temperature identification.

For the more detailed investigation the real frame structure would be needed. Regarding both investigated aspects the first installation alternative is more rational. Moreover, this is also the simpler installation method.

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Fig. 97 Isotherms and thermal bridges for the first window installation variant (without exterior glazing)

Fig. 98 Isotherms and thermal bridges for the first window installation variant (without exterior glazing) 101

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3.3.3.4.2 Thermal properties

V1 – no air inlet (windows WK, WB)

V1 – no air inlet (windows WK, WB)

Qgap(t) – energy used to raise the air temperature in the gap from θe to θgap during the time period t Qw1(t) – total heat losses through the exterior glazing during the time period t, Wh Qw2(t) – total heat losses through the inner window during the time period t, Wh Aw1 – total area of the exterior glazing, m² Aw2 – total area oft the inner window, m² Ag2 – total glazing area of the inner window, m² g1 – solar energy transmittance coefficient for the exterior glazing, g2 – solar energy transmittance coefficient for the inner window glazing, Qs – solar energy during the time period t, Wh Is – solar energy flow, W c – specific heat capacity of the air Wh/(kgK) V – air volume of the cavity, m³ ρ – air density, kg/m³ θi - interior air temperature, °C θe – exterior air temperature, °C θgap – gap air temperature, °C

Fig. 99 Energy balance of the double windows The energy balance of the double window is illustrated by energy flow charts Fig. 99. The exterior glazing captures part of the heat transmission losses from the existing windows as well as the reflected part of solar gains. This energy is in turn used for warming-up the air in the cavity. This brings two benefits:

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-

The heat transmission losses through the windows Qw2 are reduced, because air temperature in the gap is higher than outdoors. The temperature reduction factor Tf is calculated using the equation

It expresses the reduction of the transmission losses due to the higher temperature zone in reference to the outdoors conditions.

-

The pre-warmed gap air can be supplied into the interior space by an automatically controlled air-inlet, which is mounted on the window head, so reducing ventilation heat losses. The heat recovery efficiency of the common mechanical ventilation systems is defined through the heat recovery rate , which shows, how much the exhaust air pre-warms the supply air. Although in the analyzed system the energy source for the supply air pre-warming is different, for the comparison purposes the same factor  is used. It equals 1-Tf. As only the windows in the living and sleeping rooms have the air inlets, the  values are calculated only for these windows. The whole ventilation system is discussed in the chapter 3.3.4.1

Fig. 100 Different air flow and temperatures distribution in the double window cavity: without air inlet (left) and with air inlet (right) The final gap air temperature depends on the inflow of the cold exterior air. This value is different for the window with and without air inlets. In order to simplify the calculations, uniform spatial temperature distribution in the cavity is assumed. This means, that the air flows constantly into and out of the cavity through the whole window area. In case of closed inner window, this approximation is close to the reality, because the exterior glazing has vertical and horizontal slots between the panes so enabling relative even mixture of the air flows. According to the study of DALER (68), a vertical 70x1,5 cm (0,01 m²) slot enables a 7,0 m³/h air flow on 14 K temperature difference. The same, but horizontal slot provides a 1,5 m³/h air flow. The gap between the panes in the analyzed glazing system is three times narrower (0,5 cm). Assuming a linear relation between the width of the opening and the air flow, the used slide glass system allows a 3,3 m³/h 103

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and 0,7 m³/h air flow per 1 m vertical and horizontal gap between the panes, respectively. Thereby a high reserve is assumed, because a 14 K temperature difference between the cavity and outdoors is not likely to be achieved. If the air inlet is installed on the top of the window and a sufficient suction for the right air flow direction is provided, the air temperature distribution becomes inconstant. For accurate identification of the spatial temperature distribution and eventual additional energy losses through convection, a comprehensive CFD analysis is needed. However in the study it is assumed, that this inconstant spatial temperature distribution does not affect average temperature value, which is calculated using the same equation as for the window without air inlet.

The gap air temperature for the every hour in the year is calculated using the following equation: (

)

(

(

)

(

)

(

(

))

)

The values for the exterior air temperatures and the solar radiation are based on the hourly data.

Moreover, the solar radiation values are calculated considering the hourly shading by the built environment for the particular window. The shading obstacle parameters are already defined in the chapter 2.4.1.1. All north oriented windows are fully shaded during the heating season and the energy losses through the inner window are the single source for the pre-warming of the cavity air. Therefore, the temperature reduction factor for these windows remains constant. For the south oriented windows the over the year changing solar gains make a very high influence on the resulting temperature reduction factor, as shown in the Fig. 101.

6

001

4

001

2

Tf,av = 0,65

001

001

0

000

-2

000

-4

000

-6

000 000

-8 Oct

Nov

Dec

Jan

Feb

Mar

Apr

001 Temperature reduction factor Tf, -

8

Tf,av,WQ = 0,69

001

Temperature outdoors,° C

Temperature reduction factor Tf, -

001

With air inlet - WR Tf,av,WQ = 0,75

001

6

001

4

001

Tf,av = 0,72

001

2

001

0

000

-2

000

-4

000

-6

000 000

-8 Oct

Nov

Dec

Jan

Feb

Mar

Apr

South

South+WQ

South

South+WQ

North

North+WQ

North

North+WQ

Temperature outdoors

8 Temperature outdoors,° C

Without air inlet - WK

Temperature outdoors

Fig. 101 Average monthly temperature reduction factors during the heating season for the south and north oriented 1,45x1,55 m windows in the 2nd storey, regarding their thermal quality: without air inlet (air flow 11,5 m³/h), with air inlet (air flow 24,0 m²/h)

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For the comparison purposes the temperature reduction factor Tf was additionally calculated using the software Therm 7.3. This time the normal conditions are assumed, whereby the exterior glass sliding system is fully closed and the buffer zone in the gap is formed. The simulation is performed only for the better window installation variant. It is assumed that the inflow of the cold exterior air into the cavity is minimal. For this, in the program Therm 7.3 the air gap material is defined as Frame cavity slightly ventilated NFRC 100. This cavity model is based on ISO 15099 and is originally intended for ventilated window frame cavities of max 3 mm dimensions. Therefore the Therm simulation results should be accessed with caution. These are shown in the Fig. 102. The temperature reduction factor according to the Therm simulation (0,66) is slightly lower than according to the static calculations (0,73). This proves that the applied static calculation method provides a sufficient reserve and can be treated as reliable.

Fig. 102 Therm temperature simulation of the exterior wall and window junction

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3.3.3.4.3 Detail

Fig. 103 Principal scheme of window installation As the mentioned in the chapter 3.2.4, the window elements are a special type of façade panels, which allows adjustment of the prefabricated elements on the existing façade. Their boundaries are defined by the biggest window, which can be inserted into the particular place. If a smaller window must be installed, the remaining part of the window element is filled with the exterior wall construction. In this way, the window elements can be simply replaced with each other, as shown in the Fig. 103. The geometry based module W is the key factor for their structure, because it provides sufficient information about all the components except the inner window. Thus, the inner window of a certain size (module W) and thermal quality (module WQ) can be installed into the already prefabricated structure later.

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Fig. 104 Detail window element W1 A detail section of the connection between the window element, façade panel and the existing structure is shown in the Fig. 104. Thereby the colors have the same meaning as in the previous details: red – prefabricated façade panel; green – on-site installation; black – existing structure; blue – prefabricated window element. One must be able to change the window elements one-byone. Therefore, an easily dismountable connection must be developed. In the proposed solution the variable gap between the window element and the TES-panel is filled with mineral wool, sealed with a wind-barrier membrane and then covered with a split metal sheet frame, which adapts to the actual gap size and still provides a sufficient water protection. In this way, the rendering works around the window opening are avoided. The window element can be fixed to the façade panel by using special adjusting screws (Justierschrauben), which allow setting the window element to the exact vertical position without a need of additional adjusting underlay at the base. All the membranes are already fixed to their host elements on one side, while the other side must be fixed to the structure on site, so forming a continual vapor barrier on the interior wall surfaces and a reliable air-tightness layer on the exterior side. Around the window opening a stripe of mineral wool 107

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is inserted in order to prevent fire distribution between the different rooms through the adaption layer. The step-by-step mounting process is shown in the Fig. 105.

1.

2.

3.

Fig. 105 Mounting process of the window element, based on the module W1

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3.3.3.4.4 Retrofit modules WQ and W for separate windows - overview Kitchen window WK

Fig. 106 Retrofit variants of the kitchen window: WK1 and WK2 Table 27 Thermal properties of the kitchen window WK1 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,33 1,28 1,22 1,19 1,18 1,22

Tf, 0,71 0,68 0,65 0,64 0,63 0,65

North U w, W/(m²K) 1,47 1,47 1,47 1,47 1,47 1,47

Tf, 0,79 0,79 0,79 0,79 0,79 0,79

WQ2 South U w, W/(m²K) 0,99 0,95 0,90 0,87 0,87 0,90

Tf, 0,76 0,72 0,69 0,67 0,66 0,69

North U w, W/(m²K) 1,10 1,10 1,10 1,10 1,10 1,10

Tf, 0,84 0,84 0,84 0,84 0,84 0,84

Table 28 Thermal properties of the kitchen window WK2 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,32 1,26 1,21 1,18 1,17 1,21

Tf, 0,72 0,69 0,66 0,64 0,64 0,66

North U w, W/(m²K) 1,45 1,45 1,45 1,45 1,45 1,45

Tf, 0,79 0,79 0,79 0,79 0,79 0,79

WQ2 South U w, W/(m²K) 0,98 0,93 0,89 0,86 0,86 0,89

Tf, 0,76 0,73 0,69 0,67 0,67 0,69

North U w, W/(m²K) 1,08 1,08 1,08 1,08 1,08 1,08

Tf, 0,84 0,84 0,84 0,84 0,84 0,84 109

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Living room window WL

Fig. 107 Retrofit variants of the living room window: WL1 and WL2 Table 29 Thermal properties of the kitchen window WL1 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,38 1,32 1,27 1,24 1,23 1,27

Tf, 0,73 0,71 0,68 0,66 0,66 0,68

North U w, W/(m²K) 1,50 1,50 1,50 1,50 1,50 1,50

Tf, 0,80 0,80 0,80 0,80 0,80 0,80

WQ2 South U w, W/(m²K) 1,02 0,97 0,93 0,91 0,90 0,93

Tf, 0,78 0,74 0,71 0,69 0,69 0,71

North U w, W/(m²K) 1,11 1,11 1,11 1,11 1,11 1,11

Tf, 0,85 0,85 0,85 0,85 0,85 0,85

Table 30 Thermal properties of the kitchen window WL2 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,35 1,29 1,24 1,20 1,20 1,24

Tf, 0,71 0,68 0,65 0,64 0,63 0,65

North U w, W/(m²K) 1,49 1,49 1,49 1,49 1,49 1,49

Tf, 0,79 0,79 0,79 0,79 0,79 0,79

WQ2 South U w, W/(m²K) 1,00 0,95 0,91 0,88 0,87 0,91

Tf, 0,76 0,72 0,69 0,67 0,66 0,69

North U w, W/(m²K) 1,11 1,11 1,11 1,11 1,11 1,11

Tf, 0,84 0,84 0,84 0,84 0,84 0,84

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Bedroom window WR

Fig. 108 Retrofit variants of the bedroom window: WR1 and WR2 Table 31 Thermal properties of the bedroom window WR1 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,43 1,39 1,34 1,31 1,31 1,34

Tf, 0,77 0,74 0,72 0,70 0,70 0,72

North U w, W/(m²K) 1,54 1,54 1,54 1,54 1,54 1,54

Tf, 0,83 0,83 0,83 0,83 0,83 0,83

WQ2 South U w, W/(m²K) 1,05 1,02 0,98 0,96 0,95 0,98

Tf, 0,80 0,78 0,75 0,73 0,73 0,75

North U w, W/(m²K) 1,14 1,14 1,14 1,14 1,14 1,14

Tf, 0,87 0,87 0,87 0,87 0,87 0,87

Table 32 Thermal properties of the bedroom window WR2 Floor

1 2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,37 1,32 1,27 1,24 1,24 1,27

Tf, 0,75 0,72 0,69 0,68 0,68 0,69

North U w, W/(m²K) 1,48 1,48 1,48 1,48 1,48 1,48

Tf, 0,81 0,81 0,81 0,81 0,81 0,81

WQ2 South U w, W/(m²K) 1,01 0,97 0,93 0,91 0,90 0,93

Tf, 0,79 0,76 0,73 0,71 0,70 0,73

North U w, W/(m²K) 1,10 1,10 1,10 1,10 1,10 1,10

Tf, 0,86 0,86 0,86 0,86 0,86 0,86

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Balcony door WB

Fig. 109 Retrofit variants of the balcony door: regular floor - WB1; ground floor - WBG1 and WBG2 Table 33 Thermal properties of the balcony door WB1 Floor

2 3 4 5 Average

WQ1 South U w, W/(m²K) 1,27 1,16 1,09 1,08 1,16

Tf, 0,65 0,60 0,56 0,56 0,60

North U w, W/(m²K) 1,64 1,64 1,64 1,64 1,64

Tf, 0,85 0,85 0,85 0,85 0,85

WQ2 South U w, W/(m²K) 0,93 0,85 0,80 0,78 0,85

Tf, 0,68 0,62 0,58 0,57 0,62

North U w, W/(m²K) 1,21 1,21 1,21 1,21 1,21

Tf, 0,89 0,89 0,89 0,89 0,89

Table 34 Thermal properties of the balcony door WBG1 and WBG2 Floor

1

WQ1 South U w, W/(m²K) 1,38

Tf, 0,71

North U w, W/(m²K) 1,66

Tf, 0,86

WQ2 South U w, W/(m²K) 1,04

Tf, 0,74

North U w, W/(m²K) 1,26

Tf, 0,89

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3.3.4

Building systems

3.3.4.1 Ventilation 3.3.4.1.1 Retrofit module V1: Mechanical demand controlled exhaust air ventilation system

Fig. 110 Ventilation system scheme V1 The basic ventilation version is shown in the Fig. 110. The decentralized system is combined with the proposed double windows and its installation is minimally invasive. Fresh outdoor air is prewarmed in the cavity of the double window and then supplied into the room through a humidity sensible air inlet, which is mounted on the top of the inner window frame. The exhaust air leaves the room through demand controlled air outlets, which are installed in the bathroom and kitchen and lead the exhaust air into the existing vertical ventilation shafts. The shafts are thoroughly cleaned and an exhaust air ventilator is mounted on the top of the installation block, covering 10 ventilation shaft openings at once. The ventilator generates a constant suction and thus works in tune with the demand controlled air outlets and humidity sensible air inlets, ensuring a right air flow direction.

