Page 1

Issue 7 December 2017


Sustainable Design & Applied Research in Engineering and the Built Environment

The SDAR Journal is a scholarly journal in sustainable design and publishes peer reviewed applied research papers Cover SDAR Journal 2017.indd 1

07/01/2018 13:10

Breathing Life into Buildings a career that is exciting, makes a real

Building Services Engineers …

difference to people’s lives and safeguards

Have a passport to international work

Make a social and economic difference

Bring water to a village in Africa

Design a data centre for Google

Beam energy from solar space stations

Computer-simulate environmental events

Enhance people’s lives

Don’t settle for the ordinary – choose

the future of the planet … Become a Building Services Engineer. Architects design the body, civils build the skeleton but it is building services engineers who breathe life into buildings. They are the ones who provide the heart, lungs and veins of every building we work, play and live in! CIBSE 'Why Choose' Advert 2016.indd 1

07/01/2018 13:11

Contents 5 The Energy Performance of Buildings Directive – where are we going?

Hywel Davies, Technical Director, CIBSE,

11 The new Irish Building Regulations Part L: the impact on city centre developments Mona Holtkoetter, Arup

23 Energy Audit of a Fitness/Leisure Centre Paul Wynne, Callaghan Engineering Eoin McLean, Dublin Institute of Technology

35 A case study of the Omani electricity network and readiness for solar energy integration

Eugene Coyle, Dean of Military Technological College, Oman and Emeritus Professor, Dublin Institute of Technology, Ireland

Introduction Welcome to the seventh edition of the SDAR Journal which the Chartered Institution of Building Services Engineers (CIBSE Ireland) produces in partnership with the Dublin Institute of Technology (DIT). The publication of the SDAR Journal is used to promote sustainable design and applied research. This edition has again proved to be an excellent production with papers by three international authors and a further three by DIT graduates and academics. These are all peer-reviewed papers of the highest quality dealing with many aspects of the building services spectrum. To date the SDAR Journal has been downloaded over 22,000 times so If you are looking to stand out from the rest of your peers, and maybe to impress potential employers, then publishing a paper in this journal will take you a step above the rest. CIBSE Ireland represents circa 800 members from all areas of the building services sector. In co-publishing the SDAR Journal with DIT we have established a fantastic forum for research into all areas of the built environment. I wish to thank all of the researchers, authors, reviewers and editorial team on behalf of CIBSE Ireland for all of their great work. If you have an idea for a paper I would strongly encourage you to consider engaging with the SDAR team.

45 A reassessment of General Lighting Practice Based on the MRSE Concept Roderic Bunn Peter Raynham

57 An Examination of a new interior lighting design methodology using mean room surface exitance

Kevin Kelly, Dublin Institute of Technology, Ireland Antonello Durante, Dublin Institute of Technology, Ireland Editor: Dr Kevin Kelly, DIT and CIBSE Contact: Deputy Editor: Kevin Gaughan DIT Contact: Editorial Team: Kevin Gaughan, Yvonne Desmond, Keith Sutherland, Avril Behan, Michael McDonald, Paul Martin, Ciara Aherne, Brian Widdis, Pat Lehane, Kevin Kelly. Reviewing Panel: Dr Ivan Dudurych, Mr Joseph Little, Dr John McGrory, Dr Derek Kearney, Dr Avril Behan, Dr Keith Sunderland, Dr Martin Barrett, Mr Kevin Gaughan, Dr Marek Rebow and Dr Kevin Kelly. Upload papers and access articles online:

Paul Martin BEng Hons, CEng MCIBSE, CIBSE Ireland Chairperson

DIT is delighted to once again co-publish the seventh edition of this important journal. The ongoing collaboration between DIT and CIBSE Ireland represented by this publication is of great importance to us as an academic research community, and also represents very clearly DIT’s commitment to vital research and educational programmes in the area of building services engineering. DIT is undertaking two major projects at present with the development of our new campus at Grangegorman and an application for Technical University status by DIT and our partners ITT and ITB. A major foundation of the drive toward Technical University status is the quality and impact of applied research in DIT and its application in industry. As a college we place a strong emphasis on research in areas such as energy management, renewable energy technologies, electrical energy systems and sustainable design, all of which are vital to the future of Ireland, and indeed the future of mankind, given the very finite nature of our planet’s resources and the need to protect and nurture our environment. This journal offers authors from a variety of institutions and organisations an opportunity to share significant research contributions with the wider world of engineering and the built environment, and provides a direct high-quality means for this college to realise one of our core objectives. I congratulate the editors of the journal and all the authors on their strong contributions to research in this area, in Ireland and internationally.

