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Sustainable Retrofitting of Office Buildings in the UK Andrea Botti Master of Science Advanced Sustainable Design School of Arts, Culture and Environment University of Edinburgh, year 2012


Acknowledgments I have been indebted in the preparation of this dissertation to Prof Remo Pedreschi who has supervised my work providing counsel, critical thinking and continuous support. I am thankful to Mr Stephen McHard for offering advice on research methodology and on the use of energy simulations. I would like to thank my dear friend Rebecca for motivating my choice to join the MSc in Advanced Sustainable Design and providing useful advice on life in Edinburgh, and my best friend Fabrizio for encouraging to follow my dreams. I owe sincere and earnest thanks to all my classmates from ASD year 2012, and particularly Hugo, for their support and the positive energy that their friendship gave me. I would like to thank my friends and flatmates Maria Giulia, Giulia and Natalie for making my stay in Edinburgh pleasant and crazily entertaining. I am thankful to the unconditional love and support that my parents Giovanni and Gabriella have shown during this year abroad as well as throughout my life.


Abstract With the Climate Change Act in 2008 the UK Government has set an ambitious legally binding target to reduce CO2 emissions by 80% by 2050, compared with a 1990 baseline. The built environment accounts for 45% of UK’s carbon emissions, with 17% attributed to non-domestic buildings. Although it is widely acknowledged that new buildings perform far better than existing ones with regards to the main environmental criteria, the annual replacement rate of existing office buildings is very modest, barely reaching 0.1%. It is crucial to find ways to reduce the emissions, running costs and overall energy consumption of existing non-domestic stock. This dissertation aims to evaluate technical opportunities and architectural consequences deriving from the retrofit of an office building in the UK, by means of two case studies. Recent research has focused on the key sources of carbon emissions for the existing building stock, identifying for every main building type different degrees of retrofitting potential. The two case studies, both prominent buildings from the 1960s, centrally located in Glasgow and Edinburgh, are representative of two main typologies: a core-dependent deep plan and a skin-dependent shallow plan. Daylight analyses are performed for both buildings. Thermal performances in both winter and summer are assessed, using current climatic data as well as future projections. In order to respond to issues related to indoor comfort conditions and poor energy performances, different levels of refurbishment are discussed and tested through energy simulations using accurate computer models. Taking the cue from previous research, retrofitting actions are grouped into four main scenarios: ‘building envelope; HVAC system; lighting systems and use of daylight, passive systems and techniques’. For every scenario the impact of macro-transformations and microsophistications on building performance is presented. The final discussion brings together commonalities and divergences in the performance of the two building typologies as well as useful information of the most appropriate interventions on each. Through the detailed insight into the case-studies, it is quite clear that the carbon impact of office building stock could be greatly reduced by means of a coherent set of retrofitting actions. Passive strategies are advocated, and their implementation is found to be effective as long as they rely on adaptive measures, providing the occupants with control over their thermal conditions.


List of abbreviations CO2

Carbon Dioxide

SCoP

Seasonal Coefficient of Performance

BCO

British Council for Offices

STA

Stabilization strategy

BMS

Building Management System

SUB

substitution strategy

BPRA

Business Premises Renovation Allowance

TRY

TEst reference Year

BRE

Building Research Establishment

UKCP09

UK Climate Projections

CCP

Climatic Potential for Ventilative Cooling

UR

Uniformity ratio

CIBSE

Chartered Institution of Building Services Engineers

CIE

International Commission on Illumination

DCLG

Department for Communities and Local Government

DF

Daylight Factor

DL

Daylight

DSF

Double Skin-Faรงade Strategy

DSY

Design Summer Year

HVAC

Heating Ventilation and Air Conditioning

IES

Illuminating Engineering Society

IES VE

Integrated Environmental Solutions Virtual Environment

IT

Information Technology

NB

Notional Building

NCM

National Calculation Methodology

NV

Natural Ventilation

PMV

Predicted Mean Vote

PPD

Predicted Percentage Dissatisfied

SCAT

Smart Controls and Thermal Comfort


Index 1. Introduction 1.1. Background to the problem��������������������������������������������������������������������������������������������������1 1.1.1. Climate change and the existing office building stock 1.1.2. Benefits and barriers to retrofit 1.1.3. Refurbishment or redevelopment of office buildings? 1.2. Purpose of the study and structure of the research������������������������������������������������������������2

2. Literature review 2.1. Building typologies����������������������������������������������������������������������������������������������������������������4 2.2. Carbon footprint of existing office spaces ��������������������������������������������������������������������������6 2.3. Retrofitting strategies and passive measures����������������������������������������������������������������������7 2.4. A holistic approach to research : the Office project ����������������������������������������������������������9

3. Research methodology 3.1. Case studies and structure of the analyses������������������������������������������������������������������������15 3.1.1. The notional building 3.2. Interview with Stephen McHard at Wallace Whittle ������������������������������������������������������16 3.2.1. Environmental modelling through computer software 3.2.2. Advantages and disadvantages of using IES 3.2.3. Sensitive parameters: infiltration 3.2.4. Sensitive parameters: occupancy 3.3. Passive measures and adaptive comfort����������������������������������������������������������������������������18 3.4. Climate data: reference years and future projections������������������������������������������������������19 3.5. Simulation parameters��������������������������������������������������������������������������������������������������������19 3.6. Retrofitting scenarios����������������������������������������������������������������������������������������������������������20


4. Case study: St Andrew’s House, Glasgow 4.1. St Andrew’s House, Glasgow����������������������������������������������������������������������������������������������22 4.1.1. Building typology 4.1.2. Existing issues 4.2. Office and hotel: occupancy and function in retrofitting ������������������������������������������������25 4.3. Analysis model ��������������������������������������������������������������������������������������������������������������������26 4.4. Winter thermal performance and annual energy consumption��������������������������������������27 4.5. Summer thermal performance ������������������������������������������������������������������������������������������28 4.5.1. Natural ventilation in exposed tall buildings 4.6. Daylight��������������������������������������������������������������������������������������������������������������������������������30 4.6.1. Daylight uniformity 4.7. Retrofitting scenarios: building envelope��������������������������������������������������������������������������32 4.7.1. Air leakage and insulation levels 4.7.2. Façade recladding 4.7.2.1. Existing external wall system 4.7.2.2. New external wall system 4.7.2.3. Air tight envelope 4.7.3. Summer solar gains 4.7.3.1. Reduce window area 4.7.3.2. Internal or mid-pane blinds 4.7.3.3. Solar control glazing 4.7.3.4. External shading devices 4.8. Retrofitting scenarios: HVAC system��������������������������������������������������������������������������������39 4.9. Retrofitting scenarios: lighting systems and use of daylight��������������������������������������������40 4.9.1. Lighting system efficiency 4.9.2. Improvement of daylight 4.9.2.1. Light shelves 4.9.3. Improvement of daylight: introducing an atrium / lightwell 4.9.3.1. Introducing an atrium in a deep plan office building


4.9.3.2. Change of layout and reduction of rentable area 4.9.3.3. Designing the atrium for daylight 4.9.3.4. Illuminance calculations 4.10. Retrofitting scenarios: passive systems and techniques ��������������������������������������������������46 4.10.1. Passive solar 4.10.1.1. External shading devices 4.10.1.2. Light shelves and shading devices 4.10.2. Implementing natural ventilation through the introduction of an atrium 4.10.2.1. Arranging the internal layout for natural ventilation and daylight

5. Case study: Argyle House, Edinburgh 5.1. Argyle House, Edinburgh ��������������������������������������������������������������������������������������������������52 5.1.1. Building typology 5.1.1.1. Existing issues: low floor height and elevated air leakage 5.1.2. Open plan and cellular office layout 5.2. Winter thermal performance and annual energy consumption��������������������������������������56 5.2.1. Open plan 5.2.2. Cellular 5.3. Daylight��������������������������������������������������������������������������������������������������������������������������������58 5.3.1. Open plan 5.3.2. Cellular 5.4. Revised annual energy consumption����������������������������������������������������������������������������������60 5.5. Summer thermal performance ������������������������������������������������������������������������������������������61 5.5.1. Open plan 5.5.2. Cellular 5.6. Summer thermal performance: future scenarios.������������������������������������������������������������63 5.6.1. Occupant density in future scenarios 5.6.2. Evaluating the impact of occupant density 5.7. Retrofitting scenarios: building envelope��������������������������������������������������������������������������67


5.7.1. Summer solar gains 5.7.1.1. Reduce windows area 5.7.1.2. Internal or mid-pane blinds 5.7.2. Air leakage and insulation levels 5.7.3. Façade removal and recladding 5.8. Retrofitting scenarios: HVAC system��������������������������������������������������������������������������������69 5.9. Retrofitting scenarios: lighting systems and use of daylight��������������������������������������������70 5.9.1. Lighting system efficiency 5.9.2. Improvement of daylight 5.9.2.1. Light shelves 5.9.2.2. Internal office layout and access to daylight 5.10. Retrofitting scenarios: passive systems and techniques ��������������������������������������������������72 5.10.1. Passive solar 5.10.2. Thermal mass 5.10.2.1. Exposing thermal mass 5.10.2.2. Introducing night ventilation 5.10.2.3. Effects of thermal mass and night ventilation 5.10.3. Implement forms of natural ventilation, adapting the internal office layout 5.10.3.1. Existing north and south elevation 5.10.3.2. Proposed north elevation 5.10.3.3. Proposed south elevation


6. Conclusions 6.1. Research objectives��������������������������������������������������������������������������������������������������������������81 6.2. Summary of findings ����������������������������������������������������������������������������������������������������������81 6.2.1. Building typology 6.2.2. Occupant density and office technology 6.2.3. Change of use 6.2.4. Passive measures and comfort in a future climate scenario 6.3. Limitations of the present study and further research����������������������������������������������������84

Appendices APPENDIX A..Input parameters for energy simulations with IES �������������������������������������������� I APPENDIX B.. . Max Fordham sustainability matrices����������������������������������������������������������VII APPENDIX C.. . . . . . . . . . . . . . . . . . St Andrew’s House�������������������������������������������������������������X APPENDIX D.. . . . . . . . . . . . . . . . . . . . . . Argyle House���������������������������������������������������������� XV


List of tables and figures Table 1.  Annual emissions (kgCO2/m2) for office buildings (van de Wetering and Wyatt, 2010)6 Table 2.  Natural and low ventilation measures to be incorporated at four levels of refurbishment (BRE, 2000).8 Table 3.  Classification of buildings for investigations on their energy-related behaviour (adapted from Dascalaki and Santamouris, 2002).10 Table 4.  Template table for the parameters used in the environmental simulations

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Table 5.  Retrofitting actions and scenarios. Different colours (from light yellow to orange) indicate incremental level of retrofitting.

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Table 6.  Characteristics for type A buildings (adapted from Dascalaki and Santamouris, 2002).23 Table 7.  Simulation parameters for baseline situation (see APPENDIX A for details)

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Table 8.  Annual energy consumption for St Andrew’s House - baseline scenario

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Table 9.  Simulation parameters for baseline situation (see APPENDIX A for details)

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Table 10.  Summer indoor air temperatures over 25°C and 28°C during occupied hours.

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Table 11.  Illuminance Categories and Lux Ranges (Kaufman, Christensen and IES, 1987)30 Table 12.  Required minimum daylight factors, grouped by latitude (DeKay, 2010).30 Table 13.  Daylight calculation results for typical floor

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Table 14.  Simulation parameters for building envelope scenario (see APPENDIX A for details)

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Table 15.  Simulation parameters for building envelope scenario, with improved airtightness (see APPENDIX A for details) 35 Table 16.  Thermal energy consumptions and emissions for three retrofitting scenarios

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Table 17.  DF and atria proportions required under overcast sky, listed by latitude (DeKay, 2010).41 Table 18.  Default surface properties for atrium daylight analysis

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Table 19.  Updated surface properties for atrium daylight analysis

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Table 20.  Characteristics for type C buildings (adapted from Dascalaki and Santamouris, 2002).53 Table 21.  Simulation parameters for evaluating the baseline thermal performance (see APPENDIX A for details) 56


Table 22.  Annual energy consumption for St Andrew’s House - baseline scenario

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Table 23.  Annual energy consumption for Argyle House - baseline scenario

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Table 24.  Daylight calculation results for the open plan areas typical floor

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Table 25.  Daylight calculations for some cellular offices on typical floor. The cellular structure is the reason for a better DL uniformity. 59 Table 26.  Simulation parameters for evaluating the baseline thermal performance (see APPENDIX A for details) 60 Table 27.  Revised annual energy consumption for Argyle House - baseline scenario

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Table 28.  Predicted Mean Vote (PMV) for the month of July

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Table 29.  Simulation parameters for baseline situation

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Table 30.  Simulation parameters for future climate projections (see APPENDIX A for details)

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Table 31.  Summer indoor air temperatures for different simulations - climate data

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Table 32.  Baseline internal gains parameters

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Table 33.  Simulation parameters for increased occupant density (see APPENDIX A for details)

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Table 34.  Simulation parameters for evaluating the HVAC scenario (see APPENDIX A for details)69 Table 35.  Annual energy consumption for Argyle House - HVAC scenario compared to baseline 69 Table 36.  Simulation parameters for suspended ceilings (above) and exposed concrete ceilings 72 (below) (see APPENDIX A for details) Table 37.  Parameters for iterative testing on thermal mass and night ventilation (see APPENDIX A for details) 73


Figure 1.  Ecopoints and whole life costs per m2 for various options (adapted from Anderson and Mills, 2002:p6).2 Figure 2.  Taylorist office

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Figure 3.  Bürolandschaft

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Figure 4.  Typical office building types in the UK (BRE, 2000)5 Figure 5.  Map of mean climatic cooling potential (Kh/night) in July (Artmann, Manz and Heiselberg, 2007) 7 Figure 6.  Shearing layers of change (Brand, 1994)8 Figure 7.  Energy use breakdown for type A (adapted from Dascalaki & Santamouris, 2002)10 Figure 8.  Energy use breakdown for type B (adapted from Dascalaki and Santamouris, 2002)11 Figure 9.  Energy use breakdown for type C (adapted from Dascalaki and Santamouris, 2002)11 Figure 10.  Energy use breakdown for type D (adapted from Dascalaki and Santamouris, 2002)11 Figure 11.  Energy use breakdown for type E (adapted from Dascalaki and Santamouris, 2002)12 Figure 12.  Energy consumption of five building types according to the climatic region (adapted from Dascalaki and Santamouris, 2002)12 Figure 13.  Retrofitting scenarios for type A (adapted from Dascalaki & Santamouris, 2002)13 Figure 14.  Retrofitting scenarios for type C (adapted from Dascalaki and Santamouris, 2002)13 Figure 15.  The two case studies: St Andrew’s House, Glasgow (right) and Argyle House, Edinburgh (left)

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Figure 16.  Comfort temperatures for buildings in free-running mode (continuous line) and heated or cooled mode (dashed line) (Nicol and Humphreys, 2007)18 Figure 17.  Comfort zones for buildings in free-running mode (continuous line) and heated or cooled mode (dashed line) (Nicol and Humphreys, 2007)18 Figure 18.  Changes to the average daily mean temperature by the 2080s, under the Medium emissions scenario (Jenkins, 2009).19 Figure 20.  Street view of St Andrew House (Urquhart, 2010)22 Figure 19.  Bird-eye view (adapted from Microsoft, 2012b)22 Figure 21.  Location plan (adapted from Glasgow City Council, 2009).22


Figure 22.  Typical plan zoning for a deep plan office building (BRE, 2000)23 Figure 23.  St Andrew’s House - typical floor plan (Swift and Partners, 1961). Internal partitions are here not represented. 23 Figure 24.  St Andrew’s House - typical floor plan (Glasgow City Council, 2009)23 Figure 26.  Cross section on lavatories (Swift and Partners, 1961)24 Figure 27.  Existing cladding (Glasgow City Council, 2007)24 Figure 28.  Safety cranes (highlighted) were installed to arrest falling masonry (adapted from Glasgow City Council, 2007)24

Figure 25.  Cross section on stairs (Swift and Partners, 1961)24 Figure 29.  Architectural rendering of refurbishment project (Glasgow City Council, 2009)25 Figure 30.  Existing floor plan for typical floor (Glasgow City Council, 2009)25 Figure 31.  Proposed floor plan for typical floor (Glasgow City Council, 2009)25 Figure 33.  Existing floor plans (Glasgow City Council, 2009)26 Figure 32.  SketchUp model of cellular layout

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Figure 35.  Energy consumption for Argyle House in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)27 Figure 34.  Annual energy consumption for St Andrew’s House - baseline scenario 

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Figure 36.  Summer air temperatures for all the office rooms (different colours). Dry-bulb outdoor air temperature in light green.

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Figure 37.  Sources of heat during summer (Rennie and Parand, 1998) 

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Figure 38.  On a windy day (30th July) the conspicuous volume of external ventilation (blue) is the main reason for the divergence between air temperature (green) and dry resultant temperature (grey). That results in a high PPD value (red). 29 Figure 39.  Volume flows of incoming air (blue) for a room facing south-east on a windy day. 29 Figure 40.  Daylight factor for typical floor

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Figure 41.  Areas below 300 lux for typical (green)

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Figure 42.  Estimating maximum room depth for daylight uniformity (Brown and DeKay, 2000)31 Figure 43.  Uniformity ratios

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Figure 44.  Existing PC panels (Glasgow City Council, 2009)32 Figure 47.  Removal operations in St Andrew’s House (Urquhart, 2011)32 Figure 45.  Section on external cladding (Swift and Partners, 1961)32 Figure 46.  Creating a database for the existing fabric in IES Apache database (see APPENDIX A for details)32 Figure 50.  Adding the new construction in IES Apache database for new energy simulation

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Figure 48.  Dry-wall construction basic scheme (Knauf, 2012)33 Figure 49.  Types of new wall constructions (adapted from Knauf, 2012)33 Figure 53.  Heat gains and losses over a week-time in winter

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Figure 51.  Daily heat gains and losses for existing (orange) and replaced (brown) external walls, in comparison to glazing (blue) 34 Figure 52.  Daily heat gains and losses for existing (blue) and replaced glazing (cyan)

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Figure 54.  Heating loads in comparison for the whole month of January: XUV (red), NUV (orange) and NUV tight (yellow).

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Figure 55.  Enlarged view of Figure 54, showing the heating loads for the first week of January35 Figure 56.  Thermal energy consumptions and emissions for three retrofitting scenarios

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Figure 57.  South elevation enlarged to assess the glazing ratio (adapted from Glasgow City Council, 2009)37 Figure 58.  South elevation on Sauchiehall Street (Glasgow City Council, 2009)37 Figure 60.  Interior view of the offices in St Andrew’s House: internal blinds are installed (Glasgow City Council, 2007)38 Figure 59.  Shading types: internal blinds (top left and bottom left), mid-pane blinds (top right), 38 external louvres (bottom right) (adapted from Rennie and Parand, 1998)  Figure 61.  External shading types (adapted from CIBSE, 2004)39 Figure 62.  Impact of a light shelf on illumination levels (adapted from Rennie and Parand, 1998).40 Figure 63.  Effects of external and internal light shelves (above) and distribution of light with different angles (below) (ibid)40 Figure 64.  Suggested dimensions for light shelf in UK (ibid)40


Figure 65.  Sizing atria for daylight in adjacent rooms (Brown and DeKay, 2000).41 Figure 66.  Existing floor plan - central services core and cellular offices along a ring corridor. 42 Figure 67.  Proposed floor plan - central atrium with open plan office space and services pushed against the north façade. 42 Figure 69.  Central atrium - perspective of the analysis model

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Figure 68.  Central atrium - perspective section

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Figure 72.  Different case highlight how reflections from the atrium surfaces affect daylight distribution (Rennie and Parand, 1998).43 Figure 70.  Wireframe cross section of the atrium. The glazing ratio has constant value of 50% throughout the total height. 43 Figure 71.  Wireframe cross section. The glazing ratio is progressively reduced bottom-up.

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Figure 73.  Atrium daylight illuminance for default surface properties

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Figure 74.  Atrium daylight illuminance for default surface properties

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Figure 75.  Insolation analysis, 21st December

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Figure 76.  Shading on south façade, 21st December

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Figure 78.  Insolation analysis, 21st June

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Figure 77.  Shading on south façade, 21st June

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Figure 79.  Solar gain (yellow) and air temperature (green) for different rooms on summer day (28th July) 47 Figure 80.  Solar gain comparison between baseline conditions (orange) and with new external shading devices (yellow) for different rooms on summer day (28th July) 47 Figure 83.  Close-up view of shading devices for typical floor

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Figure 81.  Suggested dimensions for light shelf in UK (Rennie and Parand, 1998)48 Figure 82.  Shading devices for typical floor

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Figure 84.  Cross section showing the existing scenario: single-side ventilation

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Figure 85.  Cross section showing the existing scenario: natural ventilation is enhanced by the stack effect introduced by the atrium 49 Figure 86.  Floor plan is arranged to optimise natural ventilation and access to natural light 

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Figure 89.  Site plan with indication of the building’s parts (adapted from Swift and Partners, 1961)52 Figure 87.  Bird-eye view (adapted from Microsoft, 2012a)52 Figure 88.  Location plan (adapted from Edinburgh City Council, 2010)52 Figure 90.  Average sizes and plan structures for buildings from Type 1 (above) and Type 2 (below) (adapted from BRE, 2000)53 Figure 91.  Floor F (Level 1) plan (adapted from Laird, 1966)53 Figure 92.  Cross section (adapted from Laird, 1966)54 Figure 93.  Cross section (Laird, 1966)54 Figure 94.  Enlarged view of the cross section showing the height of a typical floor (adapted from Laird, 1966)54 Figure 95.  Detail of the existing cladding system (Laird, 1966)54 Figure 96.  SketchUp model of first scenario: open plan layout for typical floor

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Figure 97.  SketchUp model of second scenario: cellular layout for typical floor

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Figure 99.  Annual energy consumption for St Andrew’s House - baseline scenario 

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Figure 98.  First scenario modelled in IES SketchUp plugin. The room under focus (room 14) is highlighted in red. 56 Figure 100.  Heating plant sensible load for baseline situation

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Figure 101.  External solar gains and conduction losses for room 14

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Figure 102.  Annual thermal energy consumption breakdown

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Figure 104.  Energy consumption for Argyle House in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)57 Figure 103.  Second scenario modelled in IES SketchUp plugin. The rooms facing south are highlighted in red.