Fig. 111 Energy balance The proposed system saves the energy in two ways. Firstly, the demand controlled ventilation system enables to minimize the ventilation air flow and thus reduce the heat losses through ventilation. For such system an average controlled air-exchange ratio n of 0,35 h-1 can be applied in the calculations (69). Secondly, the supply air is pre-warmed in the double window cavity, and 113

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this is represented by the “artificial” heat recovery ratio μ, as discussed in the chapter 3.3.3.4.2.

The heat recovery ratio was calculated on hourly basis for the whole heating season using the equation

Thereby the same climate dataset for Kaunas like in the chapter 3.3.3.4.2 is used. The gap air temperatures were also calculated in this chapter. The passive house standard requires 30 m³ of fresh air per person hourly. According to the standard EN13779 such airflow ensures a moderate indoor air quality (CO2 content 600-1000 ppm), which complies with the Lithuanian hygiene norms (maximal CO2 content in living space – 1000 ppm). As the number of the supply windows equals the number of the residents, the 30 m³/h is set as a constant supply air flow for a single window.

This is higher than the annual average flow of 22,4 m³/h per person, but lower than the occurring maximum of 60 m³/h. However, the maximal air flow is required only about an hour or two daily (during the cooking or showering), while the ventilation during the day time, when nobody is in the apartment is almost switched off. The basic ventilation of 30 m³/h per person is present during the night time, when the heat recovery rate cannot be improved by the solar gains. Therefore, the selections of the later value as a constant air flow for the calculations of the heat recovery rate ensures a sufficient reserve. The simulation results are shown in the Fig. 112, Fig. 113 and Fig. 114. Thereby, a high influence of the solar gains is visible. The supply air temperature in October and April is very close to the indoor air temperature, which ensures a sufficient thermal comfort.

However, the supply air temperatures during the winter nights are relative low and draughts may occur. To prevent this, the supply air must be sufficiently heated till it reaches the users. Therefore, a grid on the window sill must be installed, so that the warm air from the radiators under the sill could unrestricted rise vertically and mix with the cold supply air as soon as possible. If it is still insufficient, the supply air flow could be manually limited, which however results in poorer air quality.

20

160

Temperature, °C

120 100

10

80

05

60 40

00

Solar radiation, W/m²

140 15

Solar radiation, vertical Temperature exterior Temperature supply

20 -05

00 10

11

12

1

2

3

4

Months

Fig. 112 Average monthly exterior and supply air temperatures during the heating season, window WL1, south, 3rd floor

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100% Heat recovery rate µ, %

90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 6 11 16 21 26 31 5 10 15 20 25 30 5 10 15 20 25 30 4 9 14 19 24 29 3 8 13 18 23 28 5 10 15 20 25 30 4 9 14 19 24 29 10

11

12

1

2

3

4

Heat recovery rate µ, %

Fig. 113 Average daily ventilation heat recovery rates during the heating season, window WL1, south, 3rd floor 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Oct

Nov Dec Jan Feb Mar Apr 1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours

Fig. 114 Average hourly ventilation heat recovery rates for separate months, window WL1, south, 3rd floor The proposed humidity sensitive air inlets are based on the technology, patented by the French company AERECO. The work of the inlets does not need electricity, as the humidity sensitive parts change their dimensions according to the relative indoor air humidity and so regulate the opening size together with the supply air flow. The dependency of the supply air flow rate on the relative indoor air humidity and pressure difference between indoors and outdoors for the selected AERECO product ZHF 40 (Fig. 115) is shown in the Fig. 116.

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Fig. 115 Humidity sensible air inlet AERECO ZFH 40: 3D view and projections (69) 40 Supply air flow, m³/h

35

30

10 Pa

25

8 Pa

20

7 Pa

15

5 Pa

10

4 Pa

5

2 Pa

0

0

10

20

30

40

50

60

70

80

90

100

Relative humidity indoors, %

Fig. 116 Relation between supply air flow, relative humidity and pressure differences (69) Important feature of these air supply units is that they can be easily mounted on the existing windows. For this, firstly the horizontal slots are cut on the top of the plastic window frame. Then, the humidity sensible air inlet is attached on the interior side of the window frame, while a canopy for weather and insect protection is mounted on the exterior side. According to the manufacturer‟s recommendations, the cutting works should be performed on the dismantled window. This fits perfectly to the proposed concept of the existing windows reuse, because they must be anyway removed from their original location and then again installed into the new window elements in the factory. This means, the air inlets can be also mounted in the factory.

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Front view

Cutout

Fig. 117 A detail drawing of on a plastic window installed humidity sensible air inlet AERECO ZFH 40 with canopy WHI 05 on the exterior side (69) 3.3.4.1.2 Retrofit module V2: Mechanical ventilation with exhaust air heat-pump

Fig. 118 Mechanical exhaust air ventilation system with heat recovery through EAHP Typical problems of installation of common mechanical ventilation system with heat recovery in the existing buildings could be avoided by mounting the ventilation ducts into the vertical TES-panels and using the existing ventilation shafts for the exhaust air. However, the ventilation ducts must be installed into the façade panels already in the factory. Moreover, the suggested elements of the module V1 become redundant, as they cannot be combined with the new ventilation system.

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These factors make the common mechanical ventilation system with heat recovery not compliable with the proposed “step-by-step retrofit” strategy.

Therefore, the suggested advanced solution for ventilation is based on an exhaust air heat pump (EAHP). The company AERECO has conceptualized this system as a modular extension for their demand controlled ventilation system. The EAHP is split: the heat from the exhaust air is transferred into the fluid medium by the separate heat exchanger. It joins the existing exhaust air ventilator on the roof and together they form the outdoor part of the heat pump. The medium (in this product – R290 propane) is then transported into the indoor part of the heat pump, which is placed in the technic room in the basement. The EAHP produces 60° C water, which can be used for heating as well as for domestic hot water. In this way the EAHP connects all three types of building systems (ventilation, space heating and DHW). Therefore, its effect can be assessed only considering all these systems.

Fig. 119 Energy balance in winter: EAHP supports heating system

Fig. 120 Energy balance in summer: EAHP generates heat for DHW system Heat pump allows extracting any energy amount from the exhaust air - the total EAHP heat output depends on the capacity of the device and can theoretically cover the whole heat demand.

However, the EAHP has a stable energy source, because the exhaust air has a constant temperature and the flow (20° C and 1680 m³/h, respectively). Therefore, the more energy from the exhaust air is extracted, the lower the temperatures of the outgoing air and the incoming medium are, and this requires more electricity. As a result, the COP-value of the EAHP falls, while the total 118

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heat capacity increases. This dependency is shown in the Fig. 121, where the black dots represent the declared values of the certain products and the green dots show the assumed COP values for the range of capacities. The used values are lower than declared ones, because of possible losses through inconstant operation. As the price and primary energy content of the electricity is higher than of the available district heat, an operation of a too powerful EAHP system with low average COP-value may be even more expensive and energy-inefficient than the district heating system.

Long term parameter measurements of EAHP system in combination with district heating in Nordic climate conditions (70) reveal, that an average annual COP-values of 3,0 to 3,3 can be achieved.

Then the possible savings for heating and DHW per kWh of EAHP heat output are: -

21-28% primary energy (electricity 2,8, district heating 1,3 (21))

-

26-33% costs (electricity 0,129 EUR/kWh (23), district heating 0,0558 EUR/kWh (53)) 005 004

COP

004

y = -0,0717x + 4,1995

003 003 002 002 4

6

8

10

12

14

16

18

20

22

24

26

28

30

Total heat cacapity of the EAHP, kW

Declared values A20/W60

applied values A20/W60

Fig. 121 Correlation between the COP-values and EAHP heat capacity (exhaust air flow 1680 m³/h) The Fig. 121 suggests that a cost and energy efficient operation can be expected using heat pumps with lower than 14 kW capacities. In order to calculate, how much of the heat demand is covered with the EAHP, the monthly heat demand values are combined with the monthly EAHP heat production values (see Fig. 122). A monthly-based calculation is necessary because in case of more powerful heat pumps, the operation periods in part-load are present.

119

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16 14

kWh/m²

12 10 8 6 4 2 0 Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Space heating demand incl. distribution

DHW demand incl. distribution

EAHP capacity 6 kW

EAHP capacity 11 kW

EAHP capacity 17 kW

EAHP capacity 23 kW

Nov

Dec

Fig. 122 Monthly heat demand (incl. distribution losses) of the basic retrofit package and the total heat outputs from the EAHP of various capacities The final district heating and EAHP electricity demands are estimated by separating monthly heat production values and multiplying them by the device-specific heat generation factors. In case of district heating it is 1,04. For the EAHP electricity it equals 1/COP. The resulting monthly final energy demand values regarding different EAHP capacities are shown in the Fig. 123. As the kWh price of electricity and the district heat is known, operation costs are calculated. The total primary energy demand for all variants is estimated as well.

Final energy output, kWh/(m²a)

14 12 10 8 6 4 2 0 Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

6 kW district heat

6 kW electricity

11 kW district heat

11 kW electricity

17 kW district heat

17 kW electricity

23 kW district heat

23 kW electricity

Nov

Dec

Fig. 123 Monthly electricity and district heat demand for various EAHP capacities The aim of the optimization is to achieve maximal primary energy savings in combination with a reasonable payback period of the EAHP. Current market prices of the air-water heat pumps range from 600 to 1500 EUR per 1 kW capacity. The conservative price assumption for the calculations of the payback period is 2000 EUR/kW, including costs for installation and the required 120

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20%

25

18% 16%

20

14% 12%

15

10% 08%

10

06% 04%

05

Payback period, years

PE savings in reference to package 1, %

accessories. The results are shown in the Fig. 124. Regarding the PE-efficiency, the EAHP capacities between 10 and 15 kW are optimal. Heat pumps with lower than 15 kW capacity have a decent payback period of less than 15 years. An optimal solution is a 11 kW EAHP with a COPvalue of 3,11. However, it must be noted, that in case of different primary energy factors and energy prices, other size of the EAHP can be optimal.

02% 00%

00 4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

EAHP capacity PE Savings for space heating and DHW

Payback period

Fig. 124 Search for the optimal EAHP capacity regarding the cost- and energy efficiency (in reference to the retrofit package 1) As the EAHP system is conceptualized for the ventilation heat recovery, the produced heat is firstly used for the space heating. If the EAHP heat output is higher than the space heating demand, the remaining heat is used for DHW. Heat from the district heating system covers the remaining heat demand.

121

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Final energy demand, kWh/m²

16 14 12 10 8 6 4 2 0 1

2

3

4

5

District heat, heating

6

7

8

9

10

11

12

EAHP for heating, electricity

EAHP for heating, recovered ventilation losses District heat, dhw EAHP for DHW, electricity

EAHP for DHW, air energy

Fig. 125 Monthly final heat energy demand regarding different energy sources and purposes As the suggested EAHP system is currently not available in the used energy calculation software PHPP. From the Fig. 125 obtained information is used for an appropriate translation of the system into the software: -

-

EAHP heat output for the space heating: o

Used electricity is defined as a direct electrical heating. Its share in the total heat demand (excluding recovered ventilation losses) is 28%.

o

The rest part of the heat is the recovered part of the ventilation heat losses, which is defined through the ventilation heat recovery rate v2, which equals 67 %. The total ventilation heat recovery rate v is the sum of the v2 and v1 and range between 87% and 92%.

EAHP output for the DHW: o

An additional energy generation source is created. The generation factor is 32,1% (1/COP). This device covers 52% of the DHW demand. The rest is covered by the district heat.

3.3.4.2 Heating H New two-pipes heating system with individual temperature control and accounting is installed. The heat distribution pipes are mounted into the prefab façade elements (Fig. 126), thus providing a sufficient thermal insulation of the pipes and preventing vertical noise distribution through them. As a thick wall insulation covers the pipes on one side, it is assumed that, they are installed indoors.

Because timber panels can be moved in further retrofit phases, easy detachability and addition of 122

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

heating system components must be ensured, in order to adapt to the changing room geometry.

Therefore, each room has a separate vertical heat distribution branch. The vertical branches connect to the horizontal collector/distributor pipes through a single detachable connection at the base. Basically, the existing radiators can be regulated for the new system and used further.

However, they cannot be used together with the module W2 (higher windows), because they are too high and would clash with the window sill. For the bigger windows special lower radiators need to be installed. New insulated heat distribution pipes are also mounted on the basement ceiling.

The DHW-pipes are insulated. The towel dryers are disconnected from the DHW circulation system and new individually controlled radiators are installed in order to ensure the required temperature in the bathroom. For this, 6 separate vertical heating pipe branches are mounted in the existing shafts. Alternatively, electric towel dryers can be used. On the one side this would reduce the construction works inside the apartments. On the other side, the direct use of electricity for the heating purposes is more expensive and increases primary energy demand and CO2 emissions of the building.

Table 35 Retrofitted heating and DHW distribution pipes Pipe type

Within thermal envelope (20 °C) Length Insulation, W/(mK)

In the basement (7,7 °C) Length Insulation, W/(mK)

Heating distribution pipes

462,4

0,15

151,3

0,15

DHW pipes

192

0,15

78,4

0,15

Fig. 126 Heat pipes distribution scheme on the south façade 3.3.5

Preliminary price estimation

The prices of all the retrofit measures are summarized in the Table 36. In most cases, they are basing on the prices, stated in the approved investment plan of the same type building retrofit. The assumptions for the deconstruction and excavation works base on very rough internet researches.