Published by: CIBSE Ireland and the College of Engineering & Built Environment, DIT Produced by: Pressline Ltd, Carraig Court, George’s Avenue, Blackrock, Co Dublin. Tel: 01 - 288 5001/2/3. email: Printed by: Swift Print Solutions (SPS) ISSN 2009-549X © SDAR Research Journal. Additional copies can be purchased for F50

SDAR Intro pages 2017.indd 1

Professor Gerald Farrell Director and Dean of the College of Engineering and Built Environment, DIT

12/01/2018 16:52

SDAR Journal 2017


Editorial Board

As a country Ireland is not doing well in addressing the challenges

Professor Brian Norton Dublin Institute of Technology

posed by climate change. Indeed, ranked at 49th, it is the worstperforming European country in the Climate Change Performance Index CCPI ( ). It is likely that Ireland will miss its 2020 emission reduction targets and our performance with respect to greenhouse gas (GHG) emissions is nowhere close to being on track to meets its “well-below-2°C”compatible pathway. There are positive trends in the development of renewable energy, but Ireland still rates only medium in the renewables category. So what can the building services engineering community do? We are challenged to be innovative and creative with low-energy solutions. Reduced thermal demand, increased use of renewables and innovative lighting are at the heart of how we can address these challenges. The SDAR Journal provides a source of information and evidence about best practice with respect to energy reductions in the built environment and in the use of renewable energies. It is a peerreviewed, free and open-access journal ( that has had papers downloaded over 22,000 times from over 100 countries worldwide. The intention is to ensure that professionals in the engineering and built environment sector turn ideologically-green initiatives in to evidence-based sustainable solutions. The drive towards Near Zero Energy Buildings (NZEBs) requires careful evaluation of innovations to see if they work and, if not, then what has gone wrong. Apart from evaluating what we are doing, this also provides value to clients via evidence-based solutions with valid and reliable data. Clients need to understand that the cheapest solution is not often the best value but we, as a community, must present the evidence to convince them to increase their initial investment.

Professor Andy Ford London South Bank University Professor Tim Dwyer University College London Dr Hywel Davies CIBSE Paul Martin Chairman, CIBSE Ireland Professor Gerald Farrell Dublin Institute of Technology Professor John Mardaljevic Loughborough University Professor Michael Conlon Dublin Institute of Technology Professor David Kennedy Dublin Institute of Technology Professor Tony Day International Energy Research Centre – Cork Dr Kevin Kelly Dublin Institute of Technology, Vice-President CIBSE, Past-President SLL

The SDAR Journal editorial team encourages working professionals and young academic researchers to publish evidence-based findings with respect to best practice engineering and built environment design. It is by evaluating innovations that value is assured for clients and they can better see that sometimes a broader and longer-term view is required. To enquire about publishing a paper in the SDAR Journal contact Support will be provided in the editing and publishing process at no charge.

Dr Kevin T. Kelly C Eng FCIBSE FSLL Head of School of Multidisciplinary Technologies Dublin Institute of Technology Vice-President CIBSE Past-President SLL


SDAR Intro pages 2017.indd 2

15/01/2018 09:36

SDAR Journal 2016

A Reader’s Guide In the Energy Performance Directive paper, Dr Hywel Davies, who is Technical Director, CIBSE, updates readers about implementation of the EPBD Directive and considers how the latest recast will affect buildings in the UK and Ireland. However, and perhaps more importantly, it serves to assist us in addressing the energy challenges we face going forward in this respect. The next paper is a welcome contribution from a young female working engineer that complements the

first paper well. Mona Holtkoetter of Arup explores the potential impact of the Part L update as we move to Near Zero Energy Buildings (NZEB) for non-dwellings, and the requirement for a minimum renewable contribution. This paper applies simulation procedures to a Dublin City Centre office building and provides some insightful findings. The third paper is by another young working engineer. Paul Wynne