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Figure 106.  Area below the threshold value of 300 lux

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Figure 105.  Filled contour daylight factor for typical floor

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Figure 107.  Filled contour daylight factor for typical floor

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Figure 108.  Energy consumption for Argyle House as result of adjusted parameters, in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)60


Figure 109.  Summer air temperature for room016 in Block A (dark green), outside dry-bulb temperature (green/cyan)

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Figure 110.  Causes of summer discomfort for a workplace: pollution from equipment, smoking and direct solar radiation on occupants (adapted from Rennie and Parand, 1998)61 Figure 111.  Solar gains in comparison: north-facing office (yellow) and south-facing one (red)62 Figure 112.  Air temperatures in comparison: summer temperature in south-facing cellular offices (red), north-facing cellular offices (green) and open plan (yellow). Dry-bulb outside air temperature in cyan. 62 Figure 113.  Summer dry-bulb outdoor air temperatures for simulations B2.02 (green) and B2.03 (red) in comparison 63 Figure 114.  Tested rooms at floor K (level 4)

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Figure 115.  Floor K plan _ scale 1:50 (adapted from Argyle House, 2011)64 Figure 116.  Workplace redevelopment renderings (Argyle House, 2011)64 Figure 117.  Incidental heat gains in comparison

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Figure 118.  CO2 concentrations for increased occupant densities

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Figure 119.  Summer air temperatures for increased occupant densities on a weekly basis

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Figure 120.  Summer air temperatures for increased occupant densities on a daily basis

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Figure 121.  Argyle House, north-west elevation (Parnell, 2011b)67 Figure 122.  Floor plan (adapted from Laird, 1966)67 Figure 124.  Detailed section of the existing façade, showing the cladding system (Laird, 1966)68 Figure 123.  Zoomed elevation for visual analysis of the cladding system (adapted from Parnell, 2011a).68 Figure 125.  Axonometric exploded of the existing cladding system.

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Figure 126.  Block A, Floor F plan _ existing layout. The area below 300 lux is hatched in green. 71 Figure 127.  Block A, Floor F plan _ proposed layout (adapted from Argyle House, 2011).71 Figure 128.  Air temperatures (red and green) and ceiling conduction gains (yellow and pink) for suspended ceilings (FC) and exposed concrete ceilings (XC) in comparison. Infiltration in blue. 72


Figure 129.  FC _ Existing ceiling/floor layers

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Figure 130.  XC _ Exposed concrete ceiling

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Figure 131.  XCI _ Exposed concrete ceiling with underfloor insulation

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Figure 133.  Ceilings and floor conduction gains for 20th July. XC and XCI ceilings (red and pink); XC and XCI floors (blue and cyan) 74 Figure 132.  Ceiling conduction gains in comparison for working week 17th-21st July: XC without night ventilation (blue), XCI with night ventilation (red) and XTCI with night ventilation (pink)74 Figure 134.  Floor F plan _ cross ventilation on existing layout

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Figure 135.  Floor F plan _ cross ventilation strategies implemented for the proposed layout. Corridors for NV are hatched in orange.

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Figure 138.  Implemented NV strategies with new corridor window

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Figure 136.  NV with existing window

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Figure 137.  Implemented NV strategies with new typical window

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1. Introduction


1.1. Background to the problem

1.1.2. Benefits and barriers to retrofit

1.1.1. Climate change and the existing office building stock

This research shows that carbon footprint reduction is one key reason for retrofitting an office building. The re-use of an existing building’s fabric retains a fair amount of the energy embodied in the original construction. This varies greatly with the degree of refurbishment, which can range from the replacement of external windows to a complete recladding or major alterations in the structure of the floor plan (e.g. by moving service cores). Moreover, the improvement of services and building performance results in reduced overall environmental impact, as this research will later demonstrate.

With the Climate Change Act in 2008 the UK Government introduced the world’s first long-term legally binding framework to address the dangers of climate change. The ambitious targets comprise a 80% CO2 emissions reduction by 2050, compared with a 1990 baseline (Great Britain. Climate Change Act 2008). It has been estimated that 45% of the UK’s total carbon emission derive from building, 17% of which from non-domestic buildings (Department for Communities and Local Government, 2009). Annual replacement rates in the UK have been estimated to be very modest at circa 0.1% of the existing building stock. Considering the very low demolition rates, renovation and refurbishments of commercial buildings are expected to reach between 2 and 8% of the existing stock, depending on sectors (Hartless, 2004). At this rate, 70% of today’s building stock is expected to be still in use in 2050; furthermore, 40% of it will be pre-1985. As a consequence it is indisputable that the national targets will only be met by improving the energy performance of existing buildings. This is particularly the case for the current economic circumstances, when fewer office buildings are commissioned and built.

Introduction

However several economic benefits have been identified by main market players, to justify the choice of refurbishment over a complete redevelopment for office buildings (Addy and McCallum, 2012): • a better balance of risk and return; • quick delivery back to market; • lower construction times and costs: depending on the level of retrofit, office retrofit can be from 10 to 75% quicker and cheaper than new build; • maximised value of an existing asset and retaining useful attributes of the original building (e.g. car parking allocation and permitted development density and massing).

found in the UK commercial property market, that prevent owners and developers from investing in retrofits (Rhoads, 2010): • A lack of access and availability of capital funds. • Poor provision of viable business cases for uptaking retrofit interventions. The issue of ‘split incentive’, whereby the owner absorbs most of the costs while the occupiers benefit from energy savings, thus having no incentive for energy conservation. • Unclear criteria and processes for assigning and evaluating the responsibilities of those carrying out the retrofitting interventions. • A lack of appropriate technological knowledge about possibilities, issues and constraints associated with specific retrofit actions. Endemic skills shortage in the built environment sector. • Insufficient focus from policy makers on current building stock, as compared to new build. However the introduction in 2005 of the Business Premises Renovation Allowance has set the trend to change. It gives an initial allowance covering in full the expenditure on converting or renovating unused business premises in a disadvantaged area, serving as a strong economic incentive to bring old properties back into use.

On the other hand, some key barriers were

1


1.1.3. Refurbishment or redevelopment of office buildings? Research carried out by the Building Research Establishment (Anderson and Mills, 2002) demonstrated that refurbishment solutions have lower environmental impact and whole life costs than analogous redevelopment solutions, when using the same method of ventilation or cooling. Embodied energy retained in construction plays a significant role within the study, accounting for 40-50% of the total environmental impact of a redevelopment. Comparative analyses also showed that naturally ventilated solutions have a lower impact per m2 than analogous air conditioned solutions (ibid). As a result, the additional impact of a redeveloped office over a total refurbishment was found to be 13-14% for an air conditioned office and approximately 20% for a naturally ventilated one (Figure 1).

1.2. Purpose of the study and structure of the research The aim of this dissertation is to evaluate the technical opportunities and architectural consequences of retrofitting an office building in the UK. The second chapter is dedicated to a literature of the subject from a range of perspectives. Some sources present an overview of the existing stock of office buildings in the UK, providing outlines of the main building types in terms of architectural typology and carbon footprint.

In the final chapter, results are discussed. Final reflections regard the scope, ambitions and limitations of the present study, in order to contribute to the definition of a valid modus operandi, which could guide design choices when retrofitting in similar scenarios.

Research from the Office project investigated European office building stock and presented energy performance results for five main building types in four different European climatic regions. These results pave the way for determining the potential of retrofitting scenarios, which are tested and presented in a comparative manner. Chapters 4 and 5 are the core of the thesis, presenting two case studies: two iconic and somehow tired buildings, St Andrew House in Glasgow and Argyle House in Edinburgh, both centrally located and in need of refurbishment. Environmental analyses are performed in the first instance to assess baseline conditions and the buildings’ retrofitting potential, and secondly to test the effectiveness of proposed retrofitting strategies. Since the two buildings

Introduction

are representative of common typologies of offices in the UK, the research will use them as tests, highlighting issues and aspects of broad validity.

Figure 1.  Ecopoints and whole life costs per m2 for various options (adapted from Anderson and Mills, 2002:p6). Note: 100 ecopoints = environmental impact of one person in the UK over one year.

2


2. Literature review


2.1. Building typologies In “Typological [r]evolution of the workplace” Philip Vivian (2012) traces the evolutionary journey that throughout the twentieth century has reflected social, economical and technological spirits of the time.

The Taylorist office During the early 20th century the ‘scientific management’ of the workplace was introduced, under the influence of Taylorism, a management theory aimed at maximising efficiency and oversight for working procedures in the factory. Taylorist principles included splitting tasks into specific and repetitive acts, to be executed by clerical workers under close supervision by managers. As a result the workplace was organised hierarchically to separate people and functions and reinforce status. Architectural typology was heavily influenced by technological ‘constraints’: plans were narrow to access natural light and allow for limited structural spans. Offices were distributed along double-loaded corridors and desks serially repeated in open plan areas (Figure 3).

Corporatisation of the workplace During the post-World War II period workplaces started to accommodate spaces focused on providing workers with comfort, in order to increase the staff’s motivation and productivity. While the separation of managers and clerks continued, work started

Literature review

to be organised into groups and glass partitions were introduced to allow uninterrupted visual contact. Technological advances, such as airconditioning and fluorescent lighting, set the office space progressively more independent from the outdoor environment. Floor could be open and deep, and receive uniform energy, light and air by the means of the newly introduced suspended ceilings.

Figure 2.  Taylorist office

Figure 3.  Bürolandschaft

Bürolandschaft The management theory called Bürolandschaft (“office landscape”) was predominant during the 1960s. The theory focused on promoting communication between workers and eradicating the concepts of hierarchy and status. Office layouts became totally open plan, with furniture almost disseminated in large continuous spaces (Figure 3). Cores were either distributed across the floor plate or located in the margins to avoid obstructions. Floor plates increased in depth and the internal environment was fully controlled by mechanical means.

The professionalisation of the workplace Towards the end of the 20th century corporate headquarters gave way to the surge of smaller consulting firms and the proliferation of speculative office buildings. Floor plates were more shallow to maximise the perimeter and fairly consistent in depth from core to perimeter walls. Technological development allowed floor area to be free from structural elements while

the introduction of raised floors paved the way for a greater flexibility of services, helping the development of workstation layouts.

The humanisation of the workplace The rapid breakthrough of IT has in recent years progressively demolished the conventions of the traditional office. Hierarchy and separation have been greatly reduced in favour of flexible, social and interactive spaces to encourage communication and teamwork. Environmental criteria have been increasingly influencing design, with technological developments affecting the performance of services, building skin and renewable energy (e.g. chilled beams, selective glass, photovoltaic). Some aspects such as the Bürolandschaft’s floor plate flexibility and the side core typology of postWorld War II have received renewed appraisal. 4


The reports “Comfort without air conditioning in refurbished offices_ an assessment of possibilities” (BRE, 2000) and “Energy use in offices” (Action Energy, 2003) are intended to inform about potential improvements in the energy and environmental performance of existing office buildings. Four main building types are identified in the UK:

Type 1: Naturally ventilated, cellular A simple shallow-plan building, often relatively small and sometimes in converted residential accommodation. The typical size ranges from 100 to 3000 m2, while building depth is comprised between 10 and 20 metres. It has a domestic approach, with individual windows, lower illuminance levels, local light switches and heating controls. Occupants can exercise a

high level of control over the building according to their needs; as a consequence energy consumption, electricity in particular, is lower.

Type 2: Naturally ventilated, open plan Often purpose-built, it is largely open-plan, with some cellular offices and special areas. The typical size ranges from 500 m2 to 4000 m2. Illuminance levels and hours of use are often higher than in cellular offices. Office equipment is also in greater demand and more frequently used. As a result of the higher number of occupants, lights and shared equipment are generally switched in larger groups, and stay on for longer.

Type 3: Air-conditioned, standard Typical size ranges from 2000 to 8000 m2. Occupancy and planning are similar to type 2, but floor plan is usually deeper; often windows are tinted or shaded, further reducing daylight. Buildings of this type are often more intensively used.

Type 4: Air-conditioned, prestige National or regional head office, or administrative centres. The typical size goes from 4000 to 20000 m2. This type is often purpose-built or refurbished to high standards. Plant is run for longer hours to suit a much more diverse occupancy. Office equipment includes catering kitchens, air-conditioned rooms for mainframe computers and communication equipment.

Figure 4.  Typical office building types in the UK (BRE, 2000) Type 1

Literature review

Type 2

Type 3

Type 4

5


2.2. Carbon footprint of existing office spaces In “Measuring the carbon footprint of existing office space” van de Wetering and Wyatt (2010) identify building operation and commuting as the two main sources of office-related CO2 emissions. Existing buildings present a different set of challenges if compared to new developments, due to embodied energy in the existing structure and fixed location in relation to public transport. The paper evaluates current assessment instruments as well as voluntary methods. It argues that the most preferred tools on the market are based on qualitative information and they estimate theoretical performance rather than measuring actual emissions (deriving from building operation and travel). As a result they underestimate the actual performance of UK office building stock. The research shows how poorly the existing office stock performs with regards to CO2 emissions (Table 1). There is a significant difference between air-conditioned and naturally ventilated offices. Standard airconditioned spaces are responsible for more than twice the CO2 emissions of naturally ventilated offices; prestige air-conditioned more than three times as much.

existing office space in the UK can be found in the surge of office specifications during the late 1970s - early 1980s, which relied increasingly on the use of air-conditioning and electrical systems, combined with out-of-town located workplaces, almost entirely reliant on car-based transport. Those have been identified by the authors as the two main carbon emission issues to be addressed. As for the latter (i.e. workrelated transport) their research, based on a case study research in the city of Bristol, concludes that the more sustainable solution is proximity to public transport nodes. The authors insist that to achieve the cuts in CO2 emissions the government has legally committed to, the priority is to ‘decarbonise’ the existing office building stock.

Table 1.  Annual emissions (kgCO2/m2) for office buildings (van de Wetering and Wyatt, 2010)

The reasons for the very poor performance of

Literature review

6


2.3. Retrofitting strategies and passive measures In his paper “Office building retrofitting strategies: multicriteria approach of an architectural and technical issue” Rey (2004) introduces the “inclusive” notion of retrofitting strategy as the set of interventions “dictated by a coherent architectural attitude and technically optimised”. He observes that interventions on the original façade are a prominent area of refurbishment as they are closely linked to technical installation.

In “Cooling strategies, summer comfort and energy performance of a rehabilitated passive standard office building” Eicker (2010) acknowledges that office buildings in Europe have on average very high primary energy consumption, corresponding to several hundred kWh/m2 per year, mostly due to heating in moderate European climates. However in recent times air-conditioning and new technologies have made electricity consumption play an increasingly bigger role in total consumption.

Eicker presents performance results of an office building in Tübingen, Germany, which was one He points out three different types of retrofitting of the first to be retrofitted to passive energy strategy, which involve a progressively higher standards. To meet the strict requirements, metamorphosis of the building’s appearance: high-technology strategies were employed, • stabilization strategy (STA); such as the upgrade of the building skin to • substitution strategy (SUB); accommodate very high insulation and the • double skin-façade strategy (DSF). use of phase change materials to increase the Rey’s contribution is remarkable for heat storage capacity in ceilings and walls. developing an assessment methodology Mechanical ventilation systems with heat which simultaneously takes into account recovery were introduced; a combined use of environmental, sociocultural and economic a ground heat exchanger and night ventilation criteria. Although retrofitting strategies are provided summer cooling. indeed affected by many parameters, the An interesting point is made by Artmann, Manz application of his method to a few case and Heiselberg in the paper “Climatic potential studies confirms the initial hypothesis that for passive cooling of buildings by night-time the classification of strategies really depends upon a number of identified factors (e.g. age of vent. in Europe” (2007). The authors remark that over the last few decades the overall buildings). trend in most of Europe has been a reduction in heating demand and a concurrent surge in

Literature review

cooling demand. They consider passive cooling a promising technique, especially in moderate or cold climates of Central and Northern Europe. They define the mean climatic potential for ventilative cooling (CCP) as a summation of products between building/external air temperature-difference and time interval. An overview of the climatic potential for night-time cooling in Europe, expressed by means of a map (Figure 5), shows how Northern European countries can benefit from a high cooling potential of 120–180 Kh even in the hottest months of the year.

Figure 5.  Map of mean climatic cooling potential (Kh/night) in July (Artmann, Manz and Heiselberg, 2007)

7


The report “Comfort without air conditioning in refurbished offices_ an assessment of possibilities” (BRE, 2000) summarises the results of studies aimed to investigate whether a number of key design principles could be successfully applied to the retrofit of any office building in the UK. Four levels of refurbishment are examined, as well as sets of energy efficiency measures to achieve natural or low-energy ventilation strategies (Table 2).

measures should be arranged to minimise the internal gains, reduce the heat stored into the building’s fabric and enhance the flow of cool air through the rooms both at daytime and at night time. It has been estimated that shallow offices can benefit from natural ventilation solutions with very short payback periods, under five years, while deep-plan offices need longer periods. For the latter cost-effective and low-energy hybrid ventilation solutions exist.

Level 1 is a minor refurbishment. It involves measures such as: additional opening windows, reduced window area, internal blinds, lowenergy IT solutions, redesigned office layout to maximise access to daylight.

With reference to the concept of shearing layers presented by Steward Brand (1994), it can be observed that the retrofit measures listed in Table 2 are progressively intrusive, affecting Figure 6.  Shearing layers of change (Brand, 1994) different layers. Measures from Level 1 regard

mostly Space Plan and Skin, while Levels 2 and 3 also involve changes to Services. Finally measures from Level 4 go so far as to cause alterations to Structure (Figure 6).

Level 2 is an intermediate refurbishment. It Table 2.  Natural and low ventilation measures to be incorporated at four levels of refurbishment (BRE, 2000). involves: mid-pane blinds for solar control; new Refurbishment measures - options at each level Level 1 Level 2 Level 3 Level 4 energy-efficient lighting and control system; removal of false ceilings to expose thermal Layout of workstations and office equipment near extract √ √ √ √ Choice of low-energy office equipment on replacement √ √ √ √ mass and raise ceiling height, providing the Replace opening windows with multiple openings √ √ √ √ possibility of night cooling. Level 3 is a major refurbishment, involving solar control, the use of stair cores as ventilation stacks and BMS controlled night cooling. Level 4 is a complete refurbishment. It essentially involves major structural alterations in order to obtain radical changes to air flow paths, e.g. by the addition of central atrium or double façade to drive stack ventilation. The authors observe that, with the introduction of a low-energy ventilation strategy, the retrofit Literature review

Reduce window area Good daylighting from positioning of windows Some solar control by glazing choice and internal blinds Reduction of unwanted infiltration Efficient electric lighting systems and controls Removal of suspended ceiling Night cooling by leaving windows open - manual control Added solar control by use of mid-pane blinds Controllable windows or vents, perhaps by the BMS Use of stair wells or service shafts for stack ventilation Added solar control by use of external blinds Use of double façade or solar chimney to act as a ventilation stack Introduction of an atrium in a deep-plan building

√ √ √ √

√ √ √ √ √ √ √ √

√ √ √ √ √ √ √ √ √ √ √

√ √ √ √ √ √ √ √ √ √ √ √ √

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2.4. A holistic approach to research : the Office project

have looked at passive systems with scepticism, expressing concerns about a number of related aspects, such as: It has been estimated that all office buildings • the absence of any form of rental premium undergo retrofitting, at different levels, at that passive buildings could benefit from; least a couple of times during their lifetime • risks to thermal comfort, particularly (Santamouris and Hestnes, 2002). Over a period with high levels of occupancy and intensive of 50 years, major changes occur on average equipment use; three times in services and up to ten times in • a certain lack of flexibility in accommodating space plan. As a result the cumulative cost of ever changing layouts, according to a wide ameliorations can be as high as three times the range of occupiers needs. cost of the original building. • the use of technologies that are seen as In the paper “Office - passive retrofitting unfamiliar and essentially require a change of of office buildings to improve their energy habits from the building’s management and its performance and indoor working conditions” occupants; (ibid) the authors identify a number of key The OFFICE research programme was large reasons for retrofitting: and ambitious in scope. It aimed to develop • degradation of the building’s fabric and global retrofitting strategies, as well as tools technical equipment; and guidelines in order to advocate for the • application and use of new technologies and successful and cost-effective employment of new equipment; passive solar and energy efficiency retrofitting • adaptation to new standards. measures to office buildings. The authors rightfully envisage an opportunity The project involved a set of research actions, for substantial improvement of energy specifically aimed at combining scientific performance in every refurbishment even when, and technical knowledge with best practice as is often the case, environmental criteria are architecture; develop performance criteria, not the main drivers for retrofit. tools for retrofitting and rating methodologies; Retrofitting interventions, authors say, have carry out pre-normative research, and integrate hitherto almost completely disregarded the results into both a set of guidelines and an measures related to passive solar heating, assessment methodology for retrofitting office daylighting and passive cooling of buildings. buildings in Europe. The industry players developers and investors Literature review

9


The paper “On the potential of retrofitting scenarios for offices” (Dascalaki and Santamouris, 2002) sums up the research, carried out within the framework of Office research project, aimed to assess the energy conservation potential of integrated retrofitting actions for five building types in four different climatic regions in Europe.

Type A

Ten different buildings were investigated in terms of energy performance. They were first classified into four different types, according to criteria such as degree of exposure, thermal mass, skin dependence and internal structure.

This type was found to have the highest total annual energy consumption of all the building types, under all climatic conditions. This is why the authors identify in this type a strong potential for energy reduction.

Computer models were accurately developed for each building. The impact of different climatic scenarios on retrofitting measures was evaluated by means of simulation, run using meteorological data from ten European locations, representative of the four main climatic regions in Europe: Southern Mediterranean, Continental, Mid-Coastal and North-Coastal.

This type features a high ratio between volume and envelope surface, a generally open plan internal layout, massive floor and ceilings and large perimeter glazed areas. The operating hours are high and so is the installed power for lighting. The building’s loads are met using a central HVAC system with constant set-point.

cooling; 10% heating; 51%

lighting; 39%

%

reasons for consumption

Heating

51

ventilation and heat losses through fabric

Lighting

39

deep plan prevents from having a satisfactory daylight penetration

Cooling

10

Table 3.  Classification of buildings for investigations on their energy-related behaviour (adapted from Dascalaki and Santamouris, 2002).

degree of exposure Free standing Type A

X

Type D

X

thermal mass heavy

light

skin dependence

internal structure

Skin dep.

Core dep.

Open plan

X

X

X X

Type C Type E

enclosed

X

Type B

Literature review

Figure 7.  Energy use breakdown for type A (adapted from Dascalaki & Santamouris, 2002)

X

cellular

X

X

X

X

X

X

X

X

X

X

X X

10


Type B

Type C

Type D

Buildings of this type are located in a dense urban environment and they are quite protected by adjacent buildings. The outer skin is well insulated and windows are double-glazed. The interior structure comprises mostly small rooms distributed along corridors. As for the previous type, the buildings are equipped with a central HVAC system with constant set-point.

Although their characteristics are similar to the previous type, they are more exposed to outdoor environment. Hence their outer skin plays a bigger role in the overall energy performance. They have heavy/concrete floors and ceilings. The cellular structure, made of partitions and small spaces, is such that daylight penetration is satisfactory. That allows the building to have a very modest installed power for artificial lighting (Figure 9).