Ventilation element prices are taken from the Lithuanian reseller‟s website. The amounts are 123

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calculated for the basic retrofit package. It is seen, that the construction works could cost about 200 EUR/m² (basing on the initial apartment floor area of 1571,9 m²), while the total costs are about 210 EUR/m². A typical C-class retrofit of the same building would totally cost about 155 EUR/m². For the further calculations of the payback periods, a total basic retrofit package price of 250 EUR/m² is assumed, so that a sufficient reserve is ensured.

Table 36 Total construction works price estimation (basic retrofit package) Building element/field

Construction works, units

Amount, basic retrofit

Assummed price, EUR/unit

Total price, EUR

Exterior wall

TES and facade cleaning, m²

1217,20

90

109548

Price EUR/m² floor area 69,69

Exterior wall

Concrete cut and dismantlement, m

1056,74

10,0

10567

6,72

Exterior wall

Base isolation, m²

112,32

80

8985,6

5,72

Roof

Isolation, m²

450,08

71,0

31963

11,00

Roof

Deconstruction concrete, m³

152,00

30

4560

22,22

Bacement ceiling Bacement ceiling Ground works

Slab isolation, m²

368,66

52,2

19236

20,33

Thermal bridge removal, m²

59,49

52,2

3104

2,90

Moved fill, m³

458,37

15,0

6876

12,24

Windows

New windows, m²

96,21

179,7

17288

1,97

Windows

Addition of exterior glazing, m²

349,23

100

34923

9,62

Ventilation

Installation of air inlets/outlets, units

130,00

70

9100

1,28

Ventilation

Cleaning shafts, apartments

30,00

143,8

4313

8,63

Ventilation

Exhaust air ventilators

6,00

1200,0

7200

3,31

Heating systems Heating systems Heating systems Heating systems DHW

Replacement of pipes, m

613,68

24,6

15121

4,25

Isolation of distribution pipes in the basement, m valves and individual accounting devices, unit Radiators - new installation, units

151,28

13,3

2017

5,79

208,00

65,2

13566

2,74

104,00

50,0

5200

4,58

Replacement and isolation of pipes, m

240,36

27,8

6687

4,37

310255

197,38

Total

Table 37 Final retrofit price estimation (basic retrofit package) Total price, EUR

Construction works

Price, EUR/m² floor area 197,38

Design, 2% of total

4,06

6385

Construction supervision Administration

2,78

4363

2,94

4617

Total

207,17 (assumed 250)

325620 (assumed 392938

310255

124

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3.4

Retrofit configurator – results

3.4.1

Configuration

Different retrofit module packages were evaluated. Thereby the principle of the retrofit configurator was tested by using the already discussed PHPP program. As it is an Excel-based tool, the whole configuration process is also created in Excel. It is illustrated in the Fig. 127 and consists of the following steps: 1. Defining retrofit module combination. A basic table with the variable module names, codes and applied versions is created. The basic version is marked as „1.‟, while the advanced is named „2.‟. The numbers of the versions are entered manually and represent the wishes of the residents.

2. Formation of the variable data input for calculations. Each retrofit module consists of few parameters. They have different values for the basic (1.) and advanced versions (2.). All these values are listed in the second table. Depending on which version of a particular module is entered in the first table, the respective parameter values are selected and listed in the column „applied values‟. A summary of all the parameter values can be found in the table in the back overlap sheet.

3. Calculation. The values from the „applied values‟ column are linked to the required cells in the PHPP spreadsheets and the calculations are automatically performed for any retrofit module combination. The same climate data set as in the chapter 2.4.4.3 was used. The fixed retrofit measures, defined in the chapters 3.3.3.1, 3.3.3.2, 3.3.3.3, and 3.3.4.2 remain the same.

4. Results. The results table is linked to the respective cells in the PHPP spreadsheet. The received and the derived results are listed in the Table 38. The results are visualized in the diagrams. Due to the change of the retrofit module version in the basic table, the values in the results table are automatically updated together with the diagrams. Thus, the consequences of the manually formed retrofit module combination are presented to the end-user.

As discussed in the chapter 2.4.4.3, the TFA is a reference for the space heating energy demand value (EnerPHit-threshold – max 25 kWh/m²) and the other components of the useful energy balance like transmission losses. All the other values refer to the AFA, as this area is relevant for the end-users, therefore the total values were taken from the PHPP. For the energy calculations on the apartment level, only the useful energy balance values are separately calculated with PHPP. The distribution and generation losses are evenly distributed among the condominiums, depending on their floor area. As the average electricity consumption for the household equipment of about 40 kWh/(m²a) (Fig. 36) almost equals the EnerPHit-threshold for the total primary energy demand (120 kWh/m²), this threshold is not likely to be achieved anyway. Thus the energy for the household equipment is not included in the primary energy demand and its value refers to AFA. 125

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Table 38 Results of the configuration ant their calculation methods Result Space heating energy demand, and the other components of the useful energy balance (Fig. 34), kWh/(m²a) Final energy demand for heating, district heat (Fig. 119), kWh/(m²a) Final energy demand for DHW (incl. circulation), district heat (Fig. 120), kWh/(m²a) Final energy demand for heating, electricity (Fig. 119), kWh/(m²a) Final energy demand for DHW (incl. circulation), electricity (Fig. 120), kWh/(m²a) Final energy demand for ventilation, electricity, kWh/(m²a) Primary not renewable energy demand for heating, DHW and ventilation, kWh/(m²a) Total primary energy savings, % CO2 emissions due to heating, DHW and ventilation, kWh/(m²a) kgCO2-eq/(m²a) Total savings of the CO2 emissions, % Operation costs for DHW, heating and ventilation, EUR/(m²a) Total operation costs savings, % Payback period (incl. annual 3% energy price increase), years Long-term prevention of the fuel poverty for households with single and two pensioners Retrofit package recommendations for the residents according to their age group (Table 10)

Refere nce TFA

Calculation method

AFA

Total value output from PHPP, kWh/a

AFA

Total value output from PHPP, kWh/a

AFA

Total value output from PHPP, kWh/a

AFA

Total value output from PHPP, kWh/a

AFA

Total value output from PHPP, kWh/a

AFA

Final energy values multiplied by: fPR,n – not renewable primary energy conversion factor fPR,n,district heat = 1,30 (21) fPR,n,electricity = 2,80 (21) Reference: Initial value of 275 kWh/(m²a) (chapter 2.4.4.3.3), multiplied by the AFA before retrofit Final energy values multiplied by: MCO2 – not renewable primary energy conversion factor MCO2, district heat = 0,29 kgCO2-eq/kWh (21) MCO2, electricity = 0,60 kgCO2-eq/kWh (21) Reference: Initial value of 61,4 kgCO2-eq/(m²a) (chapter 2.4.4.3.3), multiplied by the AFA before retrofit Final energy values multiplied by: District heat price = 0,0558 EUR/kWh (53) Electricity price = 0,129 EUR/kWh (23) Reference: Initial value of 11,82 EUR/m² (see chapter 2.4.4.3.3), multiplied by the AFA before retrofit Assumed basic retrofit price 250 EUR/m² (chapter 3.3.5), multiplied by the AFA before retrofit. The assumed prices of the other advanced retrofit modules are found in the table in the back overlap sheet.

Annual increase of 3% and 4% (based on chapter 2.3) Income development from the chapter 2.4.5.

Initial incomes of a single pensioner (year 2015) – 2963 EUR/a (45)

Total value AFA

Total value AFA Total value Total value Total value -

Output from PHPP

Subjective author‟s recommendation, considering the assumed priorities of the age groups (Table 10) and the long-term prevention of fuel poverty. Made only on the apartment level.

126

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3. Energy analysis

Key-results

1. Definition of retrofit module comnbination

2. Formation of data input Excel-based Retrofit Configurator

End-user

4. Results and recommendations

Fig. 127 Applied retrofit configuration process Various effects of many different module combinations (packages) must be presented and therefore an identification system for the diverse possible combinations is used. For this, each retrofit module has a unique code. In order to simplify the representation, the combination of all the modules with the basic parameter values has a code 1. This combination represents the basic retrofit. If some advanced modules are implemented (for instance ventilation with EAHP and kitchen extension), their codes (V and K, respectively) are added to the basic code 1 and form an individual code for the resulting retrofit package (1+V+K). In this study totally 18 variants of retrofit packages are compared. These are divided into three groups, according to the TFA of the package. For each area-based group 6 possible combinations of the advanced energy efficiency modules are assigned. These modules are ventilation V, windows quality WQ and bigger south windows Ws. The latter is regarded as an energy efficiency measure because of higher solar gains. The comparison is done for the whole building and few separate apartments. Thereby, the same configuration method was used.

127

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3.4.2

Building level

Table 39 Main geometric data of the analyzed retrofit packages on the building level Existing

1

AEW2 = 283,9 m² Aw,S = 195,9 m² 1+Ws

TFA = 1620,2 m² AFA = 1571,9 m² A/V = 0,38

1+K

AEW2 = 534,7 m² Aw,S = 195,9 m² 1+K+Ws

1+K+L

AEW2 = 578,6 m² Aw,S = 195,9 m² 1+K+L+Ws

AEW2 = 231,2 m² Aw,S = 248,6 m²

AEW2 = 482,0 m² Aw,S = 248,6m²

AEW2 = 525,9 m² Aw,S = 248,6m²

AEW1 = 933,3 m² Aw,N = 153,4 m² AR = 450,1 m² ABC = 450,1 m²

AEW1 = 882,0 m² Aw,N = 153,4 m² Aw,W = 17,2 m² Aw,E = 34,4 m² AR = 478,9 m² ABC = 478,9 m²

AEW1 = 830,7 m² Aw,N = 153,4 m² Aw,W = 195,9 m² Aw,E = 153,4 m² AR = 507,7 m² ABC = 507,7 m²

TFA = 1789,3 m² AFA = 1732,1 m² A/V = 0,34

TFA = 1909,9 m² AFA = 1852,7 m² A/V = 0,37 75 persons

TFA = 2042,2 m² AFA = 1985,0 m² A/V = 0,35

The geometric properties of the whole building for the analyzed retrofit packages are summarized in the Table 39. The Fig. 128 shows that due the proposed retrofit measures high energy efficiency is achieved and the declared targets for state supported retrofits (40% savings for space heating) are clearly exceeded. While the basic package reduces the space heating demand by almost 3 times, the addition of advanced ventilation and better windows minimizes it to the level of the EnerPH standard (25 kWh/(m²a)). Only if all the kitchens in the building were enlarged, this standard cannot not achieved. The reason for this is slightly higher A/V ratio, compared to the packages 1 and 1+K+L. The useful energy balances for the basic and advanced retrofit package are shown the Fig. 129 and Fig. 130. As expected, the energy losses through thermal bridges, windows, and ventilation are reduced in comparison to the preliminary calculations for the C-class building (chapter 3.3.1).

128

Space heating energy demand, kWh/m²a

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Existing = 139

140 120

1

100

+WQ

80

+WQ+Ws

60 40 20

+V 51

49 44 42 29 24 23

46 41 40

45 44 32

EnerPH 28

27 26

24 23

+V+WQ

+V+WQ+Ws

0 1

1+K

1+K+L

Fig. 128 Space heating energy demand of the building for various retrofit packages Thermal bridges; 0,9

Losses

Roof; 4,3

Ventilation

120

Transmission

100

kWh/(m²a)

Windows; 28,5

140

Not useful gains

Exterior wall; 12,0

Gains Space heating energy demand Solar gains

80

0,1

60

27,5

Internal gains

50,1

40 Basement ceiling; 3,6

20 0

49,9

16,1 11,3

Fig. 129 Useful energy balance for the basic retrofit package 1 (right) and transmission losses regarding the construction type (left)

Thermal bridges; 0,9

Window s; 23,2

Exterior wall; 11,9

Roof; 4,3 Baseme nt ceiling; 3,6

Fig. 130 Useful energy balance for the advanced retrofit package 1+WQ+Ws+V (right) and transmission losses regarding the construction type (left) 129

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Final energy demand, kWh/(m²a)

Final energy demand is shown in the Fig. 131. It is divided according to the energy source and energy use. It is seen that the distribution losses in both heating and DHW systems are minimized.

The useful DHW demand for basic package is 23,4 kWh/(m²a). After the installation of the EAHP (module V) the final energy demand is considerably reduced and the electricity constitute a significant share in the final energy demand. Mechanical exhaust ventilation system requires almost negligible energy amounts.

250 200

49

Electricity, DHW Electricity, heating

100 163

Final energy demand, kWh/(m²a)

District heat, DHW

30

30

30

56

51

49

15 25

15 22

15 21

1

1+WQ

1+WQ+Ws

1+V

1+V+WQ

1+V+WQ+Ws

50 0 Existing

Final energy demand, kWh/(m²a)

Electricity, ventilation

150

District heat, heating

250

200

49

150

Electricity, ventilation Electricity, DHW

100 163

30

30

30

62

56

54

50 0

Electricity, heating

15 30

15 25

15 24

District heat, DHW District heat, heating

250 200

49

150 100

Electricity, ventilation

163

Electricity, DHW

30

50 60 0

30 54

30 53

Electricity, heating

15 28

15 24

15 23

District heat, DHW District heat, heating

Fig. 131 Final energy demand of the building regarding the energy source and energy use 130

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

In order to eliminate the influence of the different energy sources, total not renewable primary energy demand for the building operation (heating, DHW and ventilation) is accessed. The total primary energy demand falls by 57%-67% (Fig. 133). The primary energy demand ranges from 75 to 109 kWh/(m²a) (Fig. 132). Further reduction of the primary energy demand depends on the government, which could increase the share of renewables in the energy mix, so reducing its primary energy factor. As discussed in the chapter 2.3, this is already happening in the district heat sector, where biomass replaces gas. It must be noted that in case of changed primary energy factors the use of EAHP must re-accessed.