Roderic Bunn and Peter Raynham. Excessive lighting consumption, issues with Dali systems and the usability of controls are identified. Recommendations are provided on how to mitigate excessive lighting energy consumption and to

investigates the energy performance of a fitness/leisure centre in Dublin. Although only built in 2004 to a high standard and well maintained, energy savings with respect to CHP and lighting upgrades are identified and evaluated. The fourth paper is an international study from Oman. Professor Eugene Coyle initially describes the electricity network in Oman. The over reliance on fossil fuels may not be surprising but this reliance is expected to change significantly by harnessing high solar

improve the predictive power of the current energy assessment methods. The final paper by Kevin Kelly and Antonello Durante disseminates findings about a new lighting design methodology proposed by a New Zealand researcher. Multiple PhD research has been undertaken within DIT and this paper explains why change is needed, what is proposed, the benefits of the new methods and the implications for existing practice. It is shown that MRSE is a better measure of perceived adequacy of lighting, and proof of concept is provided that it can be easily designed and measured.

densities to reduce the country’s carbon footprint. Widescale domestic PV and concentrated solar power are examined. A wind farm is also considered.. The penultimate paper is from University College London and is a post-occupancy evaluation of two schools in the UK by 3

SDAR Intro pages 2017.indd 3

12/01/2018 16:48

Institiúd Teicneolaíochta Átha Cliath Dublin Institute of Technology Dublin School of Architecture College of Engineering & Built Environment Over the next three years the Nearly Zero Energy Buildings (NZEB) Standard will be applied to buildings built for, or rented by, public bodies; then to all new and retrofitted buildings. At the same time technological innovation and other environmental and building performance concerns are creating other needs and opportunities. Dublin School of Architecture has a range of postgraduate and post-apprenticeship programmes that meet these challenges. Practicing architects, technologists and engineers who wish to increase their knowledge and skills in delivering new build and retrofitted buildings to the impending NZEB Standard can join a range of multi-disciplinary, blended online CPD programmes. They may also wish to go further to become industry leaders and specialists in one or more areas of building performance. Applications are being accepted for September 2018. Code


NFQ level Duration



Postgraduate Certificate in Building 9 Performance (Energy Efficiency in Design)

1 year, part time



Postgraduate Diploma in Building 9 Performance (Energy Efficiency in Design)

2 years, part time



MSc in Building Performance 9 Performance (Energy Efficiency in Design)

3 years, part time



CPD Diploma in NZEB Design Tools


1 semester, part time F1,500


CPD Certificate in NZEB Policy and Technology


5 weeks, part time


CPD Diploma in NZEB Thermal Bridge


2 semesters, part time F1,500


Contact: Site foreman and supervisors working for general builders and subcontractors who wish to engage better with the way information is increasingly delivered or created on site using digital and mobile technologies should attend CPD IT for Site Workers in DIT Bolton Street. Applications are being accepted for January and September 2018. Code


ARCH6001 CPD IT for Site Workers

NFQ level Duration 6

13 weeks part time

Fee F1,050


For further details see:

DIT School of Architecture advert 2016.indd 1

08/11/2016 14:50

Enhancing Thermal Mass Performance of Concrete

The Energy Performance of Buildings Directive – where are we going?

Dr Hywel Davies


Hywel Davies 2017.indd 1

07/01/2018 13:15

SDAR Journal 2017



The EU adopted the Energy Performance of Buildings

The Energy Performance of Buildings Directive[1], or EPBD, came into force on 4 January 2003, and was implemented across Europe between 2006 and 2008. It introduced the concept of an energy certificate for a building, required when a building is constructed, sold or rented out. It also introduced energy certificates for many public buildings, which should be displayed in an accessible location. And it introduced regular inspections of heating and air conditioning systems.

Directive in 2003 to help to measure, manage and reduce energy consumption and consequential carbon emissions related to buildings. It introduced the concept of energy certificates for buildings on construction, sale or rent. It required energy certificates for display in many public buildings across Europe and introduced regular inspections of heating and air conditioning systems. The Directive was recast in 2010, to include a number of amendments aimed at improving the effectiveness of the legislation. The Directive is now being reviewed again and the European Commission, the Parliament and the Council of Ministers are now engaged in a three-way process of negotiation to finalise the text. This paper looks at the history of the implementation of the EPBD and considers how the recast might affect buildings

The Directive was recast in 2010, with various amendments which were implemented between 2011 and 2013. There were a number of changes to the detailed requirements of the EPBD, all aimed at improving the effectiveness of the legislation. The EPBD is now being reviewed again, with the European Commission and Parliament and the Council of Ministers now engaged in a three way process of negotiation to finalise the text of “EPBD 3”. This paper looks at the implementation of the EPBD to date and considers how the recast might affect buildings in both Ireland and the UK. It also seeks a wider perspective on how the EPBD can help to tackle the energy challenges we face in each jurisdiction.

in both Ireland and the UK. It also seeks to offer a wider perspective on how the Directive may be able to help address the energy challenges we face in both Ireland and the UK.