These buildings have little shading from the surroundings, if any at all. Due to their extensively glazed façades they suffer from high direct solar gains, that add to cooling loads (Figure 10). The internal structure is generally open plan; thermal mass is not effective because of the presence of false ceilings.

Figure 9.  Energy use breakdown for type C (adapted from Dascalaki and Santamouris, 2002)

Figure 10.  Energy use breakdown for type D (adapted from Dascalaki and Santamouris, 2002)

The overall energy consumption is considerably lower than the previous type, and can be broke down as in Figure 8.

Figure 8.  Energy use breakdown for type B (adapted from Dascalaki and Santamouris, 2002) lighting; 9%

cooling; 2% lighting; 6%

cooling; 8%

cooling; 23% heating; 67% lighting; 10%

heating; 89%

%

Heating

89

Lighting Cooling

heating; 86%

reasons for consumption heat losses through envelope, ineffective use of HVAC system

%

reasons for consumption

%

Heating

86 heat losses through envelope

Heating

67

9

Lighting

6

Lighting

10

2

Cooling

8

Cooling

23

Literature review

reasons for consumption heat losses through envelope, ineffective use of HVAC system

high solar gain; excessive ventilation rates

11


Type E

Figure 12.  Energy consumption of five building types according to the climatic region (adapted from Dascalaki and Santamouris, 2002)

The building envelope is highly insulated, with double-glazed and air-tight windows. Their internal partitions have a light structure, thus providing very little thermal mass. Remarkably, solar gains alone satisfy a good part of the heating requirements; however external shading is usually inadequate and increases cooling loads. These buildings have the lowest energy consumption. The overall energy consumption is subdivided as in Figure 11.

Figure 11.  Energy use breakdown for type E (adapted from Dascalaki and Santamouris, 2002)

cooling; 36% heating; 48%

lighting; 16%

%

Heating

48

Lighting

16

Cooling

36

Literature review

reasons for consumption heat losses through envelope, ineffective use of HVAC system

Retrotting scenarios

• Improvement of the building envelope:

It is the authors’ opinion that efficient energy retrofitting options encompass systems and measures that relate with sensible use of energy efficiency and the embedding of passive solar solutions. Interventions range from individual measures, targeted on one specific building component, to combinations of actions, or scenarios, in both specific and global areas. The main areas and interventions were the following:

aimed to minimise heat losses and maximise solar gains in winter, reduce cooling load by solar control in summer and enhance daylighting.

• Use of passive systems and techniques: these interventions aim to reduce heating and cooling requirements of the building by managing solar contribution. In order to improve indoor thermal comfort, interventions include the use of thermal mass and the application of passive cooling techniques.

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• Installation of energy-saving lighting systems and use of daylight: this group of interventions focus on cutting electricity consumption for lighting, by upgrading to energy-efficient systems and reducing operating hours of the lighting systems.

• Improvement of the heating, cooling and ventilation (HVAC) systems. It included measures aimed to maximise the efficiency of the building services and the implementation of heat recovery systems.

Retrotting scenarios for type A To confirm the initial assumptions of the study, retrofitting actions on this type were focused on the reduction of the energy consumed for heating and lighting. The lighting scenario was found to reduce the energy consumption for artificial lighting by 66%, while not generating alone a relevant reduction in the total energy consumption. The HVAC scenario proved to reduce greatly the energy consumption for heating. For Continental, Mid and North Coastal regions an average saving of ca. 120 kWh/m2 was obtained, corresponding to almost 42% of the baseline values. The results from the global retrofitting scenario showed great improvements in all climatic regions. The reduction in the total energy consumption were estimated to reach 181 kWh/m2 in the North

Literature review

Coastal climate, equivalent to 55% of the initial figures (Figure 13).

Retrotting scenarios for type C Following the baseline analysis, building envelope and ventilation system were identified as the core aspects for improving the performance of this type. The impact of the lighting scenario was demonstrated to be irrelevant on the total energy consumption (Figure 14). The scenario involving control and efficiency of the ventilation system was found to result in a great reduction of energy consumption for both heating and cooling. Savings were found to be nearly 38% for heating in all climatic regions and up to 85% for cooling, thanks to the Figure 13.  Retrofitting scenarios for type A (adapted from implementation of a night ventilation strategy Dascalaki & Santamouris, 2002) combined with the use of thermal mass. The heating scenario focused on the building envelope, introducing measures such as system control and the reuse of wasted energy. Reductions in the energy consumption for this scenario were found to be significant: energy consumption for heating was estimated, on average, to be cut by nearly 80% from the initial figures, in all climatic regions. As for the cooling scenario, savings of ca. 30% in all climatic regions were obtained mainly as a results of a reduction of the infiltration rate.

Figure 14.  Retrofitting scenarios for type C (adapted from Dascalaki and Santamouris, 2002)

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3. Research methodology


3.1. Case studies and structure of the analyses The literature review has indicated that the subdivision of the office building stock into different categories - or types - is successful for the purpose of identifying common issues as well as main differences. The main criteria behind the categorization used in Section 2.4, namely degree of exposure, thermal mass, skin dependence and internal structure, are strongly linked with the level and pattern of energy use. Those aspects include a variety of issues that an effective sustainable retrofit should address. The subdivision into types paves the way for evaluating the outcome of different retrofit measures and scenarios with appreciable clarity.

the choice of the two case studies, which can benefit from close proximity to the existing public transport infrastructure. The analysis will be performed in the first instance to assess the baseline scenario, including illuminance levels and daylight distribution, winter and summer thermal conditions and the overall energy consumptions. Energy simulations will be performed by means of the software IES VE, as discussed in Section 3.2.1. Current weather data as well as future projections will be used (see also Section 3.4). The typologies of the buildings chosen as case studies is linked with those discussed in Section 2.4. In particular the deep-plan, core-dependent St Andrew’s House and shallow-plan, skin dependent Argyle House fall into type A and type C respectively, as it will be shown in Section 4.1.1 on page 23 and Section 5.1.1

The methodology of the present research, therefore, will take the cue from there. Investigations on sustainable retrofitting measures will be carried out by means of two case studies: two buildings, both in Scotland Figure 15.  The two case studies: St Andrew’s House, Glasgow (Figure 15) and both dated back in the 1960s. (right) and Argyle House, Edinburgh (left) Once iconic and boldly self-proclaiming with a similar architectural language, the two buildings became nevertheless outdated both functionally and technologically. Work-related transport has been identified, together with building operation, as one of the main sources of CO2 emissions for office buildings (van de Wetering and Wyatt, 2010). Accordingly, location is a key criterion for Research methodology

on page 53. As it has been demonstrated that those two types present the highest energy consumptions of all (Figure 13 and Figure 14 on page 13), following Dascalaki and Santamouris (2002) the author foresees the highest potential for improving energy performance and indoor working conditions. Retrofitting measures will be proposed and tested through the software, with the use of iterative techniques to aid special focus on specific aspects of design and strategy.

3.1.1. The notional building In order to estimate the environmental performance of a building, the baseline criteria must first be established. In 2008 the concept of Notional Building for non-residential buildings was introduced as part of a broader regulatory scheme: the National Calculation Methodology (abbreviated as NCM). The aim was to provide the industry with a consistent regulatory basis as well as giving guidance on approved software tools for calculating carbon emissions and asset ratings (DCLG, 2008). The Notional Building (abbreviated as NB) could be defined as a simplified full-scale replica of the actual building. The NCM guide (ibid) provides an extensive definition of the NB based on each aspect that affects its thermal behaviour.

15


Site, orientation, building mass The size, shape and zoning layout for the NB must be the same as the actual building. The notional and actual buildings must have the same orientation and be exposed to the same weather. Site shading from adjacent buildings shall be reproduced for the NB.

Functions and activities Each room or area must host the same activities as its equivalent space in the actual building. Activity parameters for different classes of building are contained in a set of databases which form a key part of the NCM (ibid).

HVAC systems System types for heating, ventilation and cooling for different zones of the NB have to match what is provided for the equivalent zones in the actual building. As for the present research, the two buildings will be modelled following the definition of NB. However, in order to gather data as accurately as possible, standard values for main categories (i.e. building fabric, HVAC systems, occupancy) will be assumed only when further investigations will not be possible.

Research methodology

3.2. Interview with Stephen McHard at Wallace Whittle Considering that the object of the study deals with issues not purely academic but rather linked to professional experience, it was believed that key players of the industry could provide useful insight to inform research. Accordingly, Wallace Whittle, an international consulting firm with more than 40 years of professional experience in the field, was consulted for their advice. An informal interview with one of the director of the Glasgow office, Mr Stephen McHard, provided useful guidance in developing a coherent methodology, identifying priorities and limitations of the analyses. Moreover he gave useful insights into the practical application of environmental analyses.

the introduction of building control - energy performance as mandatory.

3.2.2. Advantages and disadvantages of using IES The reliability of IES as an interrogation and analysis tool has been widely demonstrated as an established point of reference within the industry. A large part of academic research and professional accreditations bodies have adopted it as a standard tool ever since its rapid surge. Many established consulting firms, such as Wallace Whittle, have been using it extensively to assist architectural design. Capable of informing design choices right from the early stages, the tool can produce very accurate and detailed results.

However it is the author’s opinion that its biggest advantage is also potentially its 3.2.1. Environmental modelling through biggest disadvantage. Like any tool capable computer software of providing a highly innovative consultative input through a remarkable analytical precision, Computer software has changed the way it is indeed susceptible to major errors. Minor environmental modelling and performance assessments are performed. Innovative software discrepancies in some key sensitive input packages, such as Integrated Environmental parameters, identified in Section 3.2.3, can Solutions (IES) Virtual Environment, have at determine widely divergent results. As a times contributed to definitions of regulatory consequence even through systematic analysis, infrastructure by ‘measuring’ sustainability. approximate assumptions can eventually lead to In the UK the use of software for environmental misleading conclusions. modelling has seen a rapid and constant growth For the purpose of this study, specifically for within the industry since 2010. This followed the two case studies, IES will prove to be a

16


powerful tool able to help diagnose existing issues and assess the effectiveness of proposed retrofitting measures. This should not lead the reader to think that the results will be presented as indisputable scientific evidence. They will be instead discussed, and their value reviewed in the light of the boundary conditions.

3.2.3. Sensitive parameters: infiltration When assessing the baseline conditions of an existing office building, we are to deal with some important parameters that are not at all easy to determine. This is particularly true for the case studies, since they evaluate buildings that were erected more than 40 years ago (e.g. St. Andrew’s House in Glasgow and Argyle House in Edinburgh). Air tightness, for instance, cannot be assessed without air leakage testing, which is a fairly demanding procedure in terms of both human resources and equipment. It is common procedure to assume standard values based on average buildings of the same time, unless data based on project specifications (i.e. detailed section drawings) or field investigations lead to different assumptions. The National Calculation Methodology assumed a standard parameter defining the envelope leakage; that parameter will be assumed for the energy simulations run in the two case studies.

Research methodology

3.2.4. Sensitive parameters: occupancy Occupancy is once again a very sensitive variable that can change the building requirements significantly, in terms of heating and cooling demands. The proliferation of open plan and flexible areas, which until the end of last century were mainly aimed at improving working conditions (as discussed in Section 2.1 on page 4) has in recent years drifted away from its original purpose, in the name of productivity enhance and investment maximisation. As the British Council for Offices (henceforth BCO) reports, the average density of workplaces had increased dramatically in the last decade. The average office density (the net area per person) was reported to be 11.8 sqm (British Council for Offices, 2009a), which is 40% more than the 16.6 sqm cited in the 1997 guide. Research from the BCO revealed, however, that this rise in workplace density does not necessarily imply that offices are becoming more crowded (British Council for Offices, 2009b). Instead, highly innovative design and technological advance were credited for a more efficient use of office space, allowing a higher flexibility together with improvements in comfort and amenity (ibid).

workplaces in the UK have far exceeded the density of 10 m2/person, assumed as a standard by the BCO (2009a). According to McHard, occupants density peaks of 6 m2/person are becoming more and more common as ‘efficient’ open plan workplaces multiply. In terms of energy performance, high densities of occupants and equipment add to the intensive incidental gains that derive from artificial lighting. As a result even at northern UK latitudes and fairly cold climates (i.e. Edinburgh and Glasgow) cooling loads are surpassing heating loads in commercial buildings. In other words, as McHard would put it, “heat is the enemy”.

Stephen McHard, director at Wallace Whittle, has a different opinion. Based on his professional experience, he argues that many

17


3.3. Passive measures and adaptive comfort The concept of thermal comfort has been broadly covered in academic literature to date. It is not the intention of this paper to fully cover the topic, but rather to focus on the implications on this study of the adaptive approach. As many scholars have observed (Nicol, Humphreys, and Roaf, 2012) thermal adaptation is fundamentally a dynamic process. The static connotation of comfort as a ‘finished product’ to be provided for occupants has been superseded by the idea that comfort is rather the achievement of users who are able to exert an intentional control over their environment. Building occupants may experience constraints in their operational possibilities to achieve their thermal comfort, depending on both the building fabric and its services. Furthermore the ranges of indoor climates that occupants can adapt to, are proved to vary according to physiological as well as climatic, cultural and socio-economical factors (ibid). Dynamic models were developed, offering a different approach to comfort, without assuming that only a single temperature is acceptable. Commissioned by the European Commission, the Smart Controls and Thermal Comfort (SCAT) project developed equations for comfort temperatures for different modes of operation (Nicol and McCartney, 2001),

Research methodology

freedom for the design of sustainable buildings in relation to the running mean outdoor temperature (Trm) : (Nicol and Humphreys, 2009). Free-running : Tcomf = 0,33 Trm + 18,8; Heated or cooled: Tcomf = 0,09 Trm + 22,6. where free-running refers to a building that is neither being mechanically heated nor cooled. The equations point out how indoor comfort temperatures gradually adapt to a change in the outdoor temperatures (see also Figure 16). Zones of comfort temperatures were assumed to extend by ±2K, extending the range of comfort temperatures (Nicol and Humphreys, 2007). As a consequence in a naturally ventilated office in the UK, where the running mean outdoor temperature rarely exceeds 20°C, temperatures up to 27,4 °C would still be acceptable (Figure Figure 16.  Comfort temperatures for buildings in free-running mode (continuous line) and heated or cooled mode (dashed line) 17) (Nicol, Humphreys, and Roaf, 2012). For (Nicol and Humphreys, 2007) a cooled building, the upper limit would be two degrees lower, confirming how passive strategies lead to a fairly broader tolerance in terms of perceived indoor comfort. Current standards are based on a strict notion of an ‘optimum environment’ and compliance with them often confronts the implementation of passive measures in low-carbon buildings. The adaptive approach permits the definition of indoor comfort conditions that can be accordant/compatible with low-carbon technologies in buildings. New standards are advocated in defining satisfactory conditions in buildings, with the aim of allowing greater

Figure 17.  Comfort zones for buildings in free-running mode (continuous line) and heated or cooled mode (dashed line) (Nicol and Humphreys, 2007)

18


3.4. Climate data: reference years 3.5. Simulation parameters and future projections For each analysis, a brief summary of the

The present research intends to test, through the case studies, the buildings robustness and their ability to respond to climatic scenarios that are likely to occur during their lifetime, particularly when the latter is extended through refurbishment. The environmental analyses shall employ weather data that was generated by the University of Exeter (Eames, Kershaw, and Coley, 2011) starting from the results of UKCP09.

10% pr obability level Very unlikely to be less than

50% pr obability level Central estimate

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

90% pr obability level Very unlikely to be greater than

Winter

The UK Climate Projections (UKCP09) provided a spread of possible outcomes, expressed as probabilistic projections of climate change for certain key variables (Jenkins, 2009).

parameters in use will be presented throughout the case studies in the form of a table (Table 4). A breakdown of the simulation parameters used in the study is reported in “APPENDIX A. Input parameters for energy simulations with IES” on page I.

Summer

It has been demonstrated and largely acknowledged that the impact of climate change on UK buildings, both in terms of design and energy use, will be significant. The weather data that has been used by industry-standard environmental modelling up to date, namely test reference year (TRY) and design summer year (DSY), combines data that fails to represent the current UK climate, not to mention future trends. What is more, many buildings are not being designed to adapt to climatic change and to all the alterations that go with it.

Table 4.  Template table for the parameters used in the environmental simulations

0

1

2

3 4 5 6 Change in mean temperatur

7 8 e (˚C)

9

10

Figure 18.  Changes to the average daily mean temperature by the 2080s, under the Medium emissions scenario (Jenkins, 2009).

Research methodology

19


3.6. Retrofitting scenarios Following the approach adopted in the Office project (Dascalaki and Santamouris, 2002), retrofitting actions will be organised into main scenarios. Table 5.  Retrofitting actions and scenarios. Different colours (from light yellow to orange) indicate incremental level of retrofitting.

Retrofitting scenario

Retrofitting actions

Building envelope Air leakage Insulation levels Winter solar gains Summer solar gains

Weather stripping of windows/doors or replacement of window frames in bad condition. Replacement of external windows Ameliorate insulation levels for external walls and replacement of existing windows with double glazing. Façade recladding. Optimise openings orientation and redesign office layout to maximise solar gain without interfering with office functions. Reduce window area Internal or mid-pane blinds Solar control glazing External shading devices

Heating cooling and ventilation systems HVAC system efficiency HVAC system management Lighting systems and use of daylight Lighting system efficiency Improvement of daylight

Utilisation of heat recovery systems. Maximise HVAC efficiency, through replacement of boilers. Install a Building Management System (BMS) Decrease of the general lighting and use task lighting. Automatic control of artificial lighting via presence sensors and time-scheduled control. Automatic control of artificial lighting via daylight sensors. Increase the amount of external glazing. Introduce light shelves

Passive systems and techniques Passive solar Thermal mass Ventilation

Research methodology

External shading devices to maximise solar gain in winter and minimise it in summer. Remove false ceilings and/or carpets to expose thermal mass. Implement forms of natural ventilation, adapting the internal office layout. Night ventilation. Introduce atrium Introduce a double façade

20


4. Case study: St Andrew’s House, Glasgow


4.1. St Andrew’s House, Glasgow St Andrew House is a mixed use mid-rise skyscraper located in the heart of Glasgow city centre, at the crossing between Sauchiehall and West Nile Street. Designed in 1961 by Arthur Swift and Partners and completed in 1964, it was at the time one of the first high-rise buildings in the city centre; its location as well as its massing made it a prominent landmark ever since. The building consists of two distinct parts: the three-storey podium and the 14-storey tower. Horizontal and vertical emphasis are juxtaposed Figure 19.  Bird-eye view (adapted from Microsoft, 2012b) with remarkable clarity of mass and form. Figure 20.  Street view of St Andrew House (Urquhart, 2010)

Case study: St Andrew’s House, Glasgow

Figure 21.  Location plan (adapted from Glasgow City Council, 2009).

22


4.1.1. Building typology The deep plan structure reminds those of type 3 buildings (BRE, 2000) as classified in Section 2.1 (see Figure 22). As anticipated, the building falls into type A (Table 6) defined by the Office project. It features a high ratio between volume and envelope surface, concrete floor and ceilings and large perimeter glazed areas. Ventilation rates together with elevated heat losses through the fabric are expected to add on the heating requirements. Moreover the deep plan precludes a satisfactory daylight penetration, increasing the reliance on artificial lighting. As a result St Andrew’s House, like all the buildings of type A is expected to have a very high energy consumption. Figure 22.  Typical plan zoning for a deep plan office building (BRE, 2000)

Case study: St Andrew’s House, Glasgow

The typical tower floor plan, from 3rd to 17th floor, has three zones: a central services core, an outer corridor and offices all around (Figure 22). The office space is mostly cellular, although some floors have open plan areas.

Table 6.  Characteristics for type A buildings (adapted from Dascalaki and Santamouris, 2002).

degree of exposure Free standing Type A

X

enclosed

thermal mass heavy X

Figure 23.  St Andrew’s House - typical floor plan (Swift and Partners, 1961). Internal partitions are here not represented.

light

skin dependence

internal structure

Skin dep.

Core dep.

Open plan

X

X

cellular

Figure 24.  St Andrew’s House - typical floor plan (Glasgow City Council, 2009)

23


4.1.2. Existing issues

Figure 26.  Cross section on lavatories (Swift and Partners, 1961)

While the podium still retained its commercial tenants, the office tower fails to meet the standard requirements in terms of quality, flexibility and size of a modern office space and remains largely vacant. Some major issues derive from the buildings restrictive internal layout. Such is the location of toilets at a mezzanine level, accessible only through the main stairs (Figure 26), that is highly nonfunctional and makes it hard to comply with current regulations of disabled access.

Figure 27.  Existing cladding (Glasgow City Council, 2007)

Figure 25.  Cross section on stairs (Swift and Partners, 1961)

The building fabric is also in a poor condition (Figure 27): the external prefabricated concrete cladding is “failing” (Glasgow City Council, 2007) presenting a critical health and safety issue. Safety cradles had to be erected above Sauchiehall Street and West Nile Street to avoid falling masonry (see Figure 28). Figure 28.  Safety cranes (highlighted) were installed to arrest falling masonry (adapted from Glasgow City Council, 2007)

Case study: St Andrew’s House, Glasgow

24


4.2. Office and hotel: occupancy and function in retrofitting

on some passive measures (e.g. cooling through night-time ventilation).

Saint Andrew House has undergone, from 2009, a redevelopment aimed to bring back into use a high profile tower block in the City Centre, to provide retail space and a 210 bedroom hotel. The scheme has benefitted from the previously mentioned Business Premises Renovation Allowance (BPRA), which provided a complete tax relief on capital expenditure incurred on the conversion of this almost unused premise.

As it can be observed from comparing Figure 30 to Figure 31, the redevelopment did not bring major alterations to the existing floor plan. The central core is maintained to distribute people and services and the rooms are distributed around the perimeter, served by one ring corridor.

Other than market or financial considerations, it Figure 29.  Architectural rendering of refurbishment project seems interesting for the purpose of this study (Glasgow City Council, 2009) to analyse the consequences in terms of comfort and energy performance deriving from different functions. The type of occupancy induces different requirements in terms of daylight levels and thermal comfort. As for daylight, hotel rooms’ requirements are not at all stringent; rooms can be occupied throughout the whole day, although guests will mostly be there at night. External windows are intended to provide view to the outside and to barely satisfy a legal requirement, rather than an asset strategy for visual comfort.