CO2 emmisions, kgCO2/(m²a)

300

Existing = 275

250 1 200

+WQ +WQ+Ws

150

+V 100

115 108 106

95

50

123 114 113 105 86

85

94

120 112 111 93

102

92

+V+WQ 91

+V+WQ+Ws

0 1

1+K

1+K+L

Fig. 132 Primary energy demand of the building for various retrofit packages 1

1+K

1+K+L

Total primary energy savings, %

0% -10% 1

-20%

+WQ

-30% -40% -50% -60%

-54%-57% -57% -62% -65%-66%

-47% -51%-52% -55% -60%-60%

-45% -48%-49% -53% -58%-58%

-70% -80%

+WQ+Ws +V +V+WQ +V+WQ+Ws

-90%

-100%

Fig. 133 Total primary energy savings of the building for various retrofit packages

131

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The other environmental indicator is the annual CO2 emissions. They are reduced by 2 to 3 times (Fig. 135), the CO2 savings are almost identical to the ones of primary energy. The floor arearelated values ranges from 24 to 16 kgCO2/(m²a) (Fig. 134). The emissions can be further reduced by increasing the share of the renewables in the energy mix.

CO2 emmisions, kgCO2/(m²a)

70

Existing = 61,4

60 1

50

+WQ 40

+WQ+Ws

30

+V 26

20

24

27

24

21

10

19

26

25

23

19

27 21

20

25

25

22

+V+WQ 20

20

+V+WQ+Ws

0 1

1+K

1+K+L

Fig. 134 Annual CO2 emissions of the building for various retrofit packages 1

1+K

1+K+L

0% -10% 1

Total CO2 savings,%

-20%

+WQ

-30% -40% -50% -60%

-54%-57% -57% -62% -66%-66%

-47% -51%-52% -56% -60%-61%

-45% -49%-49% -54% -59%-59%

-70% -80%

+WQ+Ws +V +V+WQ

+V+WQ+Ws

-90% -100%

Fig. 135 Annual total CO2 savings of the building for various retrofit packages

132

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The total costs savings almost fully correlate with the primary energy demand and CO2 emissions (Fig. 137). They range from 53% (package 1+K) to 71% (package 1+V+WQ+Ws). The initial annual costs of 11,82 EUR per square meter can be reduced to 3,25 EUR (Fig. 136).

12,00 Operation costs EUR/(m²a)

Existing = 11,82 10,00 1 8,00

+WQ +WQ+Ws

6,00 4,00

5,06 4,75

5,40 4,68 3,70

2,00

5,27 4,94

5,03 4,96 4,15

3,31 3,25

+V 4,87 3,98

3,67 3,60

+V+WQ 3,56 3,49

+V+WQ+Ws

0,00 1

1+K

1+K+L

Fig. 136 Annual operation costs of the building for various retrofit packages 1

1+K

1+K+L

0%

Total operation savings,%

-10% 1

-20%

+WQ

-30% -40% -50% -60%

-53% -58%-59% -65% -69%-70%

-46% -50%-51% -59% -63%-64%

-44% -47%-48% -57% -62%-63%

-70% -80%

+WQ+Ws +V +V+WQ +V+WQ+Ws

-90%

-100%

Fig. 137 Annual total operation costs savings of the building for various retrofit packages

133

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As the total retrofit price is very roughly estimated, the absolute values of the payback periods cannot be reliable. However, the prices for the additional measures are more accurate, so the qualitative relations between the different retrofit packages are plausible. The results are shown in the Fig. 138. As it could be expected, due to the optimization of the EAHP, the payback periods of the packages, which include the advanced ventilation module V, are clearly shorter. This means that the most energy-efficient packages also provide the highest economic benefit and it is reasonable to implement these measures sooner. The payback periods of the packages with space extension modules K and L are extended. However, the economic benefit is not the target of these modules. The gained payback periods of 17-20 years might be satisfactory, especially regarding the fact, that only slightly better payback period of 15,9 years is gained in the reality (see chapter 2.6.4). In the reality such payback period is not sufficient to repay the credit with the energy costs savings. However, regarding the very conservative assumption of retrofit price (250 EUR/m²) and the provided additional functional benefits the suggested retrofit offer clearly higher benefit. In order to get an even more economic result, either an additional state support must be provided or the investment price reduced. Both these options might be viable.

30

Payback period, years

25 23,1

20 19,5 20,3 15

20,7 17,2

18,5 18,8

25,6

24,1 24,4 20,1

20,9 21,1

26,5 26,7 1 21,7 22,4

22,7

+WQ +WQ+Ws +V

10

+V+WQ +V+WQ+Ws

05 00

1

1+K

1+K+L

Fig. 138 Average payback periods of various retrofit packages

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3.4.3

Apartment level

In previous chapter discussed results are the average results for the whole building. However, the space heating energy demand for the separate apartments varies and depends on their location, as shown in the Table 40. Due to the installed individual accounting system these differences lead to the different energy costs savings and thus different payback periods for separate apartments.

In order to identify the whole range of differences, the following 2-room apartments are analyzed: -

The average case: Apartment 2B, 4th floor (2B_4)

-

The best case: Apartment 2B, 3rd floor (2B_4)

-

The worst case: Apartment 2AE, ground floor (2AE_1)

This information is needed in order to provide the residents with fair and accurate information about the diverse possible retrofit measures.

Table 40 Space heating demand changes in separate apartments (retrofit package 1) 4

2B

2A

2A

2B

2A_E

4th Floor

-51%

-63%

-53%

-53%

-63%

-42%

3rd Floor

-66%

-78%

-66%

-66%

-78%

-52%

2nd Floor

-66%

-78%

-66%

-66%

-78%

-52%

1st Floor

-66%

-78%

-66%

-66%

-78%

-52%

Ground floor

-47%

-55%

-48%

-48%

-55%

-35%

Additionally, the most reasonable combinations of the retrofit modules for these apartments are proposed regarding the priorities of the residents of various age groups. These are summarized in the Table 10. For this purpose also the long-term prevention of the fuel poverty was assessed.

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3.4.3.1 The average case: Apartment 2B, 4th floor Table 41 Main geometrical properties of the analyzed retrofit packages: apartment 2B on 4th floor Existing

AFA = TFA = 47,23 m² A/V = 0,22

1

1+K

1+K+L

AEW2 = 7,6 m² Aw = 9,7 m²

AEW2 = 20,6 m² Aw = 11,4 m²

AEW2 = 24,7 m² Aw = 11,4 m²

1+Ws

1+K+Ws

AEW2 = 4,5 m² Aw = 12,8 m²

AEW2 = 17,5 m² Aw = 14,5 m²

AEW2 = 21,6 m² Aw = 14,5 m²

AEW1 = 11,1 m² AR = 59,38 m² AFA = TFA = 51,93 m² A/V = 0,50

AEW1 = 5,2 m² AR = 64,18 m² AFA = TFA = 55,95 m² A/V = 0,54

AEW1 = 2,2 m² AR = 68,98 m² AFA = TFA = 60,36 m² A/V = 0,52

1+K+L+Ws

All the possible geometry variants of the apartment 2B in the 4th floor are shown in the Table 43.

The space heating energy balance for the basic retrofit package (Fig. 139) shows that the transmission losses exceed the average. On the other hand, significantly more solar gains are available (27 kWh/m² compared with 16 kWh/m²), because of minimal shading through the built environment. Therefore, higher energy savings ca be achieved due to the enlargement of the south windows (module Ws) (Fig. 140). As a result, the apartment has only slightly lower space heating energy demand than the average of the building (Fig. 141). Four retrofit module combinations achieve the EnerPH-limit of 25 kWh/(m²a). The space extensions lead to higher increase in energy demand, because the relative exterior surface increase is higher than for the whole building.

136

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Losses 140

Not useful gains Ventilation

120

Transmission

100 kWh/(m²a)

Exterior walls; 6,5

Windows; 26,8 Roof; 19,7

Gains

80 60

Space heating energy demand Solar gains Internal gains

0,4 28,0

45,2

53,0

27,4

40 20

11,3

0

Fig. 139 Useful energy balance for the basic retrofit package 1 (right) and transmission losses regarding the construction type (left)

Exterior walls; 5,3

Windows; 26,0

Roof; 19,7

Fig. 140 Useful energy balance for the advanced retrofit package 1+Ws+WQ+V (right) and transmission losses regarding the construction type (left)

Space heating energy demand, kWh/m²a

140

Existing = 139

120

1

100

+WQ

80

+WQ+Ws

60

+V

40 20

48 46 42

44 42 38 25 23 21

46 44 41 31 28 26

EnerPH = 25 29 28 25

+WQ+V

+WQ+Ws+V

0

1

1+K

1+K+L

Fig. 141 Space heating energy demand of the apartment 2B on the 4th floor for various retrofit packages

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As the energy for the DHW system and the heat distribution losses do not change, the operation costs for the heating, DHW and ventilation are closer to the average values of the average of the building. They range between 4,81 and 3,13 EUR/m² (Fig. 142). The total price savings are between 51% and 66% (Fig. 143), which is very similar to the average. These also lead to similar payback periods of separate retrofit packages, as shown in the Fig. 144. Thereby the most costefficient combination remains 1+V.

Operation costs, EUR/(m2a)

12

Existing = 11,82

10

1

8

+WQ

6

+WQ+Ws

4 2

+V

4,91

4,87 3,92

3,68

3,25 3,07 2,87

4,02

4,61

3,80 3,40

3,23

3,79

3,05

3,59

3,21 3,06 2,89

+WQ+V +WQ+Ws+V

0 1

1+K

1+K+L th

Total operation costs savings, %

Fig. 142 Operation costs of the apartment 2B on the 4 floor for various retrofit packages 0% -10% -20% -30% -40% -50% -60% -70% -80% -90% -100%

1 -64%

-70%

-73%

-55% -66%

-60%

-66%

-69%

-51% -62%

-71%

-59%

-65%

-50% -61%

-68%

-69%

+WQ +WQ+Ws

-67%

+V +WQ+V +WQ+Ws+V

1

1+K

1+K+L th

Fig. 143 Total operation costs savings of the apartment 2B on the 4 floor for various retrofit packages

payback period, years

30 25 20 15 10

19,0

18,8 18,8

1

25,7

23,9

22,9

24,4

23,1

21,7

+WQ +WQ+Ws

17,9 23,1 16,4

18,0

20,4

21,7

24,6

21,9

23,0

+V

+WQ+V

05

+WQ+Ws+V

00 1

1+K

1+K+L th

Fig. 144 Payback periods of the apartment 2B on the 4 floor for various retrofit packages In order to reveal the whole economic benefit of the retrofit measures, the total apartment value was estimated. Thereby only the functional improvements were considered (space extensions K 138

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and L, balcony B and elevator E). The real estate value for the apartment is added in two ways.

Firstly, the floor area is added. Secondly, the price per square meter is increased due the key functional improvements. The later values base on the current (April, 2015) average market prices of similar 2-room apartments in in the same district. The benefits of each analyzed retrofit package are summarized in the Table 42. The gradual value increase due to the separate retrofit packages and the respective investments are illustrated in the Fig. 145. The possible improvements in a single apartment (modules W and B) increase the total apartment value by a half. Due to the space extensions the real estate value rises over 80%. Finally, after the installation of the elevator the initial value is almost doubled. It must be noted, that the generated profit (difference between the investment and the added value) is about 1,5-2,5 times higher than the investment.

Table 42 Inputs for calculation of the added value of the apartment 2B on the 4th floor Additional floor are in reference to existing, m² 4,70 m²

Square meter price EUR/m² 1280

1+B+W

4,70 m²

1340

1+B+W+K

8,72 m²

1420

1+B+W+K+L

13,13 m²

1420

1+B+W +K+L+E

13,13 m²

1480

EUR

Retrofit package 1

45000 40000 35000 30000 25000 20000 15000 10000 5000 0

84% 70% 43%

0%

49%

Functional improvements in reference to the existing conditions Improved technical quality More space for storage Improved technical quality More space for storage Exterior space (balcony and winter gardens) Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen and dining area Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen and dining area Barrier-free accessibility 91%

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Total investment, EUR Total added value, EUR Value increase in reference to the existing, %

Fig. 145 Additional value generation due to the modules for functionality: B, W, E, K and L

139

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Fig. 146 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners As seen in the Fig. 146, the threat of the fuel poverty is effectively eliminated for at least 20-25 years. Therefore, no additional energy efficiency measures are recommended to the today‟s pensioners. However, after about 35 years the basic retrofit may not guarantee the low financial burden due to the heating bills. Therefore, it is recommended for the age groups 35-55 and 55-65 to invest into the advanced energy efficiency measures, so that they were not threatened by the fuel poverty at the solid age. This recommendation should be especially considered by adding space extensions that increase the overall heating demand. The recommended retrofit packages of the analyzed apartment for different resident groups are shown in the Fig. 147. As the apartment is not located in the ground floor, the elevator is needed.