Keywords EPBD, energy performance, emissions reduction, refurbishment, minimum energy standards. Glossary Building Energy Rating – BER Committee on Industry, Research and Energy – ITRE Electric Vehicles – EV Energy Efficiency Directive – EED Energy Performance of Buildings Directive – EPBD Energy Performance Certificates – EPCs Information and Communication Technologies – ICT Member States – MS National Energy Efficiency Action Plan – NEEAP Nearly Zero Energy Buildings – nZEBy

Background The EPBD is almost 20 years old in concept. In 2000 the EU adopted an energy efficiency action plan, which led to a call for specific measures to address the energy efficiency of European buildings. It was then estimated that the EU had 160 million buildings which were responsible for over 40% of Europe’s energy consumption and associated carbon dioxide emissions, a proportion that was then increasing. Current EU figures suggest that buildings still consume 40% of energy and are responsible for 36% of carbon emissions Fuel for space heating accounted for half of overall building energy use, with water heating accounting for a further third of which 25% was in domestic and 9% in non-residential buildings. The European Commission estimated a saving potential of around 22% of consumption in buildings in 2000 could be realised by 2010, on which basis the original EPBD was adopted The primary aims of the EPBD were to raise awareness of energy use in buildings, encourage the building sector towards more ambitious energy efficiency standards, and increase the use of renewable energy sources. A key requirement was for member states to review their energy performance standards for buildings and report the findings to the commission at least every five years. It also set out to require member states within the EU to take steps to make energy use in buildings more transparent and widely understood. Energy Certificates have played a prominent role in informing potential purchasers and tenants about the energy performance of building units, such as an apartment or office space, or of entire buildings. They allow comparisons of buildings or building units in terms of their energy efficiency. In theory they should influence the demand for buildings with better energy performance and using


Hywel Davies 2017.indd 2

07/01/2018 13:15

The Energy Performance of Buildings Directive – where are we going?

a high proportion of energy from renewable sources. This was expected to increase their market value and provide a market driver to stimulate building owners to renovate their buildings. In both the UK and Ireland the EPBD changed the way that energy use in buildings is regulated, both for new buildings and refurbishments. While Northern Ireland and the Republic of Ireland, and indeed England, Wales and Scotland, all have their own building regulations and standards, each was significantly changed in response to the adoption of the EPBD. In particular, the introduction of energy certificates for construction, sale or rental of a building set in train the creation of a new industry dedicated to the provision of energy certificates and the training, certification and management of energy assessors, particularly in the domestic sector. The Directive was recast in 2010 with strengthened targets for the adoption of low-carbon technology and the introduction of the concept of nearly zero energy buildings (nZEB), which the Directive requires to be adopted by member states throughout the EU by 2021 for all buildings, and 2019 for the public sector. The recast also required national plans for nearly zero energy buildings. Article 2 set out the full requirements, as follows: (1) The common general framework for a methodology for calculating the integrated energy performance of buildings and building units; (2) The application of minimum requirements to the energy performance of new buildings and new building units; (3) The application of minimum requirements to the energy performance of: – existing buildings, building units and building elements that are subject to major renovation;

Ireland was ahead of both, with its first National Energy Efficiency Action Plan published in 2009, and updated in June 2011 in response to the EPBD recast, and again in 2014. The full set of documents is available online[5] on the website of the Department of Communications, Climate Action and Environment. The Plan sets a clear vision for each sector it covers to enable both public and private sectors to mobilise. The Plan has been reviewed and updated and certain actions from the first version replaced as appropriate to endeavour to stay on target to meet national and EU targets. The recast also placed a greater emphasis on enforcement. Article 27 of the recast required that “penalties provided for infringements against national provisions must be effective, proportionate and dissuasive.” There has been some controversy in England and Wales about whether this Article has been implemented in a meaningful way in practice. What has the EPBD achieved? There have been several achievements in energy policy in the EU, to which the EPBD has no doubt contributed in some part. Decoupling of energy demand and economic growth Energy demand and economic growth have been effectively decoupled in the EU, a point which is also made by the UK government in its recent Clean Growth Strategy. Whereas previously energy efficiency progress kept energy demand stable despite economic growth, the European Commission argues that Europe’s economy can now grow while also achieving energy savings in absolute terms, as shown in Figure 1. Between 2000 and 2014 the ratio of aggregate primary energy use to GDP fell by around 20%.