Figure 30.  Existing floor plan for typical floor (Glasgow City Council, 2009)

Key core

corridors

Figure 31.  Proposed floor plan for typical floor (Glasgow City Council, 2009)

Regarding thermal comfort, hotel rooms demand prompt response from the HVAC system, usually giving occupants a fair level of control over the room temperature. At the same time the ‘cellular’ layout together with the occupancy schedule preclude the chance to rely Case study: St Andrew’s House, Glasgow

25


4.3. Analysis model Different layouts lead to fairly different thermal performances and daylight distributions. As it can be observed from Figure 33 the existing plan structure is rather messy and inconsistent from floor to floor, probably deriving from the presence of different tenants at each floor with different occupancy and use patterns. However, for the purpose of thermal and daylight analyses, some degree of simplification Figure 33.  Existing floor plans (Glasgow City Council, 2009) shall be adopted. The modelled scenario comprises, for the typical floor plan, six main Key enclosed office rooms, distributed along a cellular offices * stairs and elevators ring corridor around the core. The detailed corridor toilets analyses will focus on the rooms facing south, particularly on the room facing south-east (highlighted in Figure 32).

Figure 32.  SketchUp model of cellular layout

* *

Case study: St Andrew’s House, Glasgow

*

26


4.4. Winter thermal performance and annual energy consumption

Table 8.  Annual energy consumption for St Andrew’s House baseline scenario

The purpose of testing the winter performance of the building is to assess energy consumptions due to heating and artificial lighting. The whole year, and not just the month of January, is thus considered: parameters are listed in Table 7.

Baseline annual electrical consumption:

The tests show a quite elevated heating plan sensible load, caused to heat losses that derive both from the poor insulation properties of the existing fabric and the high contribution of infiltration (NCM 10 m3/(h·m2) at 50 Pa is assumed). If the results, here presented in Table 8, are compared with those reported on Section 2.4, it can be observed that energy consumptions for St Andrew’s House are comparable with those of Type A buildings for Mid and North Coastal climates (Figure 35). This result has to be intended not as an accurate estimate of the building’s consumption but rather a confirmation of the hypotheses initially made (Section 4.1.1).

239.1 kWh/m2.yr

77.6 kWh/m2.yr 71.7 kgCO2/m2.yr

Figure 34.  Annual energy consumption for St Andrew’s House baseline scenario

electrical; 25%

Baseline annual thermal consumption: thermal; 75%

43.1 kg CO2/m2.yr

Table 7.  Simulation parameters for baseline situation (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Case study: St Andrew’s House, Glasgow

B1.01 try w xuv fc chr ncm min dod

St Andrew’s House Figure 35.  Energy consumption for Argyle House in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)

27


4.5. Summer thermal performance CIBSE set benchmark summer peak temperatures for non air-conditioned office buildings as 28°C (CIBSE, 2006). The overheating criterion corresponds to 1% of the annual occupied hours over 28°C, assuming warm summer conditions in UK. The simulation aims to assess if the building ‘overheats’ according to this criterion, with a default occupancy pattern of 8am-6pm, Monday to Friday (Table 9). The temperatures for all the office rooms (corridor, toilets, stairs and elevators have not been considered in the analysis) point out some reasons for concern (Figure 36). Although it appears that the building is not strictly overheating according to the CIBSE criterion, air temperature exceeds 25°C for several hours during the month of July (Table 10). Table 9.  Simulation parameters for baseline situation (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Case study: St Andrew’s House, Glasgow

B1.02 try s xuv fc nv ncm min dod

outdoor air temperature

Figure 36.  Summer air temperatures for all the office rooms (different colours). Dry-bulb outdoor air temperature in light green.

Table 10.  Summer indoor air temperatures over 25°C and 28°C during occupied hours.

Figure 37.  Sources of heat during summer (Rennie and Parand, 1998)

temperature Air temperature Location Air > 25°C (hours) > 28°C (hours) 01_010 01_011 01_002 01_003 01_006 01_005 Total hours

4.0 4.0 0.0 3.0 7.0 4.0

0 0 0 0 0 0

22.0

0

28


4.5.1. Natural ventilation in exposed tall as the high percentage of dissatisfied people, buildings reaching over 50%, points out (Figure 38).

Figure 39.  Volume flows of incoming air (blue) for a room facing south-east on a windy day.

Relying on passive measures such as natural ventilation is not always feasible, particularly for inner city development, where noise and pollution are key issues. The variability of wind pressure in direction and distribution makes it difficult to achieve a consistent level of performance for naturally ventilated buildings. Tall exposed buildings represents in that sense a bigger challenge since wind velocities, which increase with height above the ground, can cause excessive flow rates in summer. Those are unacceptable particularly in office buildings, where the indoor air speed is generally strictly controlled (e.g. to avoid papers being blown off desks) (Dye and McEvoy, 2008). Figure 38.  On a windy day (30th July) the conspicuous volume of external ventilation (blue) is the main reason for the divergence

Tests on IES appear to confirm that the problem between air temperature (green) and dry resultant temperature (grey). That results in a high PPD value (red). exists for St Andrew’s House, a tall tower exposed on three main elevations. Although the control parameters are quite simplistic if compared the actual scenario and wind distributions are based on statistics on a macro scale, results highlight an aspect that deserve consideration. On a summer day (i.e. 30th July) when wind speeds range between 10 to14 m/s, a naturally-ventilated room facing south-east receives peaks of air flow of more than 10000 l/s (Figure 39). Being the floor area 243 m2, that would corresponds to a value of ca. 148 ach. That leads to uncomfortable indoor conditions,

Case study: St Andrew’s House, Glasgow

29


4.6. Daylight Illuminance ranges, adopted from the Illuminating Engineering Society (IES), define the amount of light required for different activities (Kaufman, Christensen and IES, 1987). Most of office activities fall into Illuminance Category D, thus requiring a medium illuminance level of 300 lux (Table 11). The required daylight figures needed to provide the minimum level of illumination of 200 lux corresponds to 4.5 (Table 12). The daylight analysis for the case study is performed with a CIE standard overcast sky, on 21st September (autumn equinox) at 12 am. Results show an acceptable average daylight factor (Figure 40) although daylight distribution is not really satisfactory. As a matter of fact area that sits below the medium illuminance level (300 lux) is too large (as Figure 41 shows).

room 03

room 02

room 06

room 05

room 11

room 10

Figure 40.  Daylight factor for typical floor

Table 11.  Illuminance Categories and Lux Ranges (Kaufman, Christensen and IES, 1987)

Illuminance Category

Lux Range Table 12.  Required minimum daylight factors, grouped by latitude (DeKay, 2010).

Low

Medium

High

A

20

30

50

B

50

75

100

Latitude

Required DF

C

100

150

200

28°-38°

1.5-2.0

D

200

300

500

40°-48°

2.5-3.0

E

500

750

1000

50°-52°

3.5-4.0

F

1000

1500

2000

54°

4.5

Case study: St Andrew’s House, Glasgow

Figure 41.  Areas below 300 lux for typical (green)

30


4.6.1. Daylight uniformity

Figure 43.  Uniformity ratios

As a general rule of thumb the penetration of daylight from openings on perimeter walls is generally considered to be limited to about 2.5 times the height of the opening above the floor. This general rule however does not account for light distribution uniformity, that determines the depth limit for a sidelit room. The room’s size, its proportions and the reflectance of its surfaces all affect the allowable depth for daylight (Figure 42). At the same instance illuminance ratios have to be contained within the optimum Figure 42.  Estimating maximum room depth for daylight uniformity (Brown and DeKay, 2000) range in order to minimise the perception of glare. Table 13.  Daylight calculation results for typical floor

Uniformity ratio The ratio between the minimum illuminance and the average illuminance on a plane, or the uniformity ratio, indicates the degree of “evenness” of natural light. When the depth of the room does not exceed the ceiling height, light is fairly uniform and UR stands around 0.2. UR between 0.1 and 0.2 are still acceptable; as the room gets deeper UR falls under 0.1, resulting in visual discomfort (Figure 43). It appears from that UR value for the typical floor plan is not excellent, being around the threshold value of 0.1; an improvement is very much desirable.

Case study: St Andrew’s House, Glasgow

Uniformity min / avg

Diversity min / max

6.4 % 22.5 % 781.5 lux 2744 lux

0.12

0.03

0.6 % 70.4 lux

6.3 % 764.2 lux

21.9 % 2674lux

0.09

0.03

Daylight Factor DL illuminance

0.4 % 50.5 lux

4.3 % 20.7 % 521.7 lux 2534 lux

0.10

0.02

room 05

Daylight Factor DL illuminance

0.6 % 75.5 lux

4.2 % 512.7 lux

19.7 % 2411lux

0.15

0.03

room 10

Daylight Factor DL illuminance

0.9 % 6.5 % 21.9 % 110.5 lux 790.6 lux 2670 lux

0.14

0.04

room 11

Daylight Factor DL illuminance

0.7 % 80.1 lux

0.10

0.03

Location

Quantity

room 02

Daylight Factor DL illuminance

0.8 % 93.9 lux

room 03

Daylight Factor DL illuminance

room 06

min

values avg

max

6.4 % 22.4% 782.7 lux 2738 lux

31


4.7. Retrofitting scenarios: building envelope

Figure 44.  Existing PC panels (Glasgow City Council, 2009)

Figure 45.  Section on external cladding (Swift and Partners, 1961)

4.7.1. Air leakage and insulation levels The choice of weather stripping external windows is here not considered. As previously discussed the fabric, in its present state, does not meet the performance requirements for a modern offices. Cladding has reached the end of its life and urgently needs replacement. The use of double-walls, which could and should be evaluated when the building’s façades are in good conditions or present considerable architectural value (i.e. for listed buildings) is on this occasion considered redundant and ineffective.

Figure 47.  Removal operations in St Andrew’s House (Urquhart, 2011)

4.7.2. Façade recladding 4.7.2.1. Existing external wall system Information about the existing fabric was obtained by means of a bibliographic research at Mitchell Library archives (Swift and Partners, 1961).

Figure 46.  Creating a database for the existing fabric in IES Apache database (see APPENDIX A for details)

The detailed section reads “4” spandrel usp (perhaps standing for Unitised Spandrel Panel) and precast sill and cladding unit” (Figure 45). Accordingly, the construction is modelled in IES, resulting in a U-value of ca. 1.6 W/(m2·K) (Figure 46).

Case study: St Andrew’s House, Glasgow

32


4.7.2.2. New external wall system Recladding can dramatically improve the U-value and, most importantly, the airtightness of the building fabric. Many systems exist on the market: a typical dry-wall system (Figure 48) appears suitable for the purpose. Figure 49 presents a few types of dry-wall constructions that are industry standards: 1. Exterior wall construction between floors. 2. Exterior wall construction between floors with additional exterior thermal insulation.

The different type of constructions offer higher U-values and reductions of thermal bridges, higher thermal mass and overall better performances (e.g. ventilated constructions for south-facing walls). At the same time they present additional construction costs. A new simulation is then performed to evaluate the impact of the building envelope scenario, accounting for both the updated U-values and the improved airtightness. The parameters in use, both for the baseline and the new situation, are listed in Table 14.

3. Exterior wall construction in front of floors.

Figure 48.  Dry-wall construction basic scheme (Knauf, 2012)

Figure 49.  Types of new wall constructions (adapted from Knauf, 2012) Key

external cladding

internal finish

insulation

existing structure

4. Ventilated construction, exterior wall between floors behind cladding. 1 U-value 0.80-0.28 W/m²K

2 U-value 0.33-0.35 W/m²K

Table 14.  Simulation parameters for building envelope scenario (see APPENDIX A for details)

Figure 50.  Adding the new construction in IES Apache database for new energy simulation

Case study: St Andrew’s House, Glasgow

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

B1.03 try w nuv fc chr ncm min dod

3 U-value 0.20-0.18 W/m²K

4 U-value 0.26-0.28 W/m²K

Note: U-values refer only to systems illustrated in (Knauf, 2012)

33


It appears that the replacement of existing external walls with a high performance dry wall construction, with considerable update in terms of U-value (from 1.58 to 0.28 W/m²K) does not result alone in a considerable difference in terms of heat losses through the fabric. It could be expected that the very poor thermal performance of the existing single-glazed windows would affect the outer envelope’s performance the most. This is indeed true, as Figure 51 shows: the improvement in opaque partitions, although appreciable, does not bring alone a satisfactory improvement to the building’s performance. Major heat losses happen through the glazing: the replacement of the existing glazing (estimated U-value= 5.23 W/m²K) with the industry standard lowemissive double glazing (U-value=1.98 W/ m²K) produces more remarkable effects (Figure 52).

Assuming a default HVAC system (see Section 4.8 on page 39 for further information) the savings in terms of energy consumptions are as follows:

walls

glazing

Annual thermal consumptions XUV

NUV

239.4 kWh/m2.yr

187.1 kWh/m2.yr

43.1 kg CO2/m2.yr

33.7 kg CO2/m2.yr

Which represents a 22% reduction in both energy consumptions and carbon emissions.

Figure 51.  Daily heat gains and losses for existing (orange) and replaced (brown) external walls, in comparison to glazing (blue) replaced existing

Figure 53.  Heat gains and losses over a week-time in winter

Figure 52.  Daily heat gains and losses for existing (blue) and replaced glazing (cyan)

It is important to remark that any recladding action on the building shall certainly imply a total replacement of the components of the existing skin: the process described above is deliberately ‘fictitious’ and set out to isolate which parts of the fabric affect the building’s performance the most. Ultimately it can be noted how, on a weekly basis, the overall external conduction gain benefits are relevant both at day and at night (Figure 53).

Case study: St Andrew’s House, Glasgow

34


4.7.2.3. Air tight envelope A new test is run with an updated value of air-tightness. It is assumed that the recladding will achieve innovative standards in terms of airtightness: the value of 2 m3/hm2 at 50 Pa (as specified in Section 3.5 “Simulation parameters” on page 19). The new parameters are listed in Table 15. A comparison is drawn between the sensible heating loads for the three scenarios:

Table 15.  Simulation parameters for building envelope scenario, with improved airtightness (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

B1.04 try w nuv fc chr iat min dod

• XUV: existing external fabric; • NUV: new fabric after recladding, with unmodified infiltration; • NUV+IAT: new fabric with improved values of air tightness. The divergence is important, as Figure 55 points out.

Figure 55.  Enlarged view of Figure 54, showing the heating loads for the first week of January

Figure 54.  Heating loads in comparison for the whole month of January: XUV (red), NUV (orange) and NUV tight (yellow).

Case study: St Andrew’s House, Glasgow

35


As for energy consumptions, the following results are obtained assuming a HVAC system with default efficiency, as specified in Section 3.5 on page 19. The results are presented in tabular (Table 16) and graphic (Figure 56) versions. Although, as previously discussed, the numeric values obtained in terms of energy consumption and CO2 emissions depend on a number of critical assumptions, what is notable is the relative reduction of those, expressed here by means of percentages. The results confirm the relevant impact of building envelope scenario for the present case study.

Table 16.  Thermal energy consumptions and emissions for three retrofitting scenarios

Annual thermal consumption Existing fabric (XUV)

New fabric (NUV)

New envelope and innovative air-tightness (NUV+IAT)

239.4 kWh/m2.yr 43.1 kg CO2/m2.yr

187.1 kWh/m2.yr 33.7 kg CO2/m2.yr

95.8 kWh/m2.yr 17.3 kg CO2/m2.yr

21,8% reduction

60% reduction

Key

thermal emissions

thermal energy

XUV NUV NUV + IAT Figure 56.  Thermal energy consumptions and emissions for three retrofitting scenarios

Case study: St Andrew’s House, Glasgow

36


4.7.3. Summer solar gains 4.7.3.1. Reduce window area Reducing window area can be seen as a simplistic, low-technology solution. Furthemore Figure 57.  South elevation enlarged to assess the glazing ratio it can make the arrangement of the internal (adapted from Glasgow City Council, 2009) layout more problematic, particularly for cellular office layouts, where individual rooms have more limited access to daylight. For the building under analysis, for instance, some narrow and long rooms would hardly meet daylight requirements with a reduction in the openings in number or size. In this aspect open plan office layouts offer a greater flexibility, allowing to reduce external glazing without drastically compromising the visual comfort. All the façades of St Andrew’s House currently have the same amount of glazed surfaces on each floor, corrsponding to 30,24 m2 . The glazing ratio is approximately 40,4% (Figure 57). The reduction of glazed area, if operated, should be selective and articulate according to the different orientations.

Case study: St Andrew’s House, Glasgow

6310

Figure 58.  South elevation on Sauchiehall Street (Glasgow City Council, 2009) 5970

5630

5290

4950

4610

4270

3930

3590

3250

2910

37


4.7.3.2. Internal or mid-pane blinds Internal blinds have a minimum installation cost and for that reason have been adopted largely as tool for solar control in office buildings throughout the world. However they offer very low resistance to solar gain, allowing some 50% of solar gain inside the room (Rennie and Parand, 1998). Mid-pane blinds are certainly more effective, transmitting on average only 30% of solar gain. Their use would permit a reduction of temperature by ca.1-2°C in comparison to internal venetian blinds. They present increased initial costs, needed to replace the existing glazing, but require low maintenance and offer performances that are constantly increasing thanks to a receptive market.

4.7.3.3. Solar control glazing

Figure 59.  Shading types: internal blinds (top left and bottom left), mid-pane blinds (top right), external louvres (bottom right) (adapted from Rennie and Parand, 1998)

ht

lig

sun

ligh

t

se

ffu

di

y da

slats adjusted to just exclude the sun's rays some view out

30% double glazing

50% double glazing

10% double glazing

Figure 60.  Interior view of the offices in St Andrew’s House: internal blinds are installed (Glasgow City Council, 2007)

Variable transmission glazing may represent an advantage if heat gains and heat losses are required in different periods of the year. Most of the developments in glazing types have been directed at reducing the solar radiant heat transmission characteristics of clear glass. Low heat transmission glazing are of two kinds: heat absorbing, and heat reflecting. Solar control glass reduces the transmission of both light and heat, although types in the heat-absorbing category will warm up and reradiate some heat into the room. But very few types of glass

Case study: St Andrew’s House, Glasgow

38


reduce heat more than light. And even glass with the lowest light transmission is unlikely to reduce glare from the sun significantly; this is because the sun is exceedingly bright compared with the relatively low luminance of surfaces in the room.

4.7.3.4. External shading devices Of all shading devices external devices are the most effective at controlling solar heat gains. A white louvered sun breaker, with blades at 45° for instance would admit only 10% of solar gain (Figure 59). Size and shape of the louvres vary according to the latitude and orientation of the building. As a general rule of thumb south-facing façades are best protected with horizontal elements whilst east and west façades benefit from the use of vertical elements. In a continental climate the design of external shading devices should aim to maximise solar exposure during winter, while glare issues, and minimise it during summer. Detailed analyses will be carried out in the following chapter, as part of the passive solar retrofitting scenario.

4.8. Retrofitting scenarios: HVAC system A software default central heating system with radiators (seasonal efficiency of 0,89) was assumed for the building. Further research was not possible, even if some photographic documentation suggest the presence of fancoils instead (see Figure 60 on the previous page). The HVAC retrofitting scenario will not be investigated for this case study. Energy consumption assessments are focused mainly on building fabric, including aspects such as insulation, thermal mass and infiltration. The analyses, as seen before, shall use HVAC system assumptions as a reference for comparing results, focusing on relative rather than absolute values. Figure 61.  External shading types (adapted from CIBSE, 2004)

overhangs

reveals

Case study: St Andrew’s House, Glasgow

horizontal overhang

vertical sun-screen

rotating panel

rollershades

awning

shutters sliding or rotating

horizontal and vertical overhangs

vertical movable louvres

39


4.9. Retrofitting scenarios: lighting systems and use of daylight 4.9.1. Lighting system efficiency The reduction of general lighting level brings immediate benefits in terms of energy savings. For most office activities falling into Illuminance Category D (see Table 11 on page 30) the maximum illuminance level of 500 lux can be cut down to a medium value of 300 lux, still satisfactory, provided that the lighting system is implemented with localised task lighing. The rearrangement of the internal layout to group together areas with same illuminance requirements can accomodate a selective reduction of illuminance levels that would not be detrimental for visual comfort. Sensors and time-scheduled control of lighting offer electrical energy savings, albeit requiring an initial expenditure to install a Building Management System.

4.9.2. Improvement of daylight Considering that the case study is a building with an already elevated glazing ratio, there is not much room for increase. Additionally, modifying the glazing ratio of any façade will have an impact on solar summer gains, as discussed in the previous chapter. The challenge is to find a balance between the two. Case study: St Andrew’s House, Glasgow

4.9.2.1. Light shelves It has been documented that, although light shelves actually do not increase daylight penetration in a room considerably, they can improve the uniformity of lighting by reducing the elevated DL levels at the front of the room (Rennie and Parand, 1998). They are placed above eye-level and divide the window into two parts, usually acting as shading devices as well. For that purpose they are generally more effective when they are both internal and external (ibid).

Figure 62.  Impact of a light shelf on illumination levels (adapted from Rennie and Parand, 1998). average illumination illumination with light shelves The introduction of light shelves abates the maximum DL levels at the front without reducing the minimum values at the back (red curve). As a result DL distribution within the room is more uniform.

Figure 63.  Effects of external and internal light shelves (above) and distribution of light with different angles (below) (ibid)

Figure 64 shows a rule of thumb for sizing a light shelf for a south-facing room, with the internal part being smaller than the external one. Light shelves can be implemented into St Andrew’s House, that satisfies the minimum requirement of 3 meters internal floor-toceilings height (provided that false ceilings are removed).

Figure 64.  Suggested dimensions for light shelf in UK (ibid) y w=h

at least 3m

w=y h

40


4.9.3. Improvement of daylight: introducing an atrium / lightwell Atria can be designed to provide daylight as well as to facilitate ventilation. In many city centres atria and light courts have been successfully used in high-rise buildings to help the penetration of light deep into them, thus permitting high development densities with good levels of natural light. However, atria generally impose functional constraints on building form and bulk (DeKay, 2010). For a given building height, two major elements of atrium buildings determine their form: 1) the size and proportion of the atrium; 2) the thickness of the building’s wings. When used as a lighting device for adjacent spaces, the design of an atrium has to follow some rules be truly effective. The size and the proportion of an atrium can be roughly established in the early phases of design, by following the atrium sizing rule-of-thumb (Figure 65), a method that has been extensively investigated by researchers (DeKay, 2010).

4.9.3.1. Introducing an atrium in a deep plan office building When retrofitting an office building, there is a whole set of boundary conditions that need to be carefully considered. The existing structure is preserved in such a way that new infills

Case study: St Andrew’s House, Glasgow

should fit into the structural grid. Services cores often have a certain degree of structural autonomy: they are rigid boxes enclosed in reinforced concrete walls and are partly void and partly occupied by stairs, which often have an independent structure. Deep plan high-rise buildings are often articulated around a barycentric core (see Figure 22 on page 23); if the services core can be moved out and allocated elsewhere, that space can accommodate an atrium.