Fig. 147 Recommended retrofit module combinations for different age groups in the apartment 2B on the 4th floor 140

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3.4.3.2 The best case: Apartment 2B, 2nd floor Table 43 Main geometrical properties of the analyzed retrofit packages Existing

AFA = TFA = 47,23 m² A/V = 0,22

1

1+K

1+K+L

AEW2 = 6,9 m² Aw = 9,7 m²

AEW2 = 18,4 m² Aw = 11,4 m²

AEW2 = 18,4 m² Aw = 11,4 m²

1+Ws

1+K+Ws

AEW2 = 3,8 m² Aw = 12,8 m²

AEW2 = 15,3 m² Aw = 14,5 m²

AEW2 = 15,3 m² Aw = 14,5 m²

AEW1 = 9,4 m² AFA = TFA = 51,93 m² A/V = 0,16

AEW1 = 4,3 m² AFA = TFA = 55,95 m² A/V = 0,20

AEW1 = 4,3 m² AFA = TFA = 60,36 m² A/V = 0,18

1+K+L+Ws

All the possible geometry variants of the apartment 2B_2 are shown in the Table 43. This apartment in the 2nd floor has about two times lower space heating energy demand than the average of the building (Fig. 150). The space heating energy balance for the basic retrofit package (Fig. 148) reveals that the lower energy demand is caused by two factors. Firstly, the apartment has a very low ratio between the exterior surface area and the volume, therefore the transmission losses are limited. Secondly, it gets more solar gains, because the apartments in upper floors are less shaded by the built environment and all the windows are oriented to the south. The same figure shows, that the energy losses through ventilation and transmission are similar. As most of the transmission losses are caused by the windows, the space heating demand can be almost eliminated. However, after implementation of the advanced energy efficiency measures (modules Ws, WQ and V) a small heating demand is still present, as the share of not useful energy gains significantly increases (Fig. 149). This happens due to the increased solar gains through the bigger south windows, which do not always correlate with the heating demand. Despite the better thermal quality of the windows, their total transmission losses are only slightly reduced, because the total window area is enlarged.

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Losses 140

Unuseful gains Ventilation

120

Transmission

100 kWh/(m²a)

Exterior walls; 5,7

Gains

Internal gains 80 60 40

Windows; 27,4

Space heating energy demand Solar gains

20

0,9 27,8

28,3

23,1

33,1

11,3

0

Fig. 148 Useful energy balance for the basic retrofit package (right) and transmission losses regarding the construction type (left)

Exterior walls; 4,5

Windows; 26,5

Space heating energy demand, kWh/m²a

Fig. 149 Useful energy balance for the advanced retrofit package 1+Ws+WQ+V (right) and transmission losses regarding the construction type (left)

140

Existing = 139

120

1

100

+WQ

80

+WQ+Ws

60

+V

40 20

EnerPH = 25 27 25 23 11

8

8

31 29 27 16 13 13

29 27 25 15 12 12

1+K

1+K+L

+WQ+V +WQ+Ws+V

0 1

Fig. 150 Space heating energy demand of the apartment 2B on the 3rd floor for various retrofit packages 142

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The operation costs range between 2,15 and 3,40 EUR/(m²a), which is about 30% lower than the average (Fig. 151). As a result, the total costs savings exceed the average by 12% (Fig. 152).

Therefore, the payback periods of the same retrofit packages are by 2-4 years below the average (Fig. 153). The qualitative relations between the different retrofit module combinations remain the same. In case of the most energy efficient variants, the operation costs savings covers the assumed investment in less than 16 years. The most economic efficient package remains the 1+V.

Operation costs, EUR/(m2a)

12

Existing = 11,82

10

1

8

+WQ

6

+WQ+Ws +V

4 2

3,85

3,79 2,88 2,77

3,00 2,90

2,08 1,89 1,87

3,57 2,26 2,08 2,06

+WQ+V 2,78 2,69

2,10 1,93 1,91

+WQ+Ws+V

0 1

1+K

1+K+L

Total operation costs savings, %

Fig. 151 Operation costs of the apartment 2B on the 3rd floor for various retrofit packages 0% -10% -20% -30% -40% -50% -60% -70% -80% -90% -100%

1 -73%

-81%

-70%

-83%

-77%

-71%

-74%

-77%

-79%

+V

-71% -79%

-79%

-82%

+WQ +WQ+Ws

-61%

-61%

-65%

-70%

-79%

+WQ+V +WQ+Ws+V

1

1+K

1+K+L

Fig. 152 Total operation costs savings of the apartment 2B on the 3rd floor for various retrofit packages

payback period, years

25

20 15 10

20,8 17,1

16,7

1

22,0

20,4

19,3

+WQ

15,9

+WQ+Ws 20,5

16,9

22,2

20,8

14,6

16,3

18,1

19,6

21,8

19,3

20,8

+V

+WQ+V

05

+WQ+Ws+V 00 1

1+K

1+K+L

Fig. 153 Payback periods of the apartment 2B on the 3rd floor for various retrofit packages 143

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The benefits of each analyzed retrofit package are summarized in the Table 44. As no special functional improvements are available and the lower energy efficiency is not considered, the added values are equal to the apartment 2B_4 (average case). The gradual value increase by separate retrofit packages is illustrated in the Fig. 154. The possible improvements in a single apartment (modules W and B) increase the total apartment value by more than a half. After implementation of all the functionality modules the initial value is almost doubled. The generated profit exceeds the investment by about 1,5-3 times.

Table 44 Inputs for the calculations of the added value for the apartment 2B on the 3rd floor Additional floor are in reference to existing, m² 4,70 m²

Square meter price EUR/m² 1330

1+B+W

4,70 m²

1390

1+B+W + K

8,72 m²

1470

1+B+W +K+L

13,13 m²

1470

1+B+W +K+L+E

13,13 m²

1520

EUR

Retrofit package 1

45000 40000 35000 30000 25000 20000 15000 10000 5000 0

84% 70% 43%

49%

Functional improvements in reference to the existing conditions Improved technical quality More space for storage Improved technical quality More space for storage Exterior space (balcony and winter gardens) Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen and dining area Improved technical quality More space for storage Exterior space (balcony and winter gardens) Decent kitchen and dining area Barrier-free accessibility

91%

100% 80% 60% 40%

0%

20% 0%

Total investment, EUR Total added value, EUR

Value increase in reference to the existing, %

Fig. 154 Additional value generation due to the modules for functionality: B, W, E, K and L

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Fig. 155 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners As seen in the Fig. 155, the heating costs of any of the retrofit packages do not come close the fuel poverty limit of a household with a single pensioner. This means that the threat of the fuel poverty is effectively eliminated for the whole assessed time period. Therefore, no additional energy efficiency measures are actually needed. However, the big high quality windows can be suggested as a functional improvement, not as an energy efficiency measure. The recommended retrofit packages of the analyzed apartment for different resident groups are shown in the Fig. 156.

Fig. 156 Recommended retrofit modules for different resident groups

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3.4.3.3 The worst case: Apartment 2AE on the ground floor Table 45 Main geometrical properties of the analyzed retrofit packages: Apartment 2AE on the ground floor Existing

AFA = TFA = 47,23 m² A/V = 0,22

1

1+K

1+K+L

AEW2 = 7,1 m² Aw = 9,7 m²

AEW2 = 19,0 m² Aw = 11,4 m²

AEW2 = 24,2 m² Aw = 9,7 m²

1+Ws

1+K+Ws

AEW2 = 4,6 m² Aw = 12,1 m²

AEW2 = 16,5 m² Aw = 13,8 m²

AEW2 = 21,8 m² Aw = 12,1 m²

AEW1 = 47,0 m² AR = 59,38 m² AFA = TFA = 51,93 m² A/V = 0,75

AEW1 = 41,7 m² AR = 64,18 m² AFA = TFA = 55,95 m² A/V = 0,77

AEW1 = 38,2 m² AR = 68,98 m² AFA = TFA = 60,36 m² A/V = 0,74

1+K+L+Ws

All the possible geometry variants of the apartment 2AE_0 are shown in the Table 44. The space heating energy balance for the basic retrofit package (Fig. 157) shows much higher transmission losses and less solar gains. The same figure demonstrates that the energy losses through transmission are more than 2 times higher than the ventilation losses. Therefore, the relative effect of the ventilation heat recovery is lower. The most of transmission losses happen through the basement ceiling and exterior wall, which cannot be improved by the advanced modules (Fig. 158).

All things considered, the space heating demand cannot achieve the EnerPH-standard in any retrofit package. These values are about 50% above the average of the building (Fig. 159).

146

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Thermal bridges; 2,3

Losses

Exterior walls; 18,0

140

Not useful gains Ventilation

120

Transmission

100

0,0

80

29,2

kWh/(m²a)

Windows; 29,0

Gains

Internal gains 78,6

60 40

Basement ceiling; 21,4

Space heating energy demand Solar gains

70,8

20

10,1 11,3

0

Fig. 157 Useful energy balance for the basic retrofit package (right) and transmission losses regarding the construction type (left) Thermal bridges; 2,3

Exterior walls; 17,0

Windows; 26,3

Basement ceiling; 21,4

Fig. 158 Useful energy balance for the advanced retrofit package 1+WQ+Ws+V (right) and transmission losses regarding the construction type (left) Existing = 139 Space heating energy demand, kWh/m²a

140 120

1

100 80 60

+WQ 82

85

76 77 59

40

54 55

+WQ+Ws 79 79

76 63 58 59

+V

71 71 56 52 52

+WQ+V +WQ+Ws+V

20

EnerPH = 25

0 1

1+K

1+K+L

Fig. 159 Space heating energy demand of the apartment 2AE on the ground floor for various retrofit packages 147

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

The operation costs are between 5,37 and 6,68 EUR/(m²a), which is about 40% higher than the average of the building (Fig. 160). As a result, the total costs savings are about 20% below the average (Fig. 161). Therefore, the payback periods of the same retrofit packages are by 6-9 years longer than the average (Fig. 162). The qualitative relations between the different retrofit module combinations remain the same. In case of the most energy efficient variants, the operation costs savings covers the assumed investment in less than 25 years.

Operation costs, EUR/(m2a)

12

Existing = 11,82

10

1 +WQ

8

6

6,92

4

6,38

+WQ+Ws

6,88

6,40

6,40

5,59 5,93

6,37

5,63

2

6,25

5,65 5,96

5,80 5,77

5,68

+V

5,10 5,39

5,13

+WQ+V +WQ+Ws+V

0 1

1+K

1+K+L

Total operation costs savings, %

Fig. 160 Operation costs of the apartment 2AE on the ground floor for various retrofit packages 0% -10% -20% -30% -40% -50% -60% -70% -80% -90% -100%

-41% -45% -48% -36% -40% -48%

-36% -40% -43% -31% -36% -43%

-38% -42% -45% -32% -37% -45%

1 +WQ +WQ+Ws +V +WQ+V +WQ+Ws+V

1

1+K

1+K+L

Fig. 161 Total operation costs savings of the apartment 2AE on the ground floor for various retrofit packages 40 Payback period, years

35

30 25 20

15 10

33,4

30,5

+WQ +WQ+Ws

24,0 32,6

26,1

1

34,1

29,6

26,8

26,0

34,3

33,3

23,0

24,7

29,0

30,3

33,4

30,0

31,1

+V +WQ+V

05

+WQ+Ws+V

00 1

1+K

1+K+L

Fig. 162 Payback periods of the apartment 2AE on the ground floor for various retrofit packages 148

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The apartments in the ground floor have different qualities than the other ones. On the one hand, they are barrier-free accessible through the single stair run and the terrace. Therefore they do not need to share costs for the elevator. On the other hand, they are heavily shaded by the built environment and such poor daylight conditions cannot be improved due to the retrofit. On the real estate value estimation it is assumed that these two factors neutralize each other. The further advantage of the apartments in the ground floor is that their value can be significantly (by about 80%) increased without collaborative actions with the neighbors. This is because the terrace can be any time purchased from the apartment owner association.

Table 46 Inputs for the calculations of the added value for the apartment 2AE on the ground floor Retrofit package 1

Additional floor are in reference to existing, m² 4,70 m² Terraces: - 19 m² north - 13 m² south 4,70 m² Terraces: - 19 m² north - 13 m² south

Square meter price EUR/m² 1280

1+W+K

8,72 m² Terraces: - 15 m² north - 13 m² south

1380 (apartment) 500 (terrace) 1630 (total)

1+W+K+L

13,13 m² Terraces: - 11 m² north - 13 m² south

1380 (apartment) 500 (terrace) 1575 (total)

1+ W

1300 (apartment) 500 (terrace) 1610 (total)

96%

60000

Functional improvements in reference to the existing conditions Improved technical quality More space for storage Exterior space (terrace) Barrier free Improved technical quality More space for storage Barrier free Energy consumption above average Diverse exterior space (terrace and winter gardens) Improved technical quality More space for storage Barrier free Energy consumption above average Diverse exterior space (terrace and winter gardens) Decent kitchen Improved technical quality More space for storage Exterior space (balcony and winter gardens) Barrier free Energy consumption above average Diverse exterior space (terrace and winter gardens) Decent kitchen and dining area

104% 100%

79%

50000

80%

EUR

40000

60%

43%

30000

Total added value, EUR

40%

20000

10000

Total investment, EUR

20%

0%

0

0% Existing

1

1+W+T

1+T+W+K

Value increase in reference to the existing, %

1+W+T+K+L

Fig. 163 Additional value generation due to the modules for functionality: T, W, K and L 149

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 164 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners As seen in the Fig. 164, the apartment is basically not suitable for a single pensioner, as even with the most advanced retrofit packages the fuel poverty cannot be effectively avoided. However, for two pensioners it is not a big problem. The proposed retrofit modules for the selected age groups are shown in the Fig. 165. As the apartment is already barrier-free accessible, the residents do not need to share costs for the elevator. This makes it very attractive for the young families and pensioners, which do not tend to make big investments, but at the same time need barrier-free solutions. The age groups with higher incomes can buy the whole terrace and should think about the full set of the advanced energy efficiency modules. The seniors are not likely to buy the whole available terrace. However, they could be allowed to establish flower gardens and further nourish them, because it can be treated as a communal use.

Fig. 165 Recommended retrofit modules for different resident groups 150

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.4.3.4 Equalization of the payback periods The results reveal that the payback periods of the same retrofit packages between the best and worst apartment can differ by almost 9 years. In order to ensure equal conditions and economic benefit for all the residents, the investment costs for different apartments should be adapted according to their operation costs. As the advanced retrofit modules deliver very similar absolute energy savings, the assessment of the basic retrofit packages is sufficient. In the Fig. 166 the occurring life cycle costs (sum of investment and cumulating operation costs) of the three analyzed apartments is compared with the costs, which would occur if no retrofit measures were taken.