– building elements that form part of the building envelope and that have a significant impact on the energy performance of the building envelope when they are retrofitted or replaced; and – technical building systems whenever they are installed, replaced or upgraded; (4) National plans for increasing the number of nearly zero-energy buildings; (5) Energy certification of buildings or building units; (6) Regular inspection of heating and air-conditioning systems in buildings; and (7) Independent control systems for energy performance certificates and inspection reports. The UK National Energy Efficiency Action Plan (NEEAP) was issued in July 2011[2], updating a previous document issued in 2007. Scotland published “Conserve and Save: Energy Efficiency Action Plan (EEAP)”[3], in October 2010, setting out Scottish Government policies and options on energy efficiency. Publication and periodic updating of NEEAPs is an obligation under EU Directive 2006/32/EC on energy end-use efficiency and energy services which has since been superseded by EU Directive 2012/27/EU on energy efficiency [4]. The latter directive also includes a requirement for all member states to establish long-term strategies for energy efficient renovation of buildings.

Figure 1. Evolution of energy consumption and GDP in the EU 2005- 2014 (Source: Eurostat).

Even in the recent financial crisis energy savings from improved energy efficiency appear to have outweighed reduced demand caused by the downturn. If this is not the case, then the challenges we face in meeting the future targets set out in national plans, in the EU energy strategy and by the Paris Agreement are even greater. However, energy efficiency actions can stimulate economic growth and counter the adverse effects of an economic downturn. Some EU member states’ (MS) energy efficiency action programmes actively seek to harness this macroeconomic benefit. While consumption trends vary significantly across member states, this is largely due to supply and demand structures in the energy


Hywel Davies 2017.indd 3

07/01/2018 13:15

SDAR Journal 2017

system and reflects successful experiences from early adoption of energy efficiency measures in certain sectors and member states. This suggests that analysis and exchange of good practice is essential to deliver further energy savings by 2030, in line with EU targets and indeed in line with UK targets set out in response to the UK Climate Change Act. One excellent but possibly little-known example of this is the EU Concerted Action for the EPBD, which started at the time of the first Directive and has continued to this day, bringing together experts and officials to share experiences and best practice examples. The Concerted Action has produced valuable information on the implementation of the EPBD [5]. Improved standards of building energy efficiency The EPBD required member states to adopt a national minimum energy efficiency standard for new buildings. This was to be based on a set of specific properties described in an Annex to the EPBD, and member states were encouraged to adopt European Standards, but each member state was responsible for setting their own minimum. The EPBD did require each member state to undertake a “cost optimal review”, effectively a life-cycle analysis of their minimum standard, using a Commission-prescribed methodology every five years, and report the results, and then to review the national minimum standard against that review. As a result a variety of standards apply across the EU. In many countries this triggered interest in the private sector and, in some member states in social housing, to go beyond the minimum standards or seek to undertake energy-saving refurbishment of the existing building stock, an example being the KfW building programmes in Germany [7]. The evaluation of the recast EPBD in 2016 shows clear progress in improving the efficiency of the building sector as the decrease in energy consumption per unit floor area accelerated markedly after 2006 when the original EPBD came into force. This was further reinforced by the effect of the recast EPBD in 2013 and 2014. There is evidence of around 37 million tonnes of oil equivalent (Mtoe) in additional final energy savings in 2013 compared to the 2007 baseline of the recast EPBD. This is taken by the EU to indicate that the Directive is likely to deliver the expected impacts by 2020. However, recent coverage in Ireland [8] has suggested that Irish emissions may currently be rising. Reduced energy demand in heating, hot water and lighting It is hard to define just what the EPBD has achieved and what is due to minimum energy efficiency standards for energy-using products, such as heating and lighting appliances, as illustrated in the Figure 2. This shows that over half the savings in energy are due to improvements in lighting, space heating and water heating products, which together account for 55% of the savings. It is essential to note that Figure 2 combines actual savings to 2016 with projected savings to 2050. Its purpose is to show the savings attributed to products as a consequence of the Ecodesign policy, which works alongside the EPBD and EEED.