DF required IES C

IES D

H/L*

20-50 fc

Ratio

1.0-1.5 1.5-4.0 1.0-1.5 1.5-4.0 1.0-1.5 1.5-4.5 1.0-2.0 2.0-4.5 1.0-2.0 2.0-5.0 1.0-2.0 2.0-5.5 1.0-2.5 2.5-5.5 1.0-2.5 2.5-6.0 1.5-2.5 2.5-7.0 1.5-3.0 3.0-7.5 1.5-3.0 3.0-8.0 2.0-3.5 3.5-9.0 2.0-4.0 4.0-10.0 2.0-4.5 4.5-11.5 3.0-5.5 5.5-14.5 4.0-8.0 8.0-20.0 5.5-11.5 11.5-28.5

1.60

°Lat 10-20 fc 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60

Atria Length (L)** 4 6 story story

10 story

1.60

30 ft. 45 ft.

75 ft.

1.35 1.20

36 ft. 53 ft. 89 ft. 40 ft. 60 ft. 100 ft.

1.10 0.95 0.85 0.75 0.65 0.40 N/A

44 ft. 51 ft. 56 ft. 64 ft.

65 ft. 76 ft. 85 ft. 96 ft.

109 ft. 126 ft. 141 ft. 160 ft.

Table 17.  DF and atria proportions required under overcast sky, listed by latitude (DeKay, 2010). Notes. H = height of atrium; L=lenght of atrium. Floor-to-floor height assumed as 12ft per story. IES C-D = Illumination Engineering Society illuminance categories, used for general recommendations about light provision for a given task. As already mentioned Category D requires 20-50 fc = 200-500 lux.

Figure 65.  Sizing atria for daylight in adjacent rooms (Brown and DeKay, 2000).

41


4.9.3.2. Change of layout and reduction of rentable area

Key toilets

elevators

stairs

With regards to the observations made in the previous chapter, St Andrew’s House is a good case study for the introduction of an atrium. Following required sizes and proportions listed in Table 17, it is clear that there are no chances that the infilled atrium would provide the required DF to the entire floor plan. The current retrofit action aims to improve the DL penetration deep into the floor plan and combine it with a rearrangement of the internal layout (followingly discussed) that will allow office activities to rely on daylight as much as possible.

Figure 69.  Central atrium - perspective of the analysis model

The plan of existing floor (Figure 66) is reported together with the proposed one (Figure 67). The services are moved outside from the central core and pushed against the northern façade. Locating services on the north side shall allow to free up the access to daylight on south-east, south and south-west elevations. The existing floor plans have an average area of 450 m2 loss of 45m2, which corresponds to circa 10%. That means that, in terms of floor space and not including construction or demolition costs, if the improvement of daylight would trigger a revaluation of 10% for each sqm Figure 66.  Existing floor plan - central services core and cellular of rentable area (if compared to a standard offices along a ring corridor. refurbishment) the introduction of the central Figure 67.  Proposed floor plan - central atrium with open plan atrium could be paid off. office space and services pushed against the north façade.

Case study: St Andrew’s House, Glasgow

Figure 68.  Central atrium - perspective section

42


4.9.3.3. Designing the atrium for daylight Since the distribution of daylight in an atrium drops considerably when moving down from the top floors (as Figure 65 shows). Alongside an atrium model featuring a constant glazing ratio at every floor (Figure 70), a second one is produced, to test the progressive reduction of windows in size and number while going up in height. The 15 storeys are divided into three groups of five, each with a different glazing ratio as indicated on Figure 71. The most notable benefit, however, is a direct consequence of the glazing ratio. The reflectance of atrium surfaces has a huge effect on the distribution daylight. Windows are designed to intake the light they received and thus are generally poor reflector. Reducing glazed surfaces will make space for larger opaque surfaces, which, if properly treated, can increment the reflectance of the upper atrium.

Case study: St Andrew’s House, Glasgow

30% surfaces all white 21%

17%

28%

17%

white walls

black walls

16%

4

black floor

white floor

7%

3

Figure 72.  Different case highlight how reflections from the atrium surfaces affect daylight distribution (Rennie and Parand, 1998).

Figure 70.  Wireframe cross section of the atrium. The glazing ratio has constant value of 50% throughout the total height.

Figure 71.  Wireframe cross section. The glazing ratio is progressively reduced bottom-up.

ROOF

ROOF

L17

L17

L16

L16

L15

L15

L14

L14

L13

L13

L12

L12

L11

L11

L10

L10

L9

L9

L8

L8

L7

L7

L6

L6

L5

L5

L4

L4

L3

L3

g.ratio 16,6%

g.ratio

25%

g.ratio

50%

43


4.9.3.4. Illuminance calculations

The baseline parameters listed in Table 18 refer to the software default surface properties, e.g. brick masonry walls and average clear float glass for windows and roof light.

As mentioned above, the surface properties for both the opaque and transparent partitions can be ‘tuned’ in order to maximise the effectiveness of the atrium as a light collector Results, shown in Figure 73 below, indicate and distributor. IES Radiance is used to perform that the illuminance levels would hardly be accurate calculations of the illuminance levels satisfactory below level 17. on the rooms overlooking the atrium. Figure 73.  Atrium daylight illuminance for default surface properties Level 17

Case study: St Andrew’s House, Glasgow

Level 13

Level 8

Table 18.  Default surface properties for atrium daylight analysis

Surface properties: walls glazing ground floor internal floor / ceiling roof roof light

inside reflect. 50 7 20

outside transm. reflect. 10 7 70 -

70

20

-

70 7

10 7

70

Level 3

44


Surface properties can be improved for the purpose of enhancing daylight distribution, e.g. by using plain white render on external walls and internal ceilings and bright tiles on internal floors (see Table 19).

Table 19.  Updated surface properties for atrium daylight analysis

Surface properties: walls glazing ground floor internal floor / ceiling roof rooflight

Results shown in Figure 74 below indicate a considerable improvement, such that DL levels are acceptable until level 13. Figure 74.  Atrium daylight illuminance for default surface properties Level 17

Case study: St Andrew’s House, Glasgow

Level 13

Level 8

inside reflect. 90 5 90

outside transm. reflect. 90 5 95 -

90

90

-

90 5

90 5

95

Level 3

45


4.10. Retrofitting scenarios: passive systems and techniques 4.10.1. Passive solar 4.10.1.1. External shading devices For the typical window on the south façade three types of shading systems are considered:

Figure 75.  Insolation analysis, 21st December

Figure 78.  Insolation analysis, 21st June

Figure 76.  Shading on south façade, 21st December

Figure 77.  Shading on south façade, 21st June

1. Fixed horizontal louvre + vertical louvre on window’s right side 2. Fixed horizontal louvre + vertical louvre on window’s left side

9:15

9:00

11:15

11:00

13:30

13:00

15:15

15:00

3. Double fixed horizontal louvre. Shading is assessed at different hours of the day in winter (21st December) and summer (21st June) scenarios. On a winter day the first and second systems both limit heat gains when the sun is low in the sky, allowing solar gains during the middle of the day, while the third system offers minimum resistance to direct solar radiation. During summer, the shading systems’ effectiveness diverges more substantially. The first and second systems in facts still provide shade with the lower sun altitudes, but with considerable difference: while the first system is quite effective during the morning, the second shades the openings mostly during afternoon hours, when the outside air temperature is higher and the so is the need for cooling.

Case study: St Andrew’s House, Glasgow

3

2

1 17:00

3

2

1 46


The same calculations are carried on east and west façade, to find out the most effective configuration of external shading systems. The subdivision of the floor plate into six large office spaces (see Figure 82 on page 48) is such that rooms have orientations from east to west are covered. That subdivision allows identifying quite clearly how orientation favours solar gain throughout the day.

Room 5

With the shading systems in place, it is possible to estimate, through IES VE Apache thermal simulation, the amount of reduced solar gain for the inner rooms. Highlighting the area subtended by the curves representing the solar gains before and after the introduction of the shading devices is a good way of visualising the effectiveness of the shading devices themselves (Figure 80). As it can be noted, the highest gains, which sum up to almost 5KW are reduced by approximately 50% during the mid-hours of the day. That should indicate that such shading geometry is particularly effective with sun high altitudes.

Room 10

Room 11

LEFT Figure 79.  Solar gain (yellow) and air temperature (green) for different rooms on summer day (28th July) RIGHT Figure 80.  Solar gain comparison between baseline conditions (orange) and with new external shading devices (yellow) for different rooms on summer day (28th July)

Case study: St Andrew’s House, Glasgow

Room 6

47


4.10.1.2. Light shelves and shading devices

Figure 83.  Close-up view of shading devices for typical floor

As it has been discussed before light shelves could act as shading devices as well. They should be carefully proportioned, to serve both purposes effectively without overlapping. Focusing on the south façade the external shading devices that have been designed in the previous chapter have to be reconsidered with regards to light shelves functionality.

Figure 81.  Suggested dimensions for light shelf in UK (Rennie and Parand, 1998)

y w=h

at least 3m

w=y h

In that regard louvres can be once again looked at in three categories: - Lower horizontal louvres work as light shelves as well and thus shall receive a fair amount of daylight; - Vertical louvres partially shade the latter reducing their effectiveness. However their shading contribution, particularly during late summer afternoons, is considered to be more relevant for the building’s comfort that the amount of daylight they subtract. - Upper horizontal louvres shade the lower louvres / light shelves, particularly during the central hours of the working day. Once again it is a matter of achieving an optimum balance between reducing solar gains and enhancing daylight quality.

Key

vertical louvres

upper horizontal louvres

lower horizontal louvres

room ? facing W

room 11 facing SW room 5 facing E room 10 facing SE

Figure 82.  Shading devices for typical floor

Case study: St Andrew’s House, Glasgow

48


4.10.2. Implementing natural ventilation through the introduction of an atrium As already discussed, deep plans are not suitable for cross ventilation. With that regard, the introduction of an atrium can dramatically improve the effectiveness of natural ventilation strategies. A schematic comparison of the two ventilation strategy is here drawn: - Single-sided ventilation is generally not very effective. Although it can normally meet the basic requirements for office occupancy, it heavily relies on external weather conditions (e.g. on wind speed, as discussed on Section 4.5.1 on page 29). That is particularly problematic during a hot summer, as previously seen in the future climate scenario, when a great the amount of heat needs to be exhausted. - Stack ventilation, with thermal buoyancy generating pressure differences that drive the air up along the atrium and out of the stacks on top of it. If the top of the atrium is glazed and carefully designed to maximise solar gains, the stack effect can be enhanced by what is called ‘solar chimney effect’. Solar gains adds to heat of the air the top of the atrium, amplifying the difference in temperature between incoming and out-flowing air, resulting in a more effective draw of air through the building.

ROOF

ROOF

L17

L17

L16

L16

L15

L15

L14

L14

L13

L13

L12

L12

L11

L11

L10

L10

L9

L9

L8

L8

L7

L7

L6

L6

L5

L5

L4

L4

L3

L3

Figure 84.  Cross section showing the existing scenario: singleside ventilation

Case study: St Andrew’s House, Glasgow

Figure 85.  Cross section showing the existing scenario: natural ventilation is enhanced by the stack effect introduced by the atrium

49


4.10.2.1. Arranging the internal layout for natural ventilation and daylight It can be observed that in order to benefit from improved daylight levels and natural ventilation strategies, the introduction of a central atrium becomes effective only when combined with an open plan layout. Internal partitions might be preserved, but they should not obstruct the flow of air across the floor plan. For that reason, if ventilation is supplied by top window panes, partitions should not reach the ceiling height.

Figure 86.  Floor plan is arranged to optimise natural ventilation and access to natural light Key

workstation areas with high daylight factors

workstation areas with satisfactory daylight factors

natural ventilation

The layout illustrated on Figure 86 aims to represent a potential solution to combine the passive strategies that have been discussed. It is not intended as a complete resolution, that only a full design process could achieve, but rather a graphical synthesis of the considerations just described.

Case study: St Andrew’s House, Glasgow

50


5. Case study: Argyle House, Edinburgh


5.1. Argyle House, Edinburgh Argyle House is an office block located in the heart of Edinburgh, at the crossing between Lady Lawson Street and King’s Stables Lane. Designed in 1961 by Michael Laird Architects, it was at the time one of the first mid-rise modern buildings in the city centre; its massing and its proximity to the Edinburgh’s Castle made it a prominent landmark ever since. The building is articulated in different parts: two 11-storey office blocks (7 of which over ground), denominated block A and block B, similar in plan and with specular orientation; the north-block that functions almost as a podium for castle terrace elevation at northwest (see Figure 89 below).

Figure 87.  Bird-eye view (adapted from Microsoft, 2012a) Figure 88.  Location plan (adapted from Edinburgh City Council, 2010)

Figure 89.  Site plan with indication of the building’s parts (adapted from Swift and Partners, 1961)

Case study: Argyle House, Edinburgh

52


5.1.1. Building typology The shallow plan structure reminds those of type 1 and type 2 buildings (BRE, 2000) as classified in Section 2.1 (see Figure 90). As already mentioned, the building falls into type C (Table 6) defined by the Office project (see Section 2.4). Because of its considerable height and the configuration of its site, the building is fairly exposed to the outdoor environment: as a consequence the outer skin is expected to play big role in the overall energy performance of the building. The building fabric is overall quite massive: floors and ceiling are made of in situ concrete and external cladding with prefabricated concrete panels (Figure 95 on page 54). The plan has a quite articulated structure, which is inconsistent from floor to floor, as a result of patterns of use overlaid for over 40 years. The two main blocks of office space are connected via a central core of services (or ‘Link’). The office space is open plan at some floors and cellular in some others. For block A for instance, floor F (1st level) has a pretty linear open plan layout while floor K (4th level) has a series of enclosed office spaces facing south (see APPENDIX D for details). For the purpose of the analysis, only the portion above ground level of blocks A and B will be considered, corresponding to levels E to M.

degree of exposure Free standing Type C

X

enclosed

thermal mass heavy

light

X

skin dependence

internal structure

Skin dep.

Open plan

X

Core dep.

cellular X

Table 20.  Characteristics for type C buildings (adapted from Dascalaki and Santamouris, 2002).

10-20m 4-10m

up to 18m

Figure 90.  Average sizes and plan structures for buildings from Type 1 (above) and Type 2 (below) (adapted from BRE, 2000)

Figure 91.  Floor F (Level 1) plan (adapted from Laird, 1966)

Case study: Argyle House, Edinburgh

53


5.1.1.1. Existing issues: low floor height 282.25 1450 and elevated air leakage Like many buildings of the same era and typology, the floor-to-floor height is very problematic for Argyle House. As Figure 94 shows, the floor-to-ceiling height is further reduced to approximately 2.5 meters, due to 272.75 1160 the detrimental presence of suspended ceilings, inconsistently from floor to floor. As it will be assessed by the analyses, this issue prevents from a good daylight penetration (particularly for the open plan layout) and it originates constraints to natural ventilation strategies.

301.25 2030

ROOF

291.75 1740

L6

FLOOR M

282.25 1450

L5

FLOOR L

272.75 1160

L4

FLOOR K

263.25

870

L3

FLOOR J

253.75

580

L2

FLOOR H

244.25

290

L1

FLOOR F

234.75

00

L0

FLOOR E

225.25 -290

L-1 FLOOR D

215.75 -580

L-2 FLOOR C

It is interesting to note that, even if the external cladding is not in the same derelict conditions as the previous case study, still it performs very poorly. The detailed section gives good Figure 92.  Cross section (adapted from Laird, 1966) information about the constructive system in use (Figure 95). The lack of insulation, albeit evident, is not any more prejudicial for winter performance than the deficient air tightness. As the 3½” external aggregate finish panel is bound (presumably by mortar) to a 3” breeze block built on site, awkwardly tapered at the top for the purpose, there seem to be no credible technology to stop air infiltration. 206.25 -870

250cm

270cm

Case study: Argyle House, Edinburgh

F

L4

F

180cm 80cm

Figure 94.  Enlarged view of the cross section showing the height of a typical floor (adapted from Laird, 1966)

L-3 FLOOR B

Figure 95.  Detail of the existing cladding system (Laird, 1966) Figure 93.  Cross section (Laird, 1966)

L5

Potential weak points for air leakage are highlighted.

54


5.1.2. Open plan and cellular office layout As already discussed in the previous case study, different layouts lead to fairly different thermal performances and daylight distributions.

BLOCK B

For the purpose of simulations, two scenarios are modelled: 1) The typical floor structure, which is the same on every level, consists of three main open plan office spaces, two in block A and one in Block B. Minimum space is given to corridors and some meeting rooms are located at the margins, next to the stairs (Figure 96). The detailed analyses will focus on the open plan space on block A, identified as room 016.

x BLOCK A

stairs and elevators conference rooms

Figure 96.  SketchUp model of first scenario: open plan layout for typical floor

open plan space

2) The typical floor plan comprises a set of enclosed rooms, that serve both as offices and meeting rooms (Figure 97). They are distributed along three main corridors that develop from the core (or ‘Link’). Results from both north facing and south facing offices on block A will be discussed.

BLOCK B

BLOCK A

stairs and elevators corridors cellular offices

Case study: Argyle House, Edinburgh

Figure 97.  SketchUp model of second scenario: cellular layout for typical floor

55


5.2. Winter thermal performance and annual energy consumption 5.2.1. Open plan A first assessment of winter performance is carried on with the assumption of open plan offices at every floor (Figure 98). Parameters for the simulation are listed in Table 21. The analysis shows a quite elevated heating plan sensible load (Figure 100), caused from heat losses that derive both from the poor insulation of the existing fabric and the high contribution of infiltration. Compared to the first case study this building has a very shallow plan. Hence, as discussed, the outer skin has a greater impact on the overall building performance. Moreover a large percentage of the façade is glazed and this determines the extremely poor U-value of single glazing alone (over 5 W/m2K) to be Table 21.  Simulation parameters for evaluating the baseline thermal performance (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Case study: Argyle House, Edinburgh

B2.01 try w xuv fc chr ncm min dod

highly detrimental for the overall performance. In that regard Figure 101, comparing heat losses through glazing to the equivalent solar gains during winter, is self-explanatory. As a result, the annual energy consumptions are fairly high, as Table 22 shows.

Figure 98.  First scenario modelled in IES SketchUp plugin. The room under focus (room 14) is highlighted in red.

ROOM 14

Table 22.  Annual energy consumption for St Andrew’s House baseline scenario

Baseline annual electrical consumption: 66.8 kWh/m2.yr 61.7 kgCO2/m2.yr Baseline annual thermal consumption: 234.7 kWh/m2.yr 42.3 kg CO2/m2.yr

Figure 99.  Annual energy consumption for St Andrew’s House baseline scenario

Figure 100.  Heating plant sensible load for baseline situation

electrical; 22%

thermal; 78%

Figure 101.  External solar gains and conduction losses for room 14

56


5.2.2. Cellular

Figure 102.  Annual thermal energy consumption breakdown

The analysis is run with the same parameter for cellular layout (Figure 103). Results are pretty similar to the open plan situation, in terms of heating loads and energy consumption (see Table 23 below). Minor differences are ascribable to different light and thermal requirements of corridors as opposed to office space (e.g. lower illuminance levels or heating set point). If the results are compared with those reported on Section 2.4, it can be observed that energy consumptions for Argyle House sits in between those of Type C buildings for Mid Coastal and North Coastal climates (Figure 104). Once again this result should not be looked at as an accurate estimate of the building’s consumption but rather a confirmation of the hypotheses initially made.

Figure 103.  Second scenario modelled in IES SketchUp plugin. The rooms facing south are highlighted in red.

Table 23.  Annual energy consumption for Argyle House - baseline scenario

Baseline annual electrical consumption: 52.6 kWh/m2.yr 48.6 kgCO2/m2.yr Baseline annual thermal consumption: 244.6 kWh/m2.yr 44.0 kg CO2/m2.yr

Case study: Argyle House, Edinburgh

Argyle House Figure 104.  Energy consumption for Argyle House in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)

57


5.3. Daylight 5.3.1. Open plan The average daylight factor (Table 24) is satisfactory for office activities. Nevertheless the value is approximate and takes no account of the actual distribution of light.

room 06

As a matter of fact the proportions of the rooms, particularly the low floor-to-floor height previously discussed (see Figure 94 on page 54), are such to prevent a satisfactory daylight penetration. Therefore while good average daylight factors are achieved, the rooms are too deep to be successfully day lit. As Figure 106 shows the central area of the floor plate is below the recommended value of 300lux (Kaufman, Christensen and IES, 1987).

Figure 106.  Area below the threshold value of 300 lux

Case study: Argyle House, Edinburgh

room 16

room 18

Figure 105.  Filled contour daylight factor for typical floor

Table 24.  Daylight calculation results for the open plan areas typical floor

Uniformity min / avg

Diversity min / max

6.7 % 32.3 % 823.9 lux 3942 lux

0.02

0.00

0.1 % 7.05 lux

7.3 % 34.2 % 896.7 lux 4179 lux

0.01

0.00

0.4 % 45.9 lux

7.2 % 36.4 % 881.6 lux 4445 lux

0.05

0.01

Location

Quantity

room 06

Daylight Factor DL illuminance

0.1 % 13 lux

room 16

Daylight Factor DL illuminance

room 18

Daylight Factor DL illuminance

min

values avg

max

58


5.3.2. Cellular The cellular layout does not perform better in terms of absolute illuminance values, but the minimum values reached within the cellular offices are higher than the equivalent open plan (Table 25). This is due to a lower depth of the office spaces, that are assumed to be separated from the corridor by means of opaque partitions. It is important to observe that, as a consequence, the daylight uniformity of each rooms is generally quite higher, and included on average between 0.1 and 0.15.

room 57 room 54

room 48

Figure 107.  Filled contour daylight factor for typical floor

Table 25.  Daylight calculations for some cellular offices on typical floor. The cellular structure is the reason for a better DL uniformity.