Thereby the reference area is the existing apartment floor area (47,23 m²). Annual energy price increase of 3% is assumed. It is seen that the basic retrofit package begins to generate a profit after 19 years of operation for the average apartment. As this is the average value for the whole building, this payback period is the target value for the other apartments. In order to achieve this, the life cycle costs differences after 19 years must be removed by adding these differences to the initial investment. The life cycle costs after such adaption are shown in the Fig. 167. As the result, the investment for the least energy efficient apartment is reduced by 57 EUR/m², while the owner of the best apartment pays 28 EUR/m² more than the average.

600

500

351 EUR/m²

400

Average 300

Best

293

Worst

200

266

Existing

100

0 0

5

10

15

20

25

30

Years of operation

Fig. 166 Life cycle costs for the three analyzed apartments (basic retrofit package) and the existing building

151

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

600

EUR/m²

500

400

Average 300

192

Best Worst

200

163

Existing

100

107 0 0

5

10

15

20

25

30

Years of operation

Fig. 167 Life cycle costs for the three analyzed apartments (basic retrofit package) and the existing building after adaption Such high cost differences would of course cause lots of questions for the affected residents. In this analysis very rough investment estimations were made. It may lead to the very inaccurate absolute values, which cannot act as a reliable base for the fair investment adaption. For this reason, a more detailed and transparent costs assessment in collaboration with the apartment owners is required. The target of the performed analysis was to emphasize the possibly unfair sharing of the investment costs between the apartments. The payback periods of the basic retrofit package for the three analyzed apartments with and without investment adaption are shown in the Fig. 168.

30

PAyback period, years

25

26,0

20 19,0 15

Normalized

16,7

Not normalized 10

18,8

18,8

18,8

05 00 Average

Best

Worst

Fig. 168 Payback periods of the basic retrofit package for the three analyzed apartments before and after the investment adaption

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

EUR/m²

In order to access a long-term economic benefit of the retrofit, the occurring life cycle costs should be compared with the added value. It can be assumed, that a long-term economic benefit is present, when the life cycle costs after a 30 years period do not exceed the added value. Such comparison is presented in the Fig. 169. The yellow line represents the added value, which is equal for all three apartments after the basic retrofit. Its increase is not considered in order to compensate the possible maintenance and repair costs, which are in turn not included in the LCC. It can be seen that the basic retrofit of the least energy efficient apartment 2AE_1 cannot be considered as a long-term cost-efficient solution, because its life cycle costs exceeds the added value after about 26 years of operation. Therefore, the advanced functional modules are needed to maintain the real estate value. In contrast, a selling of the other two apartments after 30 years of operation would still generate a profit for their owners even if no additional functional improvements were implemented.

500 450 400 350 300 250 200 150 100 50 0

LCC Average LCC Best LCC Worst Added value 0

5

10

15

20

25

30

Years of operation

Fig. 169 Comparison of the three analyzed apartments regarding the life cycle costs and added value (for basic retrofit package)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

3.4.4

Façades

Fig. 170 Existing: back and front facades

Fig. 171 Basic retrofit: back and front facades

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 3. Retrofit with prefabricated timber elements

Fig. 172 Advanced retrofit 1+W+B+E: back and front facades

Fig. 173 Advanced retrofit 1+W+B+E+K+L: back and front facades

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „ Retrofit of Lithuanian large concrete panel buildings with prefabricated timber elements “ 4. Conclusions

4

Conclusions

In the master‟s thesis a retrofit strategy for large concrete panel buildings in Vilnius (Lithuania) is created. Firstly, a thorough investigation of the existing conditions is made. Poor floor plan layout quality due to the tiny kitchens and storage areas, lack of barrier-free accessibility, monotonic and deteriorated façade appearance and abandoned surroundings are the primary causes for the unattractiveness of these blocks. Moreover, a quarter of population in these districts is pensioners, who are pushed into the fuel poverty by the high heating bills. The high heat demand is caused by the low thermal quality of the building envelope and inefficient heating as well as DHW systems, which also lead to low thermal comfort. Poor collaboration of the condominium owners and a lack of responsibility for the common property cause bad maintenance of the building and emergence of the technical defects, although the structure still has big load reserves. As the public authorities already plan urban revitalization projects of the socialist housing estates, it can be expected that the problems with the surroundings will be solved. The state-supported energy retrofits attain up to 60% heating energy savings. However, they rarely improve blocks‟ functionality and air-quality. In consequence the retrofitted houses may remain unattractive for the newcomers. What is more, the calculated energy savings often do not coincide with the real ones, discrediting the whole idea of energy retrofit. Regarding the innovative and sustainable construction and design methods, a significant growth is identified in the local fields of BIM and prefab timber construction. These offer such benefits like material and costs savings as well as high design and workmanship quality.

However, these potentials are currently not embraced in the refurbishment sector.

The findings of the research suggested a creation of a prefab modular retrofit system. It enables buildings adaptability to the residents needs by the retrofit modules. These are variable retrofit measures like space extensions, windows and ventilation and have basic and advanced versions, which can be replaced by each other, allowing future development of the house. Detachability of the building elements, high workmanship quality, minimal disturbance of the residents, and the use of sustainable local materials are ensured by employing the methods of the façade refurbishment system with large prefab timber frame panels (TES EnegyFacade). The typical TES-workflow is modified according to the local specifics. The fundamental part of the proposed process is a digital parametric model of a typical retrofit project, which is applicable for a large number of buildings of the same type. It includes all the possible retrofit modules and acts as a data container. The users (residents) can customize the final design on their own by using the retrofit configurator, where functional, environmental and economic consequences of every retrofit module combination are understandably presented. In contrast to the typical TES-process, the detailed geometry survey is avoided by introducing two types of the façade panels, which can be adjusted on the existing façade geometry on site. This and the standardized geometries of the analyzed buildings make an idea of mass-produced façade panels viable. The construction design becomes unnecessary, as the automatically generated retrofit model is sufficient for ordering the mass-produced products and the respective installation works. In this way, the residents are effectively involved in the design process, their needs and financial capabilities automatically considered, responsibility for their own property increased, the collaboration in small groups motivated, design costs reduced, and innovative and sustainable construction methods applied.

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In order to elaborate this retrofit system and test its feasibility, a typical retrofit project is created for a representative large panel building type 1-464LI-18/2 (5-storey, 30 apartments) in Vilnius.

Substantial functional improvements are enabled by the space extensions. Due to the basic retrofit gained additional 9,4% apartment floor area can be used for storage. By materializing a full set of the possible advanced space extensions, the total apartment floor area is enlarged by 26%.

Thereby the most useful is the kitchen extension, which allows arranging a decent dining area. An optional addition of an elevator allows a high level of barrier-free accessibility. Implementation of these advanced modules need to be approved by the affected condominiums. In contrast, the prefab balconies can be added individually. All the space extensions are designed in such way that they do not block the daylight for the neighbors. Terrace on the ground floor is also possible, as the site level around the building is lifted by using the concrete, which was deconstructed during the preparation of the building structure for the initial retrofit. In order to attain high energy efficiency and good air quality and to allow the further use of the existing quite new windows, a decentralized demand controlled ventilation system, interlinked with the double windows, is proposed. It is included in the basic retrofit and has a twofold benefit. Firstly, the heat losses of the inner window are reduced by about 20-40%. Secondly, the pre-warmed air is supplied into the room through humidity sensitive air inlets, reducing the ventilation losses. While the basic ventilation module includes only an exhaust air ventilator, an exhaust air heat pump (EAHP) of optimal 11 kW heating capacity is added to it on the advanced version. It enables a ventilation heat recovery of 67% and can be installed in a single group of 5 apartments, located on top of each other. The produced heat is used both for heating and DHW preparation.

Totally 18 retrofit module combinations were separately evaluated for the whole house and three apartments, which have the lowest, highest and average energy demand. Thereby the energy demand, costs, CO2 emissions, payback periods and added values were calculated using the principle of the retrofit configurator. Depending on the retrofit packages, about 60-80% of the total final energy for heating, ventilation and DHW in the whole house can be saved. The space heating energy demand values below 25 kWh/(m²a) are achievable with advanced ventilation and better windows. This complies with the Passive House standard for the refurbishment EnerPHit. The further reduction of primary energy demand and CO2 emissions can be predicted, as the state plans higher RES-portion in the energy mix. Even assuming a fairly high basic retrofit price of 250 EUR/m², a quite satisfactory payback period of about 19 years is reached. The highest costefficiency is achieved by adding the advanced ventilation module. The payback periods for the different apartments are equalized by adapting the initial investment size to the calculated energy savings. Due to the considerable increase of the square meter price and total floor area, the total real estate value of the condominiums can be doubled. This requires a relative low investment and ensures a high profit for the owners in case of selling their property. The optimal retrofit package for a single condominium depends on its location in the building and the residents‟ needs and their financial resources. This generates a different façade appearance in every particular case.

Nevertheless, the whole image is not chaotic, as the distinctions still belong to the same design.

To sum up, the proposed retrofit system reprograms the essential code of the large panel buildings: standardized blocks for the former uniform socialist society are transformed into the individual and organically changing houses for the contemporary people.

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6

Table of Figures

Fig. 1 Mass-housing estates: left – district Lazdynai in Vilnius (Lithuania), year 1966; right – district Vällingby in Stockholm (Sweden), year 1953 (5) ............................................................................. 1 Fig. 2 Building stock in the city of Vilnius (6), (7) ............................................................................. 1 Fig. 3 Key information about the country and the capital city ........................................................... 2 Fig. 4 Large panel buildings in the context of the city of Vilnius ....................................................... 5 Fig. 5 Urban sprawl in Vilnius in 2001-2011 (6) ............................................................................... 6 Fig. 6 District heat in Lithuania (6): gross consumption and local generation (left); prices (right) ..... 8 Fig. 7 Electricity in Lithuania (6): gross final consumption and local generation (left); prices (right) . 9 Fig. 8 Prefab concrete panel building type 1-464LI-18/2 (5/30/2): front and back facades............. 10 Fig. 9 Type 1-464LI-18/2: Ground floor plan.................................................................................. 11 Fig. 10 Type 1-464LI-18/2: Section ............................................................................................... 12 Fig. 11 Type 1-464LI-18/2: Front façade ....................................................................................... 13 Fig. 12 Type 1-464LI-18/2: Back façade ....................................................................................... 13 Fig. 13 Worst case environment scenario and possible orientation range ..................................... 14 Fig. 14 Daylighting scheme of the building and its environment .................................................... 15 Fig. 15 Sun hours in the ground floor rooms of various orientations .............................................. 15 Fig. 16 Daylight factors on the working plane (0,85 m above the floor level) in the ground floor .... 16 Fig. 17 Static scheme with live loads............................................................................................. 18 Fig. 18 bending moments in basement transverse walls (24) ........................................................ 19 Fig. 19 Joint of interior and exterior walls and floor slab (sections 1-1 and 3-3) ............................. 19 Fig. 20 Walls panels joint: horizontal and vertical section (28), photo from the outside: 3 – floor slab; 4 – mortar joint; 5 – monolithic concrete, 6 – bitumen hydro isolation; 7 – elastic sealing; 8 – tarred tow; 9 – sealing resin; 10 – cement mortar.......................................................................... 20 Fig. 21 End of the gable wall panel ............................................................................................... 21 Fig. 22 Exterior finishes of the building series 1-464LI (left to right): sand-cement plaster; ceramic coating; washed concrete ............................................................................................................. 21 Fig. 23 Typical exterior wall panel ................................................................................................. 22 Fig. 24 Exemplar interior wall panel and its reinforcement (24) ..................................................... 23 Fig. 25 Basement ceiling construction: left - initial design (28); right – probable existing situation . 24 Fig. 26 Typical floor slab and its reinforcement (24) ...................................................................... 24 Fig. 27 Roof construction .............................................................................................................. 25 Fig. 28 Protruding balcony slab: intact and weathered, with exposed reinforcement. .................... 26 Fig. 29 One-pipe heating system (33): 1 – horizontal distribution pipes (flow), 2 – horizontal distribution pipes (return), 3 – radiators, 4 – standpipe (return), 5 – standpipe (flow), 6 – cross valve. ............................................................................................................................................ 27 Fig. 30 Heating system: left – modernized technical room (34); right – typical radiators (35) ........ 28 Fig. 31 Domestic hot water (DHW) system (33): 1 – heat exchanger, 2 – horizontal DHW distribution pipes (flow), 3 – horizontal circulation pipes (return), 4 – DHW standpipe (flow), 5 – circulation standpipe (return), 6 – water tap, 7 – towel warmer, 8 – circulation pump, 9 – domestic cold water meter, 10 – non-return valves, 11 – valves................................................................... 29