Figure 2. Primary energy saving of products in Ecodesign impact accounting Source: “Ecodesign Impact Accounting – Status January 2016” Van Holsteijn en Kemna B.V. (VHK) for the European Commission.

These savings have been realised because of the specific requirements of the Ecodesign framework for these product families, and not as a result of the EPBD. However, more efficient products were a requirement to meet some of the more challenging aspects of energy certification, and the EPBD will have helped to drive the uptake of more efficient heating, hot water and lighting systems. While it is also arguable that the savings in lighting energy would have been realised without legislation as LEDs came into the market, the speed of adoption has been driven by the Ecodesign framework and the drive to improve standards under the EPBD. It is also clear that without regulatory action on lighting sources there would have been a significant body of late or non-adopters of energy efficient-lighting, motivated in part by a dislike of change but also driven by the poor experience of some of the early energy-efficient light sources, which had performance and durablity problems over time. The “Clean Energy Package” On 30 November 2016, the European Commission adopted a “Clean energy for all Europeans” package. It consists of eight legislative proposals and other actions to help the EU meet its 2030 energy and climate goals. These include a targeted revision of the 2010 Directive on the energy performance of buildings. The Commission proposal retains the main features of the existing EPBD and modernises and streamlines other requirements. It introduces binding obligations on electro-mobility requirements in buildings, introduces a ‘“smartness indicator”, and sets clearer requirements for national databases on energy performance certificates. What changes could the proposed revision bring? The Commission proposes a targeted revision of the EPBD, retaining the overall objectives while making limited changes to improve the way the Directive functions. This retains the main features of the current EPBD but modernises and streamlines some specific requirements. There are mandatory obligations on electro-mobility requirements in buildings and a new “smartness indicator”, intended to indicate the technological capability or readiness of buildings for energy self-production and consumption and measurement. There are also clearer requirements for national databases on energy


Hywel Davies 2017.indd 4

07/01/2018 13:15

The Energy Performance of Buildings Directive – where are we going?

performance certificates. Ireland has already been identified as exemplary, along with Portugal, in following the Danish model in the way that it operates the national register of energy certificates and for its BER software. Although the UK opted to create a national database when implementing the EPBD, it was considered that it went beyond the strict requirements of the original Directive. If the EPBD had come into force after 2010 it is hard to imagine that a database would have been established.

efficiency investments and using public funding to leverage privatesector investment.

While the overall evaluation of the EPBD[9] was positive, there are areas which could be further strengthened. Energy performance certification schemes and their independent control could be enhanced in several member states. There is also a widespread feeling that in many member states more could be done to enforce the national provisions which implement the current Directive before making any further changes. While Ireland has a good BER system, there is a view that it is not so well applied or enforced in practice, a view which is widely held about the energy certification regime in the UK.

The revisions would introduce an obligation to document the overall energy performance after any technical building systems are installed, replaced or upgraded. This would be available for verification of compliance, passed on to the building owner, and included in national databases of energy performance certificates (EPCs), where such databases exist. EPCs should be regularly updated to track actual energy consumption data of any buildings covered. They would be obliged to cover all public buildings with a useable floor area over 250m². Aggregated and anonymised data would be made available for statistics and research.

In the public consultation on the EPBD undertaken for DG Energy in 2015, many stakeholders were critical of the uneven implementation across member states. Three hundred and eight (308) stakeholders replied from all EU member states: 58% were organisations such as business associations and professional bodies; 20 % individual companies; and the remainder were public authorities, individuals or other groups. Stakeholders generally consider that the EPBD sets a good framework to improve energy performance in buildings and raise awareness of energy consumption. A third of respondents feel the EPBD has not been successful and fewer than half think it has been successful.

The proposal streamlines and simplifies existing EPBD provisions on inspections of heating and air conditioning systems. The revised EPBD would seek to enhance the use of building automation, and to ensure continuous performance and monitoring of energy efficiency, thereby limiting the necessity and frequency of physical inspections.

Several respondents felt it was too early to assess the achievements of the EPBD due to delayed implementation in member states, including: slow uptake, poor compliance and enforcement of measures, and low rates of building renovation