Case study: Argyle House, Edinburgh

min

values avg

max

Daylight Factor DL illuminance

0.9 % 108.8 lux

7.4 % 900.5

room 54

Daylight Factor DL illuminance

room 48

Daylight Factor DL illuminance

Location

Quantity

room 57

Uniformity min / avg

Diversity min / max

26.4 % 3230 lux

0.12

0.03

0.7 % 88.8 lux

6.8 % 26.4 % 832.1 lux 3219 lux

0.11

0.03

0.7 % 90.5 lux

8.1 % 26.4 % 993.5 lux 3230 lux

0.09

0.03

59


5.4. Revised annual energy consumption As it has been observed, the cellular structure benefits from a better distribution of daylight, compared to the open plan structure. What is more, the very shallow floor plan permits a fairly deeper light penetration than for the first case study, despite a lower floor-to-ceiling height. Since the assumptions on the use of artificial lighting have been the same for both the case studies, it seems appropriate to adjust them, to acknowledge different baseline conditions. A similar parallel can be drawn regarding air tightness. The inadequacy of external cladding system to keep the building thermally insulated and airtight has been pointed out (Section 5.1.1.1 on page 54). As a result, air leakage is expected to greatly exceed the assumptions made for the purpose of thermal simulations. Accordingly, artificial lighting levels are reduced by an estimated 30%, to account for the increased reliance on daylight, compared to the first case study. At the same time, the value of airtightness is increased from 10 to 25 m3/hm2 at 50Pa, as suggested by McHard (see Section 3.2.3). The updated parameters produce a significant change for the annual energy consumptions (see Table 27 and Figure 108) highlighting the differences with the previous case study (see Figure 35 on page 27). Case study: Argyle House, Edinburgh

Table 26.  Simulation parameters for evaluating the baseline thermal performance (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

B2.01a try w xuv fc chr mat min dod

Table 27.  Revised annual energy consumption for Argyle House baseline scenario

Revised annual electrical consumption: 37.1 kWh/m2.yr 33.7 kgCO2/m2.yr Revised annual thermal consumption: 355.3 kWh/m2.yr 65.8 kg CO2/m2.yr electrical; 9%

thermal; 91%

Figure 108.  Energy consumption for Argyle House as result of adjusted parameters, in comparison to five building types from Office project (adapted from Dascalaki and Santamouris, 2002)

Argyle Argyle 1st 2nd simul. simul. 60


5.5. Summer thermal performance Measured and perceived thermal comfort The results just obtained contrast with direct experiences. According, for instance, to Stephen The results from the simulation, performed with McHard (see Section 3.2 on page 16) who parameters listed in Table 29, are represented moved in Argyle house during the 1980s, at in Figure 109. It appears that the maximum air summer the workplace was “an oven”. This temperatures fluctuate between 22° and 24°C confirms the assumption that the lack of during the month of July. As the temperature summer comfort depends on more than just one of 28°C is never reached, it would be correct variable, namely air temperature, as Figure 110 to assume that the building does not overheat suggests. (CIBSE, 2006). The Predicted Mean Vote, an index that expresses a measure of comfort based This example represents a ‘cautionary tale’, exposing how even the most sophisticated on the 7-point thermal sensation scale (from thermal analysis tools often cannot account for -3:cold to +3:hot) (ASHRAE, 2004), seems to Figure 110.  Causes of summer discomfort for a workplace: the complexity of real scenarios. point out that discomfort is due rather to cool pollution from equipment, smoking and direct solar radiation on occupants (adapted from Rennie and Parand, 1998) mornings than to daily heat (Table 28).

5.5.1. Open plan

Table 28.  Predicted Mean Vote (PMV) for the month of July

PMV – hours in range < -1

-1 to -0.5

0

136

-0.5 to 0 0 to 0.5 0.5 to 1 58

16

0

Table 29.  Simulation parameters for baseline situation

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Case study: Argyle House, Edinburgh

B2.02 try s xuv fc nv ncm dv dod

Figure 109.  Summer air temperature for room016 in Block A (dark green), outside dry-bulb temperature (green/cyan)

61


5.5.2. Cellular Unlike the winter scenario, the difference with the open plan layout is quite pronounced during summer. Particularly in Block A, south-facing offices receive higher solar gains than northfacing offices (Figure 111), resulting in higher summer temperatures. As a consequence, temperatures in south-facing cellular offices are often one degree higher than in north-facing ones and get up to two degrees hotter than the open plan equivalent (Figure 112). With current weather data a cellular layout instead of an open plan does not affect summer thermal comfort significantly. However when the tests will be performed with data based on future weather predictions, the discrepancy is expected to increase much more. Different plan typologies in fact, cause divergent behaviour in terms of solar gains and natural ventilation in a hot summer scenario.

Case study: Argyle House, Edinburgh

Figure 111.â&#x20AC;&#x192; Solar gains in comparison: north-facing office (yellow) and south-facing one (red)

Figure 112.â&#x20AC;&#x192; Air temperatures in comparison: summer temperature in south-facing cellular offices (red), north-facing cellular offices (green) and open plan (yellow). Dry-bulb outside air temperature in cyan.

62


5.6. Summer thermal performance: future scenarios.

Figure 113.  Summer dry-bulb outdoor air temperatures for simulations B2.02 (green) and B2.03 (red) in comparison

As anticipated in the research methodology (Section 3.4), it seems interesting to evaluate the building’s performance under future climate scenarios. The parameters for thermal simulation are updated to the ones in Table 30. As opposed to the scenario illustrated in Section 5.5.1 on page 61, where the temperature of 25°C was never reached, with the new weather data temperatures rise well over 25°C. As Table 31 reveals, with a future climate scenario elevated indoor temperatures are reached for a considerable number of occupied hours, Figure 114.  Tested rooms at floor K (level 4) resulting in a very uncomfortable working environment.

Table 31.  Summer indoor air temperatures for different simulations - climate data

Air temperatures

001 003

Location room 006

Table 30.  Simulation parameters for future climate projections (see APPENDIX A for details)

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

Case study: Argyle House, Edinburgh

B2.03 E 2050 hi 90p - dsy s xuv fc nv ncm dv dod

room 018

room 016

010

015

Room 015 Room 016 Room 006 Room 004 Room 003 Room 001 Room 019 Room 010 Room 021 Room 005 Room 018 Total hours

TRY > 25°C 0 0 0 0 0 0 0 0 0 0 0 0

2050hi 2050hi 90p DSY 90p DSY > 25°C 99 89 90 87 97 97 88 91 87 101 87 1013

> 28°C 38 34 34 35 40 36 34 35 34 37 34 391

63


5.6.1. Occupant density in future scenarios As for Argyle House, floor plan furniture layouts that were produced as part as proposed redevelopment from different letting agencies (Argyle House, 2011) demonstrate the intention to consolidate workplaces densities and possibly set them higher. As Figure 115 shows, the area comprised in the width of one structural bay, approximately 4,60 m, and half the depth of the floor plan (circa 6,5 m) has an area of 25,25 m2 and it is organised to host 6 users. This corresponds to a localised density of circa 5 m2/person; taking into accounts corridors and areas with larger percentage of equipment and furniture it can be concluded that the assumption of 6 m2/person can be fairly precise. This confirms the assumptions initially made by McHard (see Section 3.2.4 on page 17).

Case study: Argyle House, Edinburgh

6,52m axe of symmetry

4,57m

Figure 115.â&#x20AC;&#x192; Floor K plan _ scale 1:50 (adapted from Argyle House, 2011)

Figure 116.â&#x20AC;&#x192; Workplace redevelopment renderings (Argyle House, 2011)

64


5.6.2. Evaluating the impact of occupant density The results that were produced from all the simulations performed, have been affected to a great extent by the quality of assumptions made. To analyse the effect of increased occupant densities a series of 3 simulations is performed. Considering a future climate scenario, it will be assumed that the building facades has been recladded: updated U-values for both opaque and glazed constructions will be considered, together with an up-to-standard airtightness (Table 33). The assumptions made so far, in terms of internal gains, are the ones summarised in Table 32.

Table 32.  Baseline internal gains parameters

Simulation B2.04 Lighting: Office equipment: People: Occupant density:

Max sensible gain 11.25 W/m2 10.76 W/m2 73.27 W/person 11.6 m2/person 6.32 W/m2

Max latent gain

Simulation B2.05 Lighting: Office equipment: People: Occupant density:

Max sensible gain 11.25 W/m2 15.6 W/m2 73.27 W/person 8 m2/person 9.16 W/m2

Max latent gain

Simulation B2.06 Lighting: Office equipment: People: Occupant density:

Max sensible gain 11.25 W/m2 20.77 W/m2 73.27 W/person 6 m2/person 12.21 W/m2

Max latent gain

Figure 117.  Incidental heat gains in comparison

20 Key

10 5 0

Case study: Argyle House, Edinburgh

5.05 W/m2

58.61 W/person 7.32 W/m2

58.61 W/person 9.77 W/m2

8am-6pm / M-F Variation profile 8am-6pm / M-F 8am-6pm / M-F

8am-6pm / M-F Variation profile 8am-6pm / M-F 8am-6pm / M-F

8am-6pm / M-F

Table 33.  Simulation parameters for increased occupant density (see APPENDIX A for details)

25

15

58.61 W/person

Variation profile 8am-6pm / M-F 8am-6pm / M-F

lighting gain

equip. gain B2.04

equip. gain B2.05

equip. gain B2.06

people gain B2.04

people gain B2.05

people gain B2.06

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Simulation parameters Occupant density Simulation parameters Occupant density

B2.04 E2050 hi90p _DSY s nuv fc nv iat dv dod B2.05 oc8 B2.06 oc6

65


The internal gains deriving from people and equipment are proportionally increased, while the gains from artificial lighting are maintained, assuming that the requirement of 300 lux is constantly provided.

Figure 119.  Summer air temperatures for increased occupant densities on a weekly basis

The results show an increase of air temperature that reaches over 1°C: while this delta is not impressive, it can still be a reason for concern, particularly on a hot summer day (Figure 120). The effects of increased density on the indoor working environment can also be appreciated with regards to CO2 concentration values (Figure 118).

Figure 118.  CO2 concentrations for increased occupant densities

Case study: Argyle House, Edinburgh

Figure 120.  Summer air temperatures for increased occupant densities on a daily basis

66


5.7. Retrofitting scenarios: building envelope 5.7.1. Summer solar gains 5.7.1.1. Reduce windows area If we consider the floors that have an open plan layout, then a good level of flexibility is offered for the number of external openings. Reducing external glazing is possible without drastically compromising the visual comfort. On the other hand where the layout is cellular, the reduction of opening can be problematic, particularly for smaller rooms that have limited access to daylight. Argyle House has an elevated glazing ratio (see Figure 121), which is the same for north and south elevations. It might be appropriate to operate a selective reduction of glazed area, to take full account of the solar radiation.

5.7.1.2. Internal or mid-pane blinds Internal or mid-pane blinds have been discussed for the previous case studies and proved to be cost-effective solutions only when retaining the existing façade.

5.7.2. Air leakage and insulation levels The very poor performance of the external cladding system as well as of the existing glazing have been extensively discussed. As a consequence the use of systems such as internal double-walls is considered redundant and ineffective, if compared with a full façade recladding. The chance of weather stripping external windows is here not considered.

5.7.3. Façade removal and recladding To approach façade removal and recladding, it is important to fully understand the technology and constructive systems that were originally adopted. They represent the boundary conditions that shall inform and address design choices. As for the present building the outside panels follow a three-bay span, the same as the structure (Figure 122 below). An analysis on the floor plan can be linked with a visual analysis on the elevations, where one out of three ribs hides a joint, with the other two showing false joints (Figure 123). Figure 122.  Floor plan (adapted from Laird, 1966) R2

R2

Figure 121.  Argyle House, north-west elevation (Parnell, 2011b)

R1

Case study: Argyle House, Edinburgh

R1

67


As a consequence a successful recladding shall follow the baseline structural module, with the possibility to vary opaque and transparent surfaces according to the building’s needs.

W

R1

R2

Figure 124.  Detailed section of the existing façade, showing the cladding system (Laird, 1966) R1

R2

P3

P3 P1

B

P2 P1

Key

B

R2 ribs hide false joints R1 ribs hide cladding joint P1 P2 P3 cladding panel’s components W two pane windows B 3” breeze block

Figure 123.  Zoomed elevation for visual analysis of the cladding system (adapted from Parnell, 2011a). Sealing is visibly different from panel to panel.

Case study: Argyle House, Edinburgh

Figure 125.  Axonometric exploded of the existing cladding system.

68


5.8. Retrofitting scenarios: HVAC system

pump (default SCoP of 2, set by the software) is Table 34.â&#x20AC;&#x192; Simulation parameters for evaluating the HVAC scenario (see APPENDIX A for details) chosen (Table 34).

HVAC systems are not included in the scope of the present research. Moving the focus onto them has the sole purpose of establishing the boundary conditions that define the architectural research.

As it can be observed, the change would result in a radical reduction in CO2 emissions for thermal consumption but at the same time a significant rise in electrical consumption, to feed the air source heat pump.

It is relevant to point out that all the results obtained so far, in terms of energy consumption, depend on the assumption of a central heating system, using radiators with a Seasonal Coefficient of Performance (SCoP) set at 0,89. Section details seem to confirm the presence of radiators (Figure 124 on page 68), although the SCoP has not been estimated but rather assumed as the software (IES Apache) default. In terms of retrofitting interventions, the impact on a Building Management System is not investigated. The system efficiency, however, can be increased in different ways. Any recladding actions would certainly involve the removal of the outdated radiators, which are integrated into the existing cladding (Figure 124). At the same instance the existing boilers, obsolete and poorly performing, are in need of replacement. A simulation is performed to assess the impact that a radical change of heating system would have on the overall consumptions. An underfloor heating fed by a air-source heat

Case study: Argyle House, Edinburgh

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

B2.07 try w xuv fc uhp ncm min dod

Table 35.â&#x20AC;&#x192; Annual energy consumption for Argyle House - HVAC scenario compared to baseline

Baseline system (central heating radiators) Annual electrical consumption:

Annual thermal consumption:

66.8 kWh/m2.yr

234.7 kWh/m2.yr

61.7 kgCO2/m2.yr

42.3 kg CO2/m2.yr

Underfloor heating with air-source heat pump Annual electrical consumption:

Annual thermal consumption:

170.7 kWh/m2.yr

5.7 kWh/m2.yr

157.7 kgCO2/m2.yr

1.0 kg CO2/m2.yr

69


5.9.2. Improvement of daylight 5.9. Retrofitting scenarios: lighting systems and use of daylight 5.9.2.1. Light shelves

5.9.1. Lighting system efficiency Decreasing the general lighting level is a fairly simple operation to achieve energy savings. The energy consumptions discussed in the case study derived from simulations that assumed a general illuminance level of 500 lux. Cutting down the value to 300 lux can still be considered satisfactory, if the lighting appliances are implemented with localised task lighting. Such an action would result, according to the calculations performed, in cutting down the annual electrical consumption by 10-15%.

As it has been discussed in the previous case study, light shelves are rarely effective for buildings with floor-to-ceiling heights inferior to 3 meters. This is the case for the present building (see Figure 94 on page 54) , where the installation of light shelves would likely result in a reduction of illuminance levels without improving its uniformity considerably.

Sensors and time-scheduled control of lighting are also major contributors to electrical energy savings. However they require the installation of a Building Management System, which represents a considerable initial investment. The rearrangement of internal layout can also produce some micro-scale zoning, gathering areas with different illuminance requirements and paving the way for selective reduction of illuminance levels.

Case study: Argyle House, Edinburgh

70


5.9.2.2. Internal office layout and access to daylight

Figure 126.  Block A, Floor F plan _ existing layout. The area below 300 lux is hatched in green.

With regards to the strategy discussed in Section 5.9.1 it can be observed that the layout of the workplace has a notable impact on daylight penetration. With a rather low ceiling such as the one from the present case study (Figure 94), daylight penetration is limited. As a consequence the central area of the floor plan, roughly included between the two central rows of structural columns, falls below the medium recommended value of 300 lux. The existing layout for a typical floor (Figure 126) was presumably designed taking full account of daylight access: workstations are placed next to perimeter windows and a central corridor is Figure 127.  Block A, Floor F plan _ proposed layout (adapted from Argyle House, 2011). used for distribution. This pretty simple and rational criterion was unfortunately neglected in one of the proposed layouts (Argyle House, 2011). Here the ‘optimization’ of occupancy, aimed at achieving a more efficient use of rentable area, has produced a result that in terms of daylighting is not efficient at all (Figure 127). Two rows of workstations are introduced where natural light cannot alone satisfy the visual comfort requirements. For such a layout the strategy of decreasing the lighting levels discussed in Section 5.9.1 is not practicable, as it would result in visual discomfort. The red dashed line indicates the workstation ares that sits below the the minimum recommended value of 300 lux.

Case study: Argyle House, Edinburgh

71


5.10. Retrofitting scenarios: passive systems and techniques

removing the false ceilings (FC) and exposing the concrete slab (XC) results in a moderate subtraction of heat from the room, that does not affect the air temperatures notably when the 5.10.1. Passive solar External shading devices have been investigated workplace is occupied (Figure 128). for the previous case study, for the south, south-east and south-west façades. The study will not be repeated here, in the belief that the information gathered in Section 4.10.1.1 would be sufficient to inform the design of shading devices for Argyle House.

5.10.2. Thermal mass

A series of numerous simulations is performed to assess the effects of exposing thermal mass for the building under analysis. Firstly tests are run with refurbished envelope U-values and airtightness (same as Section 4.7.2.2). Two simulations are done with the same parameters, except for the floors and celings construction (Table 36). The results show that

Case study: Argyle House, Edinburgh

Simulation parameters Climate data Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density Simulation parameters Floor ceiling type

5.10.2.1. Exposing thermal mass As it has been observed with the first case study, daytime ventilation cannot alone exhaust the excess heat, especially when the outdoor air temperature is too high (i.e. above 24°C). Moreover, air movement is often subject to unpredictable weather conditions and it can lead to uncomfortable indoor conditions.

Table 36.  Simulation parameters for suspended ceilings (above) and exposed concrete ceilings (below) (see APPENDIX A for details)

B2.08 E 2050 hi 90p - dsy s nuv fc nv iat dv dod B2.09 xc

XC FC

FC XC

Figure 128.  Air temperatures (red and green) and ceiling conduction gains (yellow and pink) for suspended ceilings (FC) and exposed concrete ceilings (XC) in comparison. Infiltration in blue.

72


Table 37.  Parameters for iterative testing on thermal mass and night ventilation (see APPENDIX A for details) Note: where not specified, the parameters used for simulations B2.12, 13, 14 are the same as for simulation B2.11

Simulation parameters Climate data

B2.10 E 2050 hi 90p - dsy s nuv xci nv iat dv dod

Season scenario External envelope values Floor ceiling type HVAC system Air tightness Ventilation Occupant density

B2.11 xci dv+niv

Simulation parameters Floor ceiling type Ventilation

B2.12 xtci dv

Simulation parameters Floor ceiling type Ventilation

25 15

Simulation parameters Floor ceiling type Ventilation

B2.13 xtci dv+niv

5.10.2.2. Introducing night ventilation Night ventilation should be targeted at the ceilings: as fresh night air gets in, hitting the concrete slab that is left exposed after the removal of false ceilings, it flushes away the heat that has been stored during the day. As discussed in Section 2.3 the night cooling potential in the UK is considerable. For this reason the two-pane windows are redesigned (see Figure 137 on page 76) so that the upper pane, located above eye level, can be automatically operated at night, under the control of a Building Management System (BMS), to purge heat stored during the day. The simulation parameters are set as an opening formula that considers indoor and outdoor air temperature, simulating the use of BMS based on thermostats. Windows will open when the indoor air temperature will be greater than 25°C and the outdoor temperature less than 24°C. Moreover, the BMS should be set to close the windows when the outdoor

temperature falls below a minimum value (e.g. 15-16°C), to avoid excessive cooling that would determine unpleasant temperatures on the following morning. Wind speeds should also be monitored, to prevent gusts of wind to come into the building and blow paper.

5.10.2.3. Effects of thermal mass and night ventilation The effects of thermal mass are analysed for three different constructions: • Existing suspended ceiling / carpet floor on screed (Figure 129) • Exposed concrete ceiling / raised access floor (Figure 130) • Exposed concrete ceiling / raised access floor with underfloor insulation (Figure 131) • Exposed concrete ceiling of increased thickness / raised access floor with underfloor insulation

FALSE CEILING

Case study: Argyle House, Edinburgh

25 15 25 15

RAISED ACCESS FLOOR

Figure 130.  XC _ Exposed concrete ceiling

15 15

25 15

21.5 25 6.5 21.5 25 6.5

Figure 129.  FC _ Existing ceiling/floor layers

Figure 131.  XCI _ Exposed concrete ceiling with underfloor insulation

73


The use of four different construction types (the existing and the three ‘variations’ of the exposed ceiling) are intended to assess the impacts that the use of insulation layers and different slab thicknesses have on thermal performance, compared to night ventilation. As it can be observed from Figure 132, it is only when night ventilation is introduced that the benign effect of thermal mass (represented as heat losses from the room to the ceiling) becomes relevant. As a matter of fact, the benefits of using an increased slab thickness (XTCI) are not as appreciable as expected. Figure 132.  Ceiling conduction gains in comparison for working week 17th-21st July: XC without night ventilation (blue), XCI with night Finally it is interesting to mention the effects ventilation (red) and XTCI with night ventilation (pink) caused by the addition of underfloor insulation, which is necessary since every floor represents XC XCI a different ‘thermal unit’, with different patterns of use and perhaps independent heating profile. As Figure 133 shows, to a reduction of the heat sink capacity for the floor corresponds an increase for the ceiling. That becomes much without night ventilation more pronounced after the introduction of night ventilation, which is once again decisive for improving the thermal performance. XCI

XC RIGHT Figure 133.  Ceilings and floor conduction gains for 20th July. XC and XCI ceilings (red and pink); XC and XCI floors (blue and cyan) The beneficial effects of thermal mass can be appreciated when they are most needed: during the warmest hours of a typical summer day the exposed concrete slab (pink) can subtract up to 15KW from the room.

Case study: Argyle House, Edinburgh

with night ventilation

74


5.10.3. Implement forms of natural ventilation, adapting the internal office layout As already discussed, shallow plans are suitable for cross ventilation. However, some layout could be less or more suitable to fully benefit from natural ventilation. A micro-scale environmental zoning could improve the indoor climate situation. On the existing scenario daytime ventilation is provided by opening the perimeter windows. Those comprise two panes, of which the lower is fixed and the upper, and larger, opens tophung (Figure 136 on page 76). Ventilation happens just above the working plane, likely causing papers to blow and fading towards the centre of the floor plate as it meets obstacles on the way. By gathering common office appliances (e.g. photocopier, fax) or common areas (e.g. areas for small meetings, coffee tables, hot drinks machine) some small-scale environmental zoning can be implemented. By freeing up the areas from partitions and thus minimising resistance, corridors for natural ventilation can be created.

Figure 134.â&#x20AC;&#x192; Floor F plan _ cross ventilation on existing layout Figure 135.â&#x20AC;&#x192; Floor F plan _ cross ventilation strategies implemented for the proposed layout. Corridors for NV are hatched in orange.

Case study: Argyle House, Edinburgh

3

1 2

3

75


The existing windows can be replaced with more sophisticated ones. A single-type can be replaced with three different ones, to allow a more diverse and flexible use of natural ventilation (Figure 137, Figure 138):

To allow a greater flexibility without fully compromise the implemented ventilation strategy, the windows from type 3 could be replaced by type 2, to allow the layout to change and adapt during the building’s lifetime.

1. Typical window The upper pane is automatically controlled by a BMS system and it opens bottom-hung, activated by temperature or CO2 concentration sensors, to provide a continuous flow of air that does not interfere with office work. The BMS shall control operate the pane to provide night ventilation as well. 2. Typical window The lower pane is side-hung and it can be operated by the occupants, who can thus exert a high level of control on their indoor thermal conditions. 3. Window on the NV corridor The lower pane opens side-hung and bottomhung and it can be operated either manually (both during the day and the night) or automatically (for night ventilation), providing a stronger flow of air to exhaust summer heat without hitting desks and blowing papers.