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 6. Table of Figures

Fig. 32 DHW circulation system: left – insulated pipes in the basement (34), right – towel heater, formed from the DHW circulation return pipes (35) ....................................................................... 29 Fig. 33 Natural ventilation system: vertical exhaust air shafts and supply trough windows ............ 31 Fig. 34 Energy balance for the DHW and heating system, based on ISO 13790 (see Appendix 8.4) ..................................................................................................................................................... 32 Fig. 35 Real space heating energy consumption map of the city of Vilnius (left) and distribution of the real heating energy consumption values of the analyzed type 1-464LI-18/2 (right) (12) ......... 33 Fig. 36 Real average final energy consumption values ................................................................. 34 Fig. 37 Monthly values of the exterior air temperatures and total global sun radiation ................... 35 Fig. 38 The analyzed building with environment in designPH ........................................................ 36 Fig. 39 Useful heating energy balance of the existing building (right) and the transmission losses (left) .............................................................................................................................................. 37 Fig. 40 Monthly useful heating energy balances of the existing building ........................................ 37 Fig. 41 Final energy balance for DHW and heating systems of the existing building ..................... 37 Fig. 42 Final energy consumption for DHW, circulation and heating: comparison between the PHPP calculations and the real average value (left) ...................................................................... 38 Fig. 43 Reference values: annual operation costs; primary energy demand; CO2 emissions ........ 39 Fig. 44 Risk of fuel poverty for various households structure (typical 2-room apartment (47,23 m²) in the large concrete panel building type 1-464LI-18/2) ................................................................. 40 Fig. 45 Maximal space heating energy demands Qh of various building classes for residential buildings of 1700 m² floor area (21) .............................................................................................. 41 Fig. 46 Energy balances in the approved investment plan of a large panel building of type 1-464LI18/2 (34): existing conditions (left) and retrofit (right) .................................................................... 47 Fig. 47 Calculated energy costs, credit repayment and costs savings in the approved investment plan of a large panel building of type 1-464LI-18/2 (34): left - using the calculated values, right – using the real consumption value as a reference .......................................................................... 47 Fig. 48 Building of type 1-464LI-18/1 after the retrofit (Tuskulėnų Street 28) and its actual energy consumption for the space heating in three last heating seasons (12) .......................................... 48 Fig. 49 Annual expenses before and after the retrofit, regarding different energy prices and state support in the year 2014 and 2016 ................................................................................................ 49 Fig. 50 Revitalization plan of the soviet district Ţirmūnai in Vilnius (arch. PUPA, Vilnius city municipality) (14)........................................................................................................................... 50 Fig. 51 Modification of a large panel building in the city of Leinefelde (Germany), Stefan Forster Architects (54)............................................................................................................................... 51 Fig. 52 Interior space before and after the transformation in a 16-storey housing block in Paris (France), Lacaton & Vassal (55) ................................................................................................... 52 Fig. 53 Transformation scheme – addition of a new living space and a balcony, Lacaton & Vassal (56) ............................................................................................................................................... 52 Fig. 54 Energy retrofit with prefabricated timber elements in Grüntenerstr, Augsburg (Germany), lattkearchitekten (57) .................................................................................................................... 53 Fig. 55 Workflow in the TES-process (58) ..................................................................................... 53 Fig. 56 ELEMENTAL social housing project in Iniqueqe, Chile: state funded concrete part of the building and individual extensions in between (55)........................................................................ 54 163

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 6. Table of Figures

Fig. 57 Life cycle of the residents .................................................................................................. 58 Fig. 58 Workflow in the TES-process (10) .................................................................................... 61 Fig. 59 Process map of the suggested retrofit system ................................................................... 62 Fig. 60 Surface deviations of exterior walls: front and side façades .............................................. 66 Fig. 61 Stacked façade panel structure ......................................................................................... 66 Fig. 62 Elevation view of the façade panel joints ........................................................................... 67 Fig. 63 possible façade panel layouts: horizontal (left) and vertical (right) ..................................... 67 Fig. 64 Passage between courtyards – the main restriction for transportation of large prefabricated elements ....................................................................................................................................... 68 Fig. 65 Static schemes in case of sufficient load reserves for space extensions ........................... 69 Fig. 66 Static scheme in case of sufficient load reserves for balconies ......................................... 69 Fig. 67 Possible TES-element connections to the base in case of sufficient load reserves (66) .... 70 Fig. 68 Static schemes in case of insufficient load reserves for space extensions......................... 71 Fig. 69 Static scheme in case of insufficient load reserves for balconies....................................... 71 Fig. 70 Possible TES-element connections to the base in case of insufficient load reserves (66) . 71 Fig. 71 Comparison of final heat energy and space heating energy: existing conditions and preliminary retrofit according to the minimal requirements of the C class building ......................... 73 Fig. 72 Detailed final energy balance of the C-class building after the preliminary energy analysis73 Fig. 73 Transmission losses of the C-class building ...................................................................... 73 Fig. 74 Existing situation (L0+K0) and Retrofit steps (L1+K1; L1+K2; L2+K2) of living-diningcooking area ................................................................................................................................. 74 Fig. 75 Process: retrofit modules K1 and K2 ................................................................................. 75 Fig. 76 Daylight analysis for a north oriented kitchen in the ground floor ....................................... 76 Fig. 77 Retrofit steps for the living room: existing situation (L0), horizontal extensions L1 and L2 . 77 Fig. 78 Process: retrofit modules L1 and L2 .................................................................................. 78 Fig. 79 Daylight analysis for a living room in the ground floor ........................................................ 79 Fig. 80 Retrofit steps of the bedroom: R0 (existing), R1 and R1+B (with balcony) ........................ 80 Fig. 81 Design of the balconies regarding the daylight situation in the existing and retrofitted building (section of the 1st floor) .................................................................................................... 81 Fig. 82 Process: retrofit modules R1 and R1+B ............................................................................ 81 Fig. 83 Daylight analysis for a bedroom in the ground floor ........................................................... 82 Fig. 84 Structure of a individually attachable balcony (Retrofit module B) ..................................... 83 Fig. 85 Retrofit steps of entrance area: BF0 (existing), BF1 (basic), BF2 (with elevator) ............... 85 Fig. 86 Process: retrofit modules BF1 and BF2 ............................................................................. 86 Fig. 87 Exterior wall, plan view: EW2 (left); EW1 (right) ................................................................ 88 Fig. 88 Mounting process of the TES-panels................................................................................. 89 Fig. 89 Façade panel types ........................................................................................................... 90 Fig. 90 Roof joint with the TES-panel ............................................................................................ 92 Fig. 91 Roof and façade panel joint: temperature curves and thermal bridge calculation .............. 94 Fig. 92 Mounting process of the roof and TES-panels ................................................................... 95 Fig. 93 Base joint .......................................................................................................................... 96 Fig. 94 Temperature simulation and definition of the thermal bridge on the base joint .................. 97

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 6. Table of Figures

Fig. 95 Temperature simulation and definition of the thermal bridge on the connection between interior walls in the basement and ground floor ............................................................................. 98 Fig. 96 Main components of the double window ............................................................................ 98 Fig. 97 Isotherms and thermal bridges for the first window installation variant (without exterior glazing) ....................................................................................................................................... 101 Fig. 98 Isotherms and thermal bridges for the first window installation variant (without exterior glazing) ....................................................................................................................................... 101 Fig. 99 Energy balance of the double windows ........................................................................... 102 Fig. 100 Different air flow and temperatures distribution in the double window cavity: without air inlet (left) and with air inlet (right) ................................................................................................ 103 Fig. 101 Average monthly temperature reduction factors during the heating season for the south and north oriented 1,45x1,55 m windows in the 2nd storey, regarding their thermal quality: without air inlet (air flow 11,5 m³/h), with air inlet (air flow 24,0 m²/h) ....................................................... 104 Fig. 102 Therm temperature simulation of the exterior wall and window junction ........................ 105 Fig. 103 Principal scheme of window installation ........................................................................ 106 Fig. 104 Detail window element W1 ............................................................................................ 107 Fig. 105 Mounting process of the window element, based on the module W1............................. 108 Fig. 106 Retrofit variants of the kitchen window: WK1 and WK2 ................................................. 109 Fig. 107 Retrofit variants of the living room window: WL1 and WL2 ............................................ 110 Fig. 108 Retrofit variants of the bedroom window: WR1 and WR2 .............................................. 111 Fig. 109 Retrofit variants of the balcony door: regular floor - WB1; ground floor - WBG1 and WBG2 ................................................................................................................................................... 112 Fig. 110 Ventilation system scheme V1 ...................................................................................... 113 Fig. 111 Energy balance ............................................................................................................. 113 Fig. 112 Average monthly exterior and supply air temperatures during the heating season, window WL1, south, 3rd floor .................................................................................................................... 114 Fig. 113 Average daily ventilation heat recovery rates during the heating season, window WL1, south, 3rd floor ............................................................................................................................. 115 Fig. 114 Average hourly ventilation heat recovery rates for separate months, window WL1, south, 3rd floor........................................................................................................................................ 115 Fig. 115 Humidity sensible air inlet AERECO ZFH 40: 3D view and projections (69) .................. 116 Fig. 116 Relation between supply air flow, relative humidity and pressure differences (69) ........ 116 Fig. 117 A detail drawing of on a plastic window installed humidity sensible air inlet AERECO ZFH 40 with canopy WHI 05 on the exterior side (69) ......................................................................... 117 Fig. 118 Mechanical exhaust air ventilation system with heat recovery through EAHP ............... 117 Fig. 119 Energy balance in winter: EAHP supports heating system ............................................ 118 Fig. 120 Energy balance in summer: EAHP generates heat for DHW system ............................. 118 Fig. 121 Correlation between the COP-values and EAHP heat capacity (exhaust air flow 1680 m³/h) ........................................................................................................................................... 119 Fig. 122 Monthly heat demand (incl. distribution losses) of the basic retrofit package and the total heat outputs from the EAHP of various capacities....................................................................... 120 Fig. 123 Monthly electricity and district heat demand for various EAHP capacities ..................... 120

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 6. Table of Figures

Fig. 124 Search for the optimal EAHP capacity regarding the cost- and energy efficiency (in reference to the retrofit package 1) ............................................................................................. 121 Fig. 125 Monthly final heat energy demand regarding different energy sources and purposes.... 122 Fig. 126 Heat pipes distribution scheme on the south façade ..................................................... 123 Fig. 127 Applied retrofit configuration process ............................................................................ 127 Fig. 128 Space heating energy demand of the building for various retrofit packages .................. 129 Fig. 129 Useful energy balance for the basic retrofit package 1 (right) and transmission losses regarding the construction type (left) ........................................................................................... 129 Fig. 130 Useful energy balance for the advanced retrofit package 1+WQ+Ws+V (right) and transmission losses regarding the construction type (left) ........................................................... 129 Fig. 131 Final energy demand of the building regarding the energy source and energy use ....... 130 Fig. 132 Primary energy demand of the building for various retrofit packages ............................. 131 Fig. 133 Total primary energy savings of the building for various retrofit packages ..................... 131 Fig. 134 Annual CO2 emissions of the building for various retrofit packages .............................. 132 Fig. 135 Annual total CO2 savings of the building for various retrofit packages .......................... 132 Fig. 136 Annual operation costs of the building for various retrofit packages .............................. 133 Fig. 137 Annual total operation costs savings of the building for various retrofit packages .......... 133 Fig. 138 Average payback periods of various retrofit packages................................................... 134 Fig. 139 Useful energy balance for the basic retrofit package 1 (right) and transmission losses regarding the construction type (left) ........................................................................................... 137 Fig. 140 Useful energy balance for the advanced retrofit package 1+Ws+WQ+V (right) and transmission losses regarding the construction type (left) ........................................................... 137 Fig. 141 Space heating energy demand of the apartment 2B on the 4th floor for various retrofit packages .................................................................................................................................... 137 Fig. 142 Operation costs of the apartment 2B on the 4th floor for various retrofit packages ......... 138 Fig. 143 Total operation costs savings of the apartment 2B on the 4th floor for various retrofit packages .................................................................................................................................... 138 Fig. 144 Payback periods of the apartment 2B on the 4th floor for various retrofit packages ........ 138 Fig. 145 Additional value generation due to the modules for functionality: B, W, E, K and L ....... 139 Fig. 146 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners .................. 140 Fig. 147 Recommended retrofit module combinations for different age groups in the apartment 2B on the 4th floor ............................................................................................................................. 140 Fig. 148 Useful energy balance for the basic retrofit package (right) and transmission losses regarding the construction type (left) ........................................................................................... 142 Fig. 149 Useful energy balance for the advanced retrofit package 1+Ws+WQ+V (right) and transmission losses regarding the construction type (left) ........................................................... 142 Fig. 150 Space heating energy demand of the apartment 2B on the 3rd floor for various retrofit packages .................................................................................................................................... 142 Fig. 151 Operation costs of the apartment 2B on the 3rd floor for various retrofit packages ......... 143 Fig. 152 Total operation costs savings of the apartment 2B on the 3rd floor for various retrofit packages .................................................................................................................................... 143 Fig. 153 Payback periods of the apartment 2B on the 3rd floor for various retrofit packages........ 143 166

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 6. Table of Figures

Fig. 154 Additional value generation due to the modules for functionality: B, W, E, K and L ....... 144 Fig. 155 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners .................. 145 Fig. 156 Recommended retrofit modules for different resident groups ........................................ 145 Fig. 157 Useful energy balance for the basic retrofit package (right) and transmission losses regarding the construction type (left) ........................................................................................... 147 Fig. 158 Useful energy balance for the advanced retrofit package 1+WQ+Ws+V (right) and transmission losses regarding the construction type (left) ........................................................... 147 Fig. 159 Space heating energy demand of the apartment 2AE on the ground floor for various retrofit packages ......................................................................................................................... 147 Fig. 160 Operation costs of the apartment 2AE on the ground floor for various retrofit packages 148 Fig. 161 Total operation costs savings of the apartment 2AE on the ground floor for various retrofit packages .................................................................................................................................... 148 Fig. 162 Payback periods of the apartment 2AE on the ground floor for various retrofit packages ................................................................................................................................................... 148 Fig. 163 Additional value generation due to the modules for functionality: T, W, K and L ............ 149 Fig. 164 Development of the heating costs (of various retrofit packages) in comparison to the predicted fuel poverty limits of the households, composed of one or two pensioners .................. 150 Fig. 165 Recommended retrofit modules for different resident groups ........................................ 150 Fig. 166 Life cycle costs for the three analyzed apartments (basic retrofit package) and the existing building ....................................................................................................................................... 151 Fig. 167 Life cycle costs for the three analyzed apartments (basic retrofit package) and the existing building after adaption ................................................................................................................. 152 Fig. 168 Payback periods of the basic retrofit package for the three analyzed apartments before and after the investment adaption ............................................................................................... 152 Fig. 169 Comparison of the three analyzed apartments regarding the life cycle costs and added value (for basic retrofit package) ................................................................................................. 153 Fig. 170 Existing: back and front facades .................................................................................... 154 Fig. 171 Basic retrofit: back and front facades ............................................................................ 154 Fig. 172 Advanced retrofit 1+W+B+E: back and front facades .................................................... 155 Fig. 173 Advanced retrofit 1+W+B+E+K+L: back and front facades ............................................ 155

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7

List of tables

Table 1 Large panel building series in Vilnius ................................................................................. 4 Table 2 Requirements for the daylighting in multi-residential buildings.......................................... 14 Table 3 Main properties of the existing windows ........................................................................... 26 Table 4 Comparison of the main climatic parameters of the Lithuanian standard STR 2.01.09:2012 and PHPP climate dataset for Vilnius ............................................................................................ 35 Table 5 Main input parameters for energy calculations with PHPP ............................................... 36 Table 6 Thermal properties of the assessed building of type 1-464LI-18/2 and the respective requirements of various energy standards .................................................................................... 41 Table 7 Fire resistance requirements for building elements of the buildings of the 1st fire resistance level (50) ....................................................................................................................................... 42 Table 8 Economic forecast for the retrofitted building of type 1-464LI-18/1 (Tuskulėnų Street 28) 49 Table 9 SWOT analysis ................................................................................................................ 56 Table 10 Age groups of the residents and their living space preferences ...................................... 58 Table 11 Explanation of the components of the process map ....................................................... 61 Table 12 Measurement accuracy, allowed deviations and prefabrication tolerances ..................... 65 Table 13 Comparison between the horizontal and vertical façade panel arrangement .................. 67 Table 14 Implemented retrofit measures for the preliminary energy calculations .......................... 72 Table 15 Retrofit module K: summary ........................................................................................... 74 Table 16 Retrofit module L: summary ........................................................................................... 77 Table 17 Horizontal room extension: summary ............................................................................. 80 Table 18 Retrofit module BF: summary ......................................................................................... 84 Table 19 Exterior wall construction: TES-element on the existing wall (type EW1)........................ 88 Table 20 Exterior wall construction: TES-element as exterior wall (type EW2) .............................. 89 Table 21 Façade panel types: summary ....................................................................................... 91 Table 22 Research on the exterior wall prices............................................................................... 91 Table 23 Roof construction ........................................................................................................... 93 Table 24 Construction of the basement ceiling .............................................................................. 96 Table 25 Retrofit modules of the windows and their parameters ................................................... 99 Table 26 Thermal conductivity values of window elements for the simulation with Therm 7.3 ..... 100 Table 27 Thermal properties of the kitchen window WK1 ............................................................ 109 Table 28 Thermal properties of the kitchen window WK2 ............................................................ 109 Table 29 Thermal properties of the kitchen window WL1 ............................................................ 110 Table 30 Thermal properties of the kitchen window WL2 ............................................................ 110 Table 31 Thermal properties of the bedroom window WR1 ......................................................... 111 Table 32 Thermal properties of the bedroom window WR2 ......................................................... 111 Table 33 Thermal properties of the balcony door WB1 ............................................................... 112 Table 34 Thermal properties of the balcony door WBG1 and WBG2........................................... 112 Table 35 Retrofitted heating and DHW distribution pipes ............................................................ 123 Table 36 Total construction works price estimation (basic retrofit package) ................................ 124 Table 37 Final retrofit price estimation (basic retrofit package).................................................... 124 Table 38 Results of the configuration ant their calculation methods ............................................ 126 168

Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 7. List of tables

Table 39 Main geometric data of the analyzed retrofit packages on the building level ................. 128 Table 40 Space heating demand changes in separate apartments (retrofit package 1) .............. 135 Table 41 Main geometrical properties of the analyzed retrofit packages: apartment 2B on 4th floor ................................................................................................................................................... 136 Table 42 Inputs for calculation of the added value of the apartment 2B on the 4th floor ............... 139 Table 43 Main geometrical properties of the analyzed retrofit packages ..................................... 141 Table 44 Inputs for the calculations of the added value for the apartment 2B on the 3rd floor ...... 144 Table 45 Main geometrical properties of the analyzed retrofit packages: Apartment 2AE on the ground floor................................................................................................................................. 146 Table 46 Inputs for the calculations of the added value for the apartment 2AE on the ground floor ................................................................................................................................................... 149

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8

Appendix

8.1

Final energy consumption Final energy consumption in Lithuania

Final energy consumption in households

12%

Industry

20% 31%

Space Heating

7%

Transport Agroculture

Hot water

10%

Cooking

Services

33%

14%

Other

71%

Housholds

2%

Total final energy consumption in Lithuania and energy consumption in households (year 2009) (6) 8.1.1

Fuel prices 000

000

EUR/kWh

000

Natural gas Biofuel waste

000

Timber-based biomass Straw

000

Biogas

000

000 2010

2015

2020

2025

2030

2035

2040

2045

2050

Low fuel price scenario (18)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

8.2

Large panel building series – state of the art

8.2.1

Location

8.2.1.1 Demographic situation Demographic structure 2011

Population change 2001-2011

100% 80%

10%

15%

17%

25%

26%

22%

0%

5% 0%

21%

22%

30%

30%

29%

31%

16%

13%

11% 13%

12%

-5%

40% 20%

12% 31%

60% 31%

25%

-10%

-2%

-3%

-15% 14% 15%

12%

Vilnius

1605

0-15

15-25

13%

1-464A-LT 1-464LI

25-45

45-65

14% 120V

65+

-11%

-17%

-20%

-12%

-25% Vilnius

0-15

1605

15-25

1-464A-LT 1-464LI

25-45

45-65

120V

65+

Demographic situation in the chosen districts of large panel buildings (6) 8.2.1.2 Accessibility

Left: Time of journey from the soviet districts to the city center by public transport. Right: Stations of rentable bicycles.

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

8.2.2

Sociocultural and functional quality

8.2.2.1 Immediate proximity

1605 - Naujamiestis

1-464A - Ţirmūnai

1-464LI - Karoliniškės

120V - Šeškinė

Typical neighborhoods of large panel buildings The blocks of 1605 series are far away from bigger parks but have lots of mature deciduous trees in courtyards, which are partly blocking the daylight. Districts of 1-464A and 1-464LI look very similar: there are lots of green spaces outdoors, big parks and river banks are near. In districts of 120V only low level of vegetation can be found, parks or lakes are quite far away. In general, quite big outdoor spaces are poorly maintained (lack of benches, children playgrounds, street lighting and deteriorated paths). Therefore, their full potential is not used. Despite vegetation, sloping topographies and various configurations of buildings (especially of 1-464Li and 120V series), the soviet neighborhoods still look very similar and monotonic. The residents often try to enliven their environments. The most usual method – setting mini gardens in front of the windows, on the both side of the house. This is usually done by the owners of the ground floor apartments (especially elderly women) (see Appendix 8.2.2.1), although the land officially belongs to the municipality.

Lack of parking lots is another important issue in the districts. The real demand is about 0,75 car/household. However, in the older districts with high share of seniors, a third of the cars are used only occasionally (14).

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

Gardens in front of the buildings

Diversity of loggias in Karoliniškės district (collage)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

8.2.2.2 Layouts Comparison of large panel building series layouts Building series

1room

2room

3room

4room

Transition rooms

Kitchen, m²

Storage, 2 m²

Loggias, m²

5,67 5,90

Bathroom and WC, m² 2,43 2,87

1605 1-464A

31,90 28,70

45,90 45,60

58,30 48,60

-

yes yes

2,38 -

no

6,49

3,17

no

7,409,40

3,51

0,723 2,40 1,264 3,23

3,98 4,3711,78 3,745 7,48 4,405,80

1-464LI

33,25

47,23

61,21

78,23

1

120V

36,56

49,40

65,95

80,89

1

Only a 4-room apartment has one transition room Storage area in the basement is not considered 3 Only a 4-room apartment has separate storage rooms. Other flats have only built-in cupboards.

4 Some of the 2-room flats and all 3-room apartments.

5 1-room apartments in 5-storey houses have no loggias.

2

Series 1605: floor plan of two typical sections

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

Series 1-464A: floor plan of two typical sections

Series 120V: floor plan of two typical sections

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

8.2.2.3 Microclimate

CO2 concentrations, indoor air temperatures and relative air humidity during one week in a measured apartment in large concrete panel building (39)

Relation between the temperature difference (indoors-outdoors, °C, x-axis) and the air exchange n, h-1 (y-axis) (39)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

Allowed temperatures

Overheated apartments in large panel buildings

Temperature distribution in the measured apartments. X-axis – temperatures, °C; y-axis incidence (39)

Distribution of the relative air humidity values in the measured apartments. X-axis – relative humidity, %; y-axis - incidence (39)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

Thermal vision of a recently mounted plastic frame window

Condensation areas on a recently mounted plastic frame window

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

8.2.3

Technical quality

Deterioration of large panel buildings (25) (1) Building series

1605 1-464A 1-464LI 120V

Average building age during the inspection (year 1998)

Deterioration level of loadbearing elements

35,4 33,7 28,3

25 (16,4) 25-40 (19,2) 10-17 (12) 10-20

Exterior walls

Interior walls and floor slabs 10 10 10 10

Deterioration level of not loadbearing exterior elements

Total deterioration level

25-50 (31,6) 25-45 (40,5) 10-25 (16,7)

18 22,8 12,5

Right:: protruding hydro isolation layers on the wall panels joint (gable wall) Left: rendered cracks on the sand-cement render (front façade)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ 8. Appendix

Permanently closed basement windows

70% 60%

Buildings

50% 40% 30% 20% 10% 0% 40-60

60-80

80-100

100-120

120-140

140-160

160-180

real energy consumption for space heating, kWh/(m²a) 1605

1-464A-LT

1-464LI

120V

Distribution of real space heating energy consumptions of various large panel building series

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8.2.4

Economic quality

35% 30% 25% 20% 15% 10% 5% 0%

Apartment prices (2-rooms), EUR/m²

Naujamiestis (1-464A and 1605)

Žirmūnai (1-464A and 1-464LI)

Karoliniškės (1-464LI)

Šeškinė (120V)

Justiniškės (120V)

Viršuliškės (1-464LI)

2-room apartment prices in various Vilnius districts, the prevailing large panel building series is shown in brackets (35)

Šeškinė (120V) Karoliniškės (1-464LI) old

Ţirmūnai (1-464A and 1-464LI)

new

Naujamiestis (1-464A and 1605) 0

200

400

600

800

1000

1200

1400

1600

1800

2000

EUR/m²

Average 2-room apartment prices in not refurbished large panel buildings and in new construction in the same district (35)

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8.2.5

Evaluation

Location 2,00 1,500 1,00 Economic quality

,500

Sociocultural and functional quality

1605 1-464A

,00

1-464LI

120V

Ecological quality

Technical quality

Evaluation of large panel building series according to the sustainability criteria In order to sum up the results of the analysis, a simple evaluation was made. All criteria were treated equally, no influence factors were used. The following statements can be made: -

All large panel building series lack of sociocultural and functional quality. The main reasons for this are poor layout quality and monotonic, deteriorated environments.

-

The oldest large panel building series - 1605 and 1-464A are very similar. They stand in the best locations next to the city center – districts Naujamiestis and Ţirmūnai. Because of compactness, the buildings consume less energy and are easy to retrofit. Nevertheless, their appearance and functionality is very poor. Hence, strategies for a comprehensive retrofit must be found. Even a partial demolition might appear viable.

-

The middle series 1-464LI scores quite good in all analyzed categories. In contrast to the other series, it has no serious flaws. The biggest drawback is that the most of these buildings are forming monotonic and already slowly deteriorating soviet districts with rapid aging population in north-west part of Vilnius. However, these locations are quite near to the city center, have a good public infrastructure, lots of green spaces (although abandoned) and a good future potential due to the recently developing business centers nearby. What is more, some of the 1-464LI buildings stand together with 1-464A buildings in the already discussed central district Ţirmūnai, where a pilot project for a comprehensive residential quarter Retrofit is in progress.

-

Thanks to the best layouts and still not deteriorated environments, the newest series 120V (year 1978-1993) leads in the category of sociocultural and functional quality. However, these buildings are situated in quite distant and inconvenient locations. In contrast to the

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older districts, a lack of green is noticeable there. Moreover, due to the high A/AL ratio the buildings consume considerably more energy and are more costly to retrofit and maintain.

All things considered, series 1-464LI seems to have the biggest potential and demand on Retrofit.

Therefore, this series was chosen for the detailed analysis and further retrofit design.

Detailed evaluation of large panel building series Criteria

Building series 1605

1-464A

1-464LI

120V

Functional mixture

++

++

++/+

+/0

Demographic structure

+

+

+/0

++

Accessibility

++

++

++/+

+/0

Immediate proximity

0

+/0

+

+

Layouts

0

0

+

++

Barrier-free accessibility

0

0

+

0

Thermal comfort

0

0

0

0

Air quality

0

0

0

0

Simplicity of Retrofit works

++

++

+

0

Structure quality

0

0

+

++/+

Energy supply and distribution

+

+

+

+

Real heat energy consumption

++/+

++

++/+

0

Process quality

+

++

++

++

Maintenance of the building

0

0

0

0

Energy costs

+

++

+

0

Value increase potential

+

+

++

++/+

Location

Sociocultural and functional quality

Technical quality

Maintenance of the surroundings Economic quality

*Translation of evaluations into points for final comparison: 0 (bad) – 0; +/0 (satisfying or bad) – 0,5; + (satisfying) - 1,0; ++/+ (good or satisfying) - 1,5; ++ (good) - 2,0

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8.4

Energy balance

Energy balance of a building according to the EN ISO 13790:2004

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8.5

Typical retrofit projects

Type 1-464LI-18/2 (city of Alytus), Retrofit, years of construction till 1993: Floor plan (71)

Type 1-464LI-A20 (city of Šiauliai), Retrofit, years of construction 1986-1993: Floor plan (72)

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Lehrstuhl für Holzbau und Baukonstruktion Master‟s Thesis „Retrofit of Lithuanian large panel buildings with the prefabricated timber elements“ Selbständigkeitserklärung

Selbständigkeitserklärung Hiermit versichere ich, dass ich die vorliegende Arbeit selbständig verfasst und keine anderen als die angegebenen Quellen und Hilfsmittel benutzt habe.

…………………………………………………………………………………………………………………..

Dominykas Marcinonis München, 30. November 2015

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