Figure 136.  NV with existing window Figure 138.  Implemented NV strategies with new corridor window

Figure 137.  Implemented NV strategies with new typical window

1

3

2

This diversification would bring the benefits of a much more efficient natural ventilation strategy. On the other hand, combining different types of openings with spaces purpose-designed for NV would limit the flexibility of the internal layout. Case study: Argyle House, Edinburgh

76


5.10.3.1. Existing north and south elevation

Case study: Argyle House, Edinburgh

77


5.10.3.2. Proposed north elevation

Case study: Argyle House, Edinburgh

78


5.10.3.3. Proposed south elevation

Case study: Argyle House, Edinburgh

79


6. Conclusions


6.1. Research objectives

6.2.1. Building typology

This dissertation aimed to evaluate the potential carbon impact, and technical feasibility, of retrofitting office buildings in the UK. In order to test these aims, two buildings were carefully selected for an in-depth case study analysis, in order to provide useful and transferable information for two major non-domestic building typologies. Literature review has allowed to retrieve and distil information from analogous research, with comparable goals but much wider in scope. Passive retrofitting strategies and combinations of strategies were accurately tested, showing different degrees of effectiveness and feasibility for each.

As observed in the research carried out within the Office project framework, the building typology greatly affect energy consumptions. The case studies were intentionally selected as exemplars of the two building categories with the highest energy consumption (see Section 3.1).

6.2. Summary of findings The analysis of the baseline conditions has pointed out for the two buildings different patterns in terms of energy consumption. The research revealed similarities, but also some key discrepancies, between the potential impact of various retrofitting scenarios in the two buildings. The following subheadings explore this in light of building typology; occupant density and office technology; change of use, and passive measures scenarios.

The energy consumptions for St Andrewâ&#x20AC;&#x2122;s House, a deep plan building developed around a central core, were found to be high in terms of both thermal and electric energy. The defective state of its external cladding together with an outdated and inefficient heating system (based on current standards) were identified as the key reasons for its poor thermal performance. Despite having a good average daylight factor, the deep plan structure prevented adequate daylight penetration, increasing its reliance on artificial lighting and electricity consumption. The energy performance for Argyle House was found to follow a dissimilar pattern. Due a very shallow floor plan, particularly in the case of cellular office spaces the building benefits from satisfactory illuminance levels and better daylight uniformity. As a consequence, a less intense use of artificial lighting brings about lower electric energy consumption. The analysis on the building in Edinburgh found that the outer skin has a greater impact on thermal performance, if compared to St

Conclusions

Andrewâ&#x20AC;&#x2122;s House. This is partly due to distinct geometries, i.e. skin-dependent (type C) opposed to core-dependent (type A), as seen in Section 2.1. Furthermore, a careful examination on the existing cladding system reveals poor detailing. Discontinuities occur where prefabricated and in situ elements are combined and joined together, generating a presumably excessive air leakage that adds to the HVAC system loads. For both the case studies, in the light of the considerable heating loads that would be required, according to the analyses performed, it is legitimate to assume that energy consumptions have been reduced over the years at the expenses of internal comfort. The building envelope scenario has proved to be very effective in reducing heat losses. The analysis performed for the first building is valid for the second as well. Recladding is considered a cost-effective retrofit strategy for both of them. Considerations of the two structures and on the existing envelopesâ&#x20AC;&#x2122; technologies were presented to lead to coherent design choices. The impact of the retrofit on the lighting systems and use of daylight again raised both similarities and dissimilarities. The installation of sensors and time-scheduled controls controlled by a BMS, is feasible for both of them, despite representing a considerable initial investment. The two buildings can

81


accommodate a general decrease of lighting levels, on condition that task lighting is provided to meet minimum requirements. Their retrofit potential for passive measures, however, is fairly unequal. St Andrew’s House has the minimum floor-to-ceiling height (3 meters) required for the fruitful implementation of light shelves, to slightly help daylight penetration and improve uniformity. On the other hand, the low floor-to-ceiling height represent a serious constraint for Argyle House, giving it little space for improvement. The most cost-effective strategy appears to be to choose an open plan structure, arranging the layout to benefit from the good illuminance levels on the perimeter areas. For the first case study a strategy as intrusive as the relocation of the central core to make space for an atrium was evaluated. Due to the building’s latitude and the existing core’s constrained proportions, the results in terms of daylight improvement are not superlative. Possible solutions involve the use of the atrium for daylight only for the top 5-6 levels.

Conclusions

6.2.2. Occupant density and office technology The current trend has seen an increase in workplace density by over 30% in the last decade (see Section 3.2.4). What is more, office equipment has evolved considerably over the last few decades and the incidental gains that occur in a contemporary workplace are much higher than those of a 1960s building (e.g. with personal computers replacing typewriters). Simulations were performed to assess the effect of the increased incidental gains that a higher density of people and equipment would bring about. Results have shown reasons for concern, as the additional incidental gains add considerably to the cooling loads. The issue becomes more relevant if projected on the expected lifetime duration of the retrofitted buildings: with average temperatures projected to rise considerably, the cooling loads for St Andrew’s and Argyle House will become much greater that heating loads.

6.2.3. Change of use For St Andrew’s House a change of use has been discussed by evaluating benefits and drawbacks presented by the redevelopment into an hotel that the building has actually undergone. The same could be said about Argyle House, whose modular structure with repetitive bays could easily accommodate a simple layout of hotel rooms distributed along a central corridor. Such a change of use would cope better with the physical constraints of the building, particularly the reduced floor-to-floor height that is so problematic for an office space. Functions such as hotel host activities that are generally much less demanding in terms of daylight and can benefit from small-scale zoning (e.g. locating the bathroom at the dark end of the bedroom). Despite heating and cooling are provided for a shorter number of hours per day, however thermal comfort is generally measured accurately, and it is delivered to the end user like a finished product. This is why passive measures, that involve a degree of uncertainty and require the cooperation of building occupants, are usually looked at with scepticism. Functions that involve high turnover rates of occupancy would generally rely more heavily on active measures.

82


6.2.4. Passive measures and comfort in a future climate scenario The case studies have examined buildings that are located in a Mid Coastal - North Coastal climate. The use of Test Reference Year that gathers climatic data from 1961-90. In consideration of the buildings’ lifetime, which refurbishment is expected to prolong, the data used to date fails to accurately represent a future situation. Possible future climate scenarios has been embedded in the simulations by means of weather data generated according to the UK Climate Projections. The simulations performed on Argyle House have exposed the inadequacy of the building in its present state. Passive retrofitting scenario have been assessed and have been found successful in providing the buildings with the resources necessary to adapt to global warming. Passive solar strategies have proved to be highly effective. Fixed external shading devices can be designed to protect the façades from unwanted summer solar gains, without compromising the occupants’ outdoor visibility. Movable devices are particularly useful for shading the building when the sun angle is very low, i.e. in the early morning and late afternoon, also helping to prevent glare. However installation and maintenance is more expensive than for the fixed ones.

Conclusions

The improvement of natural ventilation was considered pivotal in order to deal with a future climate scenario. Passive measures retrofitting scenarios included a careful design of ventilation strategies, again with different outcomes. As for the first case study, it has been remarked that the cellular layout together with daytime single-sided ventilation is not at all effective as a cooling strategy. The introduction of a central atrium provides an effective stack ventilation, which can be enhanced by means of the ‘solar chimney effect’. As for the second case study, through the rearrangement of the internal layout together with a careful design of the external openings, the floor plan can be zoned in order to allocate cool areas or ‘corridors’ for natural ventilation.

slabs, if exposed, should provide a more pronounced thermal mass. It seems appropriate to dedicate a final consideration to indoor comfort conditions for the case studies: despite IES VE has the capability to calculate accurately comfort conditions, the study has not stressed the attention of indicators such as PPD or PMV. Theories on adaptive comfort, reported in Section 3.3, have demonstrated how the implementation of passive measures needs a looser definition of comfort conditions. Priority has been given to retrofitting measures that, together with sophisticated control systems, could provide occupants with a high degree of control over their internal environment.

For the two case studies the implementation of ventilation strategies has induced the replacement of cellular offices with an open plan layout, as the only layout that can coexist with natural ventilation strategies. The use of thermal mass has been evaluated for Argyle House, by means of removing the suspended ceilings and exposing the concrete slabs. Results show that in combination with a purpose-designed night ventilation strategy, the office rooms can benefit from a tangible ‘heat sink effect’ during the warmest hours af a summer day. The considerations are also valid for St Andrew’s House, where thicker concrete

83


6.3. Limitations of the present study and further research The cost-effectiveness of the proposed retrofitting strategies and scenarios is a vital consideration when evaluating the most appropriate level of intervention on an existing office building. While the retrofitting strategies were presented briefly in terms of the level of modifications induced, the cost-effectiveness of each was not deeply investigated.

This highlights a general problem with using two buildings in a similar climatic location for the case studies. It would have been better, with more time and resources, to have extended the case study approach to a range of building typologies in different parts of the UK.

As for the measures that have been discussed in the case studies, the potential retrofitting strategies have not included the use of doubleskin facade. While for Argyle House such a measure would potentially reduce or alter the cross ventilation potential, for the deep-plan St Andrewâ&#x20AC;&#x2122;s House this could replicate the stack effect generated by the introduction of the central atrium, improving considerably the ventilation strategy. Another limitation was the challenging nature of improving daylight penetration in a deep-plan building, by means of introducing an atrium. The analyses showed that geometric and climatic constraints greatly affected the proposed interventions, limiting its effectiveness. It would be interesting to perform the daylight simulations at different locations further south (e.g. London) to estimate if the improved climatic conditions (i.e. sky luminance) would bring about a considerable improvement in the performance.

Conclusions

84


References Action Energy (2003). Energy use in offices. “ECON 19” Energy Consumption Guide 19. London, UK: DETR. Available from: <http://www. energybenchmarking.co.uk/Offices/ECON19reprintMarch03.pdf> [Accessed 8th June 2012] Addy, N., and McCallum, P. (2012). Cost model: Office refurbishments. Building Magazine, 22.06.2012, 48-59. Anderson, J., and Mills, K. (2002). Refurbishment or redevelopment of office buildings? : sustainability comparisons. BRE Information Papers. Building Research Establishment. Argyle House (2011). Argyle House, A Remarkable Transformation. [Online brochure] Available from: <www.argylehouseedinburgh.com> [Accessed 25th July 2012] Artmann, N., Manz, H., and Heiselberg, P. (2007). Climatic potential for passive cooling of buildings by night-time ventilation in Europe. Applied Energy, 84(2), 187–201 [Online] Available from: <http://dx.doi.org/10.1016/j.apenergy.2006.05.004> [Accessed 6th June 2012] ASHRAE (2004) Standard 55-2004. Thermal environmental conditions for human occupancy. Atlanta, Georgia: American Society of Heating, Refrigerating and Air-conditioning Engineers. Brand, S. (1994). How building learn. What happens after they’re built. New York: Penguin Books. BRE (2000). Comfort without air conditioning in refurbished offices_ an assessment of possibilities. New Practice Case Study 118. Building Research Establishment. British Council for Offices (2009a). 2009 guide to specification : best practice in the specification for offices. London: British Council for Offices. British Council for Offices (2009b). Sharp increase in office density reveals today’s changing working environment. British Council for Offices. [Online] Available from: <http://www.bco.org.uk/news/detail.cfm?rid=118> [Accessed 25th July 2012] Brown, G. Z., & DeKay, M. (2000). Sun, Wind and Light: Architectural Design Strategies. 2nd ed. John Wiley & Sons. CIBSE (2004). Energy efficiency in buildings. London: CIBSE. CIBSE (2006). Environmental design: CIBSE guide A. London: CIBSE. Dascalaki, E., & Santamouris, M. (2002). On the potential of retrofitting scenarios for offices. Building and Environment, 37(6), 557–567 [Online] Available from: <http://dx.doi.org/10.1016/S0360-1323(02)00002-1> [Accessed 6th June 2012]


DeKay, M. (2010). Daylighting and Urban Form: An Urban Fabric of Light. Journal of Architectural and Planning Research, 27(1), 35. Available from: <http://works.bepress.com/cgi/viewcontent.cgi?article=1005&context=mark_dekay> [Accessed 8th June 2012] Department for Communities and Local Government (2008). National calculation methodology (NCM) modelling guide (for buildings other than dwellings in England and Wales). London: Communities and Local Government Publications. Available from: <http://www.communities.gov.uk/ documents/planningandbuilding/pdf/1016185.pdf> [Accessed 25th July 2012] Department for Communities and Local Government (2008). Zero carbon for new non-domestic buildings consultation on policy options. Available from: <http://www.communities.gov.uk/documents/planningandbuilding/pdf/1391110.pdf> [Accessed 17th July 2012] Dye, A., & McEvoy, M. (2008). Environmental construction handbook. London: RIBA Publishing. Eames, M., Kershaw, T., & Coley, D. (2011). On the creation of future probabilistic design weather years from UKCP09. Building Services Engineering Research and Technology, 32(2), 127–142. [Online] Available from: <http://dx.doi.org/10.1177/0143624410379934> [Accessed 17th July 2012] Edinburgh City Council (2010). 10/01630/FUL New semi-submerged gallery space (with environmental control) with external sculpture terrace above. Edinburgh College Of Art 13 Lady Lawson Street Edinburgh EH3 9DS. Edinburgh City Council, Scotland, UK. Eicker, U. (2010). Cooling strategies, summer comfort and energy performance of a rehabilitated passive standard office building. Applied Energy, 87(6), 2031–2039. Available from: <http://dx.doi.org/10.1016/j.apenergy.2009.11.015> [Accessed 6th June 2012] Fordham M. (2010a). Decoding sustainability. green offices matrix. The Architects’ Journal, 09.2010. Available from: <http://www.maxfordham. com/files/library/REFURB_offices_matrix_download.pdf> [Accessed 9th June 2012] Fordham M. (2010b). Decoding sustainability. refurbished offices matrix. The Architects’ Journal, 09.2010. Available from: < http://www. maxfordham.com/files/library/OFFICES_matrix_website_download.pdf> [Accessed 9th June 2012] Glasgow City Council (2007). 07-00575-DC External and internal refurbishment of office building. 141 West Nile Street, Glasgow. Glasgow City Council, Scotland, UK. Glasgow City Council (2009). 09-02526-DC Change of use from office tower to hotel. 141 West Nile Street, Glasgow. Glasgow City Council, Scotland, UK. Great Britain. Climate Change Act 2008: Elizabeth II. Chapter 27. (2008) London, The Stationery Office Jenkins, G. (2009). UK climate projections : briefing report. Exeter: Met Office Hadley Centre.


Hartless, R. (2004). ENPER-TEBUC project Final Report of Task B4 Energy Performance of Buildings: Application of Energy performance Regulations to Existing Buildings. Available from: <http://www.seattle.gov/environment/documents/enper_b4.pdf> [Accessed 9th June 2012] Kaufman, J. E., Christensen, J. F., and IES, (1987). IES lighting handbook: 1987 application volume. New York, N.Y.: Illuminating Engineering Society of North America. Knauf (2012). Systems solutions for drywall exteriors. Knauf AQUAPANEL® Exterior Wall. [Online brochure] Available from: <http://www. aquapanel.com/Content/Media/8e5e0ac2d2a24fc4a3e13dbbc57a419e/KEW_Commercial_brochure_HR-s.pdf> [Accessed 2nd July 2012] Laird, M. (1966). Castle Terrace Development, Edinburgh. [architectural documents]. Edinburgh. Edinburgh City Archives. Microsoft (2012a). Bing Maps - Argyle House, 3 Lady Lawson Street, Edinburgh EH3 9TH. Cartography by Navteq. [Online] Available from: <http://www.bing.com/maps/?v=2&cp=55.946694~-3.201239&lvl=19&dir=0&sty=h&form=LMLTCC> [Accessed 31st July 2012] Microsoft (2012b). Bing Maps - St Andrew’s House, 141 West Nile Street Glasgow G1 2RN. Cartography by Navteq. [Online] Available from: <http://www.bing.com/maps/?v=2&cp=55.864516~-4.253752&lvl=18&dir=0&sty=h&eo=0&where1=141%20W%20Nile%20Street%2C%20 Glasgow%20G2%203&form=LMLTCC> [Accessed 31st July 2012] Nicol, F., and Humphreys, M. A. (2009). New standards for comfort and energy use in buildings. Building Research & Information, 37(1), 68–73. [Online] Available from <http://dx.doi.org/10.1080/09613210802611041> [Accessed 25th July 2012] Nicol, F., Humphreys, M. A., and Roaf, S. (2012). Adaptive thermal comfort : principles and practice. London; New York: Routledge. Nicol, F., and McCartney, K. (2001). Final Report (Public) Smart Controls and Thermal Comfort (SCATs). Report to the European Commission of the Smart Controls and Thermal Comfort project. Oxford: Oxford Brookes University. Parnell, T. (2011a). Argyle House. [photograph] Available from: <http://www.flickr.com/photos/itmpa/5951228080/> [Accessed 17th July 2012] Parnell, T. (2011b). Argyle House. [photograph] Available from: <http://www.flickr.com/photos/itmpa/5951225092/> [Accessed 17th July 2012] Rennie, D., and Parand, F. (1998). Environmental design guide for naturally ventilated and daylit offices. Watford, Herts: Construction Research Communications. Rey, E. (2004). Office building retrofitting strategies: multicriteria approach of an architectural and technical issue. Energy and buildings, 36(4), 367–372. [Online] Available from < http://dx.doi.org/10.1016/j.enbuild.2004.01.015> [Accessed 6th June 2012] Rhoads, J. (2010). Better Buildings Partnership: Low Carbon Retrofit Toolkit. London: Better Buildings Partnership. Available from: <http://www. betterbuildingspartnership.co.uk/download/bbp_low_carbon_retrofit_toolkit.pdf> [Accessed 2nd August 2012]


Santamouris, M., and Hestnes, A. (2002). Office-passive retrofitting of office buildings to improve their energy performance and indoor working conditions. Building and Environment, 37(6), 555â&#x20AC;&#x201C;556. [Online] Available from: <http://dx.doi.org/10.1016/S0360-1323(02)00038-0> [Accessed 6th June 2012] Swift, A., and Partners (1961). Development at 36-68 Sauchiehall St., Glasgow. [architectural documents] Special Collections. Glasgow. Mitchell Library. Urquhart, J. (2010). St Andrews House Glasgow. [photograph] Available from: <http://www.flickr.com/photos/45060815@N07/4688116775/> [Accessed 13 July 2012] Urquhart, J. (2011). St Andrews House Glasgow. [photograph] Available from: <http://www.flickr.com/photos/45060815@N07/5352010047/> [Accessed 13 July 2012] van de Wetering, J., & Wyatt, P. (2010). Measuring the carbon footprint of existing office space. Journal of Property Research, 27(4), 309â&#x20AC;&#x201C;336. [Online] Available from: <doi:10.1080/09599916.2010.517851> [Accessed 6th June 2012] Vivian, P. (2012). Typological [r]evolution of the workplace. Artichoke, 2001 (37) [Online] Available from: <http://architecturenow.co.nz/articles/ typological-reevolution-of-the-workplace/> [Accessed 28th May 2012]


APPENDICES


APPENDIX A.

Input parameters for energy simulations with IES

Parameters for analysis Climate data Abbreviation Values

try test reference year

Parameters for analysis Climate data Abbreviation Values

try test reference year

B1.01 Season scenario w winter

External envelope values xuv walls 1.58 W/m²K

Floor/ceiling type fc

HVAC system chr central heating radiators

windows 5.23 W/m²K

false ceilings

External envelope values xuv

Floor/ceiling type fc

HVAC system nv

false ceilings

natural ventilation

Air tightness

Ventilation

ncm

min minimum ventilation (0,25ach)

NCM standard 10 m3/hm2 at 50Pa

Occupant density dod BCO default 11,6 m2/person

B1.02 Season scenario s summer

walls 1.58W/m²K windows 5.23W/m²K

Air tightness

Ventilation

ncm

dv

Occupant density dod

NCM standard 10 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

Existing constructions in the IES Apache database

APPENDICES

I


Parameters for analysis Climate data Abbreviation Values

try test reference year

Parameters for analysis Climate data Abbreviation Values

try test reference year

B1.03 Season scenario w winter

External envelope values nuv walls 0.28W/m²K

Floor/ceiling type fc

windows 1.98W/m²K

false ceilings

External envelope values nuv

Floor/ceiling type fc

HVAC system chr central heating radiators

Air tightness

Ventilation

ncm

min minimum ventilation (0,25ach)

NCM standard 10 m3/hm2 at 50Pa

Occupant density dod BCO default 11,6 m2/person

B1.04 Season scenario w winter

walls 0.28W/m²K windows 1.98W/m²K

false ceilings

HVAC system chr central heating radiators

Air tightness

Ventilation

iat green offices innovative 2 m3/hm2 at 50Pa

min minimum ventilation (0,25ach)

Occupant density dod BCO default 11,6 m2/person

New constructions in the IES Apache database

APPENDICES

II


Parameters for analysis Climate data Abbreviation Values

try test reference year

Parameters for analysis Climate data Abbreviation Values

try test reference year

B2.01 Season scenario w winter

External envelope values xuv walls 1.58 W/m²K

Floor/ceiling type fc

HVAC system chr central heating radiators

windows 5.23 W/m²K

false ceilings

External envelope values xuv

Floor/ceiling type fc

HVAC system nv

false ceilings

natural ventilation

Air tightness

Ventilation

ncm

min minimum ventilation (0,25ach)

NCM standard 10 m3/hm2 at 50Pa

Occupant density dod BCO default 11,6 m2/person

B2.01a Season scenario w winter

walls 1.58W/m²K windows 5.23W/m²K

Occupant density dod

Air tightness

Ventilation

mat minimum air tightness 25 m3/hm2 at 50Pa

min minimum ventilation (0,25ach)

Air tightness

Ventilation

ncm

dv

Occupant density dod

NCM standard 10 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

BCO default 11,6 m2/person

additionally light levels are increased by 30%

Parameters for analysis Climate data Abbreviation Values

APPENDICES

try test reference year

B2.02 Season scenario s summer

External envelope values xuv walls 1.58 W/m²K windows 5.23 W/m²K

Floor/ceiling type fc

HVAC system nv

false ceilings

natural ventilation

III


Parameters for analysis Climate data Abbreviation Values

E 2050 hi 90p - dsy 2050 high emissions scenario - 90th percentile

Parameters for analysis Climate data Abbreviation Values

E 2050 hi 90p - dsy 2050 high emissions scenario - 90th percentile

Parameters for analysis

Abbreviation

B2.03 Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

s

xuv

fc

nv

ncm

dv

dod

windows 5.23 W/m²K

false ceilings

natural ventilation

NCM standard 10 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

s

nuv

fc

nv

iat

dv

dod

windows 1.98W/m²K

false ceilings

natural ventilation

green offices innovative 2 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

summer

walls 1.58 W/m²K

B2.04

summer

walls 0.28W/m²K

B2.05

Climate data

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

fc

nv

iat

dv

oc8

Values

Parameters for analysis

Abbreviation Values

APPENDICES

8 m2/person

same as above

B2.06

Climate data

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

fc

nv

iat

dv

oc6

same as above

6 m2/person

IV


Parameters for analysis Climate data Abbreviation

try

Values

test reference year

Parameters for analysis Climate data Abbreviation Values

E 2050 hi 90p - dsy 2050 high emissions scenario - 90th percentile

Parameters for analysis Climate data Abbreviation Values

APPENDICES

E 2050 hi 90p - dsy 2050 high emissions scenario - 90th percentile

B2.07 Season scenario w

External envelope values xuv walls 1.58 W/m²K

Floor/ceiling type fc

HVAC Air tightness system uhp ncm underfloor heating with NCM standard air-source 10 m3/hm2 at 50Pa heat pump

Ventilation min

Occupant density dod

minimum ventilation (0,25ach)

BCO default 11,6 m2/person

windows 5.23 W/m²K

false ceilings

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

s

nuv

fc

nv

iat

dv

dod

windows 1.98W/m²K

false ceilings

natural ventilation

green offices innovative 2 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

s

nuv

xc

nv

iat

dv

dod

exposed concrete ceilings

natural ventilation

green offices innovative 2 m3/hm2 at 50Pa

daytime ventilation

BCO default 11,6 m2/person

winter

B2.08

summer

walls 0.28W/m²K

B2.09

summer

walls 0.28W/m²K windows 1.98W/m²K

V


Parameters for analysis

Abbreviation Values

Climate data

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

xci

nv

iat

dv

dod

exposed concrete ceilings with underfloor insulation

natural ventilation

2050 high walls 0.28W/m²K emissions summer scenario - 90th windows 1.98W/m²K percentile

Parameters for analysis

Abbreviation

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

xci

nv

iat

dv + niv

dod

daytime ventilation

same as above

same as above

B2.12

Climate data

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

xtci

nv

iat

dv

dod

daytime ventilation

same as above

exposed thicker ceilings with underfloor insulation

same as above

Parameters for analysis

APPENDICES

exposed ceilings with underfloor insulation

same as above

Values

Values

B2.11 Season scenario

Parameters for analysis

Abbreviation

BCO default green offices daytime 11,6 m2/ innovative ventilation 3 2 person 2 m /hm at50Pa

Climate data

Values

Abbreviation

B2.10

same as above

B2.13

Climate data

Season scenario

External envelope values

Floor/ceiling type

HVAC system

Air tightness

Ventilation

Occupant density

E 2050 hi 90p - dsy

s

nuv

xtci

nv

iat

dv + niv

dod

daytime and night time ventilation

same as above

same as above

exposed thicker ceilings with underfloor insulation

same as above

VI


APPENDIX B.

Max Fordham sustainability matrices

GREEN OFFICES SUSTAINABILITY MATRIX Sustainability Criteria

User and Operational Interaction

Building and Operational Targets

Proposed Building Regulations

Minimum Standard

Best Practice

Innovative

Pioneering

2010 Part L Regulation

2013 Part L Regulation

2016 Part L Regulation

2019 Part L - 'Zero Carbon'

Notes

'Zero Carbon' not yet fully defined Typical design stage modelled target

1 CO2 Emission design target

30 kg CO2/m /yr

21 kg CO2/m /yr

8 kg CO2/m /yr

0 kg CO2/m /yr “Carbon Neutral”

2 DEC rating

C rating

B rating

A rating

A+ rating

Target DEC used rather than EPC highly user dependent

Heating & hot water load

61 kWh/m2/yr

46 kWh/m2/yr

30 kWh/m2/yr

15 kWh/m2/yr

Electrical base load

16 kWh/m2/yr

15 kWh/m2/yr

13 kWh/m2/yr

12 kWh/m2/yr

Approximate values. Defined by A) The design Strategy; which is the base installed load and controls strategy defined by the design team, and B) The operation; which is under user control

IT and small power

48 kWh/m2/yr

41 kWh/m2/yr

33 kWh/m2/yr

26 kWh/m2/yr

Up to 20% based on local planning

>20% on site renewables

>50%

> 100% on site generation or agreed off-site generation

Wall

0.35 (Part L 2010)

0.2

0.15

0.1

Average window

2.2 (Part L 2010)

1.4

1.1

0.8

Roof

0.25 (Part L 2010)

0.15

0.12

0.1

Ground floor

2

2

2

2

3 Energy consumption

4 On site energy generation

Highly site specific.

5 U-values (W/m2K)

0.25 (Part L 2010)

0.15

0.12

0.1

6 Airtightness at 50 Pa

10 m 3/h.m 2 (Part L 2010)

3.5 m 3/h.m 2 (BCO guide)

2 m 3/h.m 2

1 m 3/h.m 2

7 Building occupancy

50-80% Desks occupied at any time of working hot desking/desk sharing for peripatetic staff. day. Cleaners/night-security aware of energy use

8 Controls, metering and monitoring

Seasonal Commissioning. Produce DEC, report to senior management

9 User involvement

Facilities Staff trained at building handover. Building Log Book provided with O&M Manual

Hot desking, remote working, 24hour use restricted to small areas.

Difficult to pass 2010 Building Regs using minimum regulation values: 20%30% improvement in U-values and airtightness typical.

Energy use and Carbon emissions could also be considered per person day worked.

Commissioning company retained to monitor over first year. Post occupancy evaluation. Action plan to respond to annual DEC

Responsibilities for reading, reviewing, actioning changes Continual monitoring, fine-tuning and feeding back. Formal external Evaluations show actual performance defined. Anonymised external reporting. Departmental energy review. Results published to industry. Energy use reward/penalty KPI's (eg in energy and water), are targets usually much greater than those system predicted during the design stage. Often a result of poor commissioning, Facilities staff involved in commissioning. Non-technical Soft landing framework followed (see note) Departmental energy use feeds into personal carbon trading (eg. training & management. user guide produced and all staff inducted. Energy use Interactive online user guide. Energy use on interactive display WSP's PACT scheme) www.softlandings.org.uk screen and online fed back to users

CIBSE / BCO design targets: Air conditioned Spaces: 24o C +/- 2oC Naturally ventilated: 25oC for <5% and 28oC for <1% working hours. External temperature to suit geographic location Natural ventilation where possible, otherwise mechanical ventilation and comfort cooling. VRV/VRF system used in Server room. Server room set point no less than 24oC

BCO Design Targets used, test the design to Building design tested to UKCIP 2080 Maximise adaptive comfort: UKCIP2020. internal temperature 2 oC < external temperature when external Dress code partly relaxed in warm weather as ISO7730 temperature> 27 oC, Dress code entirely relaxed. Eg allow shorts and short sleeves in summer. Building design tested to UKCIP 2050 Thermal mass in roof. Natural ventilation plus low Natural ventilation with comfort cooling served by GSHP or grade cooling or mixed-mode with heat recovery. mech vent with heat recovery. Free cooling and heat recovery Server room uses free cooling when possible to server room

12 Solar control

Provide fixed external shading. Manual Internal blinds

Orient and size windows for capturing useful daylight only. Provide some level of external shading with upgrade strategy to deal with future hotter summers Solar control glass, mid-pane blinds etc

13 Daylighting

Average 2% daylight factor where possible. Views to outside. Glare control blinds

Narrow plan floorplate or rooflights to provide daylight. Building form heavily influenced by daylight design. 80% floor At least 80% of the floor area has an average daylight factor of 5%. Views to sky. 80% floor area >2% average daylight and area >3% average daylight factor Reflection onto vertical surfaces to reduce perceived gloominess. uniformity 0.4 Building form led by daylight design

14 Artificial lighting and controls

300-500 lux to BCO and CIBSE guidelines. PIR 300 lux background lighting plus task lighting. Daylight detectors in WCs etc. Fluorescent fittings dimming and presence detection throughout building throughout

150-200 lux background & wall-washing plus task lighting. Daylight dimming & presence detection.

As innovative with new lighting technologies eg. LED's

Design to SLL Lighting Guide LG7

15 IT strategy

Users encouraged to switch off PCs overnight. Kill switch for non essential peripherals. Servers ramp down under part load. Consider laptops throughout

Thin client system – lower power terminals with centralised computing. Servers running virtualisation software

Off-site internet-based cloud-computing systems

cloud-computing = software and resources provided by Internet on demand, like the electricity grid

10 Summer thermal targets for energy reduction Design considerations and strategies

PAGE 1 OF 2: ENERGY CRITERIA

11 Thermal mass, ventilation and cooling

APPENDICES

Automatic adjustable external shading. Consider use of deciduous planting

Highly dependent on how staff use the building

Free cooling = directly coupled cooling

As innovative plus insulated shutters/blinds with reflective outer coating

Design to CIBSE Lighting Guide 10, BS8206 Part 2 and the BRE Site Layout Guide 10

VII


REFURBISHED OFFICE SUSTAINABILITY MATRIX Sustainability Criteria Proposed Building Regulations

Design considerations and strategies

User and operational interaction

Building and Operational Targets

1 CO2 emission target

PAGE 1 OF 2: ENERGY CRITERIA

Minimum Standard

Best Practice

Innovative

Pioneering

2010 Part L Regulation

2013 Part L Regulation

2016 Part L Regulation

2019 Part L - 'Zero Carbon'

Zero Carbon not yet fully defined

Green Office Best Practice or better

Potential for improvement depends largely on existing building

Notes

20%-40% improvement on existing

40-60% improvement or Part L2A 2006 Level

>60% Improvement or Part L2A 2010 Level

E-C

D-C

C-B

A

3 Proportion of capital spent on 'consequential improvements'

10% (2010 building regs Part L2B)

20%

30%

50%

Consequential improvements' = additional spending on improving energy usage

4 Energy Targets

Dependent on existing conditions. See Green office matrix for typical target levels

Dependent on existing conditions. See Green office matrix for typical target levels

Minimum Green Office matrix minimum standard

Minimum Green Office matrix minimum standard

Highly dependent on existing construction

5 On Site Energy Generation

0% on site renewables

10% on site renewables

25% on site renewables

>40% on site renewables

Indicative figures. Entirely site dependent.

6 U-values (W/m2K)

Upgrade thermal elements' U-values to achieve Where feasible replace windows with openable better L2B threshold values (Part L2B Table 5) thermally performing units. Improve thermal elements to at least Part L2A 2010 values

Replace and upgrade or replace thermal elements to 30% better than Part L2A 2010 values

7 Airtightness at 50 Pa

No pressure testing but improve airtightness where upgrading fabric

Consider use of thermal imaging. Target 10 m 3/hm 2

Target 5 m 3/hm 2

8 Building occupancy

50-80% of desks occupied at any time of the working day

Hot desking/desk sharing for peripatetic staff. Cleaners/night-security aware of energy use

Hot desking, remote working, 24 hour use restricted to small areas

9 Controls, metering and monitoring

Seasonal Commissioning. Produce DEC, report to senior management

Commissioning company retained to monitor over first year. Full post occupancy evaluation. Action plan to respond to annual DEC

Responsibilities for reading, reviewing, actioning changes defined. Departmental energy targets

10 User involvement

Facilities Staff trained at building handover. Building Log Book provided with O&M Manual

Facilities staff involved in commissioning. Non-technical Soft landing framework followed Departmental energy use feeds into personal carbon trading (eg. user guide produced and all staff inducted. Energy use Interactive online user guide. Energy use on interactive display WSP's PACT scheme) fed back to users screen and online

11 Summer thermal targets for energy reduction

Air conditioned spaces: <22 - 24 oC. External temperature to suit geographical location

BCO design targets. Dress code entirely relaxed. Eg allow Air conditioned spaces: <24oC. Naturally ventilated spaces: 25oC for <5% and 28oC for <1% working hours. shorts and short sleeves in summer. Building design tested Dress code partly relaxed in warm weather as ISO7730 against UKCIP 2050

Consider adaptive comfort: 2oC < external temp when external > 27OC. Building design tested against UKCIP 2080

Highly dependent on how staff use the building

12 Ventilation

Assess existing plant and re-use or upgrade if >15 yrs old and or financially viable

Consider alternative vent strategy, If natural ventilation, Retrofit thermal mass or phase change material if and where replace fixed windows with openable, up to 5% of active appropriate floor area. Expose thermally massive structures

Building form altered to improve ventilation eg, chimneys or atria added for stack-effect vent

Highly dependent on existing construction

13 Cooling Systems/Sources

Re-use existing. Retest, commission, add New more efficient chillers. Upgrade emitters or controls where necessary. Replace with more replace fan coils with modern EC high efficiency motor efficient emitters if >15 yrs old and or financially units viable

14 Solar control

Consider overheating and glare control. Review any use of solar film. Manual Internal blinds

Provide some level of external shading. Consider mid- External shading to S/E/W facades, limit direct sunlight. pane blinds, solar control glass Consideration of glazing % when re-cladding

Consider use of deciduous trees; sun tracking louvres; insulated window/rooflight blinds with reflective outer coating

15 Daylighting

Replace blinds to improve daylight. Consider repainting surfaces to improve reflectivity

Revise furniture layout to maximise daylight

re-configure floorplate to maximise daylight.

Improve window orientation as part of an improved faรงade. Consider Design to SLL Lighting Guide LG7 new rooflights or atrium creation

16 Artificial lighting and controls

Re-use existing lighting if it complies

New light fittings and controls. 300-500 lux on the working plane, PIR detectors in WCs etc. Low energy fittings throughout.

150-200 lux background plus task lighting. Luminance and presence on/off control throughout building.

Daylight compensating dimming on background lighting

Design in accordance with SLL Lighting Guide LG7

17 IT strategy

Energy use of IT system considered

Kill switch for non essential peripherals. Consider thin client system. Servers running virtualisation Servers ramp down under load, Heat reclaim on server software. Consider wireless office (reduced cabling) room

Use of off-site internet-based cloud computing systems

cloud-computing = software and resources provided by Internet on demand, like the electricity grid

2

APPENDICES

DEC rating improvement

Consider renewable cooling source such as GSHP combined with new emitters such as chilled beams.

Consideration of conservation constrictions due to planning Target 2 m 3/hm 2

Be aware of minimum ventilation rates for the building structure

Energy use and Carbon emissions could also be considered per person day worked. Continual monitoring, fine-tuning and feeding back. Results published to industry. Energy use reward/penalty system

Post occupancy evaluations of buildings have systematically shown that actual performance KPI's for example in energy and water consumption, are significantly greater than design predictions, often a result of poor commissioning, training & management. www.softlandings.org

Diurnal and seasonal storage used to full advantage. Active thermal mass

VIII


PAGE 2 OF 2 WIDER SUSTAINABILITY PARAMETERS

Productivity & Health

Management

Transport Issues

Waste

Water

Landscape & Biodiversity

Climate Change Adaptation

Construction Materials

Sustainability Criteria

Minimum Standard

Best Practice

Innovative

Pioneering

Notes Highly building specific and metrics not sufficiently standardised to allow benchmarks to be used as meaningful targets. Wise, June 2010, Building.co.uk, "What if everything we did is wrong" 2010, Sturgis Associates, "Redefining Zero"

1 Embodied carbon in fabric

Embodied carbon not assessed. Structure engineered to minimise material mass. Preference stated for locally sourced materials Cement replacements used, e.g. GGBFS in concrete heavy materials. Materials specified to be from local sources and provenance rigorously checked during construction

Detailed life cycle analysis of embodied carbon in structure including assessment sourcing and transportation energy. Results used for material selection. Structure engineered to work at 90% capacity [Wise]

Structure made from entirely low embodied energy materials, with known and mainly local provenance. Building serviceability regulations challenged [Wise]. Carbon Profiling technique utilised and used to inform building design and material selection [Sturgis]

2 Building and materials reuse

Preference for standard sizes of elements such Future flexibility of building considered. High grade as steel beams/columns or precast units. materials designed for recyclability. e.g. Using lime mortar. Different material layers made identifiable or visible. 15% recycled content likely as standard. 30% recycled content

Flexibility of future use demonstrated by typical conversion example designs. Avoid composite materials. Consider fastenings for easy dismantling.

Flexibility and future use drives design. Label & log or e-tag main elements.

45% recycled content

60% recycled content

Only applies to relevant materials

Use only natural materials where products exist. 80% of materials ‘A’ or ‘A+’ rated

Ratings refer to BRE Green Guide

3 Recycled and reclaimed Content 4 Material Toxicity

Avoidance of high VOC content paints, sealants PVC cabling exchanged for LSF. 'B' and 'C' grade materials avoided. VOC-free paints and etc and all ozone depleting materials including Non petro-chemical based insulation materials. All 'C' timber. Natural materials where possible. Eliminate PVC insulation rated materials avoided

5 Climate change adaptation

No considerations beyond those embodied in regulatory compliance

Potential impacts reviewed with client, Design is influenced by climate change adaptation implications Design approach driven by climate change adaptation implications strategic principles discussed and reported concerning key risks

See TSB report 'Design For Future Climate', 2010, & UKCIP for further guidance

6 Landscape and biodiversity

Local planning requirements met. Mitigate against negative biodiversity impacts where feasible

Consult an ecologist on biodiversity enhancement, giving preference to local species. Integrated landscape and water strategy with landscape management plan provided

Attach equal weighting to biodiversity as for water, M & E and Biodiversity enhancement key driver in Green Infrastructure Strategy. people, in overarching Green Infrastructure strategy. Landscape significantly influences building design. Landscape works in harmony with design and climate including deciduous planting to reduce summer urban heat island and internal solar gain where appropriate

Biodiversity is the variety of species within an ecosystem, used as a measure of the health of biological systems

7 Mains water consumption

> 5.5 m3/person/yr

4.5 m 3/p/yr

1.5 m 3/p/yr

<1.5 m 3/p/yr

8 Drainage systems

Carry out Flood Risk Assessment No increase in stormwater run-off.

Thorough site hydrological characterisation, design responds to environment, including SUDS where appropriate. Rainwater harvesting for WCs and irrigation.

Drainage system fully integrated into the environment. Consider reedbed treatment for irrigation.

Closed loop water system. Waste-to-Energy plant or alternatives to water base foul drainage

9 Construction waste minimisation

Contractor to produce Site Waste Management Establish waste streams during design, set key KPI's Plan (SWMP) to identify waste streams and early on. Waste reviews on design team meeting areas for segregation on site or post collection. agendas. Divert 75% by weight of non hazardous project waste from landfill.

Implement Modern Methods of Construction throughout Achieve zero net waste for project. design. Account for site conditions impacting waste. Materials logistics plan.

10 Operational waste recycling

Adequate space for storing recyclable waste.

Managed recycling processes involving space for separating and collecting recyclables. Encourage occupants to recycle.

Provide incentives for recycling. On site composting for biodegradable waste.

Waste stream feeds on or off-site anaerobic digestion for biogas production.

11 Transport

Some covered cycle storage.

Full cycling support provisions as part of travel plan. Utilise video conferencing. Access considered in site selection.

Fully site specific travel plan covering site infrastructure and awareness raising. Electric vehicle charging points. Utilise virtual video conferencing.

Accessibility drives site selection. Feed transport into personal carbon trading scheme.

12 Stakeholder involvement and design process

Use of industry Standards. Standard client briefing.

Early consultation with stakeholders with the declared intention that this may affect design proposals. Stakeholders fully understand standards and design

Open design process with published response to stakeholder proposals. Design strategy tested with stakeholders. New boundaries set

Feed back results into industry standards

13 Construction site management

Main contractor has CCS or alternative certification. Energy use in construction metered

Main contractor has 32 pts under CCS or an alternative Main contractor has CCS score 36 or more. Energy and water A significant proportion of construction energy is generated on site certification. Main contractor operates EMS including use targets are met and results published with temporary renewables. monitoring and setting targets for energy use

14 Sustainable procurement of consumables

Sourcing of office supplies and cleaning products considered

Sustainable procurement of office supplies and cleaning products and food and monitoring of consumption.

15 Healthy environments

Building has no or only a slight negative impact No impact on productivity. Connection to outside. Air on productivity. Meet regulation for internal quality monitored. comfort including air quality.

APPENDICES

Mostly paperless organisation. All consumables sustainably procured. Some food grown on site

Some organic food grown on site, with the rest seasonal, local.

Slightly positive impact on productivity. Psychological and social impacts assessed during design.

Building has noticeable positive impact on productivity. Strive to create a 'sense of place'.

Highly site specific

see WRAP for guidance on SWMP's and waste minimisation strategies

Adequate provision of storage lockers for change of clothes, helmet etc, can require a significant amount of internal space

Productivity a highly subjective measurement. See http://www.cibse.org/pdfs/8aratcliffe.pdf for further guidance

IX


APPENDIX C.

St Andrew’s House

Existing conditions. Typical floor plan _scale 1:200

APPENDICES

X


Retrofitted open plan. Typical floor plan _scale 1:200

APPENDICES

XI


APPENDICES

L3

L4

L5

L6

L7

L8

L9

L10

L11

L12

L13

L14

L15

L16

L17

ROOF

Cross section on the atrium with constant glazing ratio _ scale 1:200

XII


APPENDICES

L3

L4

L5

L6

L7

L8

L9

L10

L11

L12

L13

L14

L15

L16

L17

ROOF

Cross section on the atrium with progressive glazing ratio _ scale 1:200

XIII


Cross section _ Mitchell Library Archives _ out of scale

APPENDICES

XIV


A B C

APPENDIX D.

Argyle House

Typical floor plan _ scale 1:500

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

3

1

2

3

4

5

6

3

4

5

6

3

4

5

6

D

D

C

B

A

1

APPENDICES

2

3

4

5

6

3

4

5

6

3

4

5

6

XV

D


Floor plan _ floor D _ out of scale

APPENDICES

XVI


Floor plan _ floor E _ out of scale

APPENDICES

XVII


Floor plan _ floor F _ out of scale

APPENDICES

XVIII


Floor plan _ floor H _ out of scale

APPENDICES

XIX


Floor plan _ floor K _ out of scale

APPENDICES

XX


Cross section _ scale 1:400

APPENDICES

301.25 2030

ROOF

291.75 1740

L6

FLOOR M

282.25 1450

L5

FLOOR L

272.75 1160

L4

FLOOR K

263.25

870

L3

FLOOR J

253.75

580

L2

FLOOR H

244.25

290

L1

FLOOR F

234.75

00

L0

FLOOR E

225.25 -290

L-1 FLOOR D

215.75 -580

L-2 FLOOR C

206.25 -870

L-3 FLOOR B

XXI


Detail section of the classing system _ Edinburgh City Archives _ out of scale

APPENDICES

XXII


Sustainable Retrofitting of Office Buildings in the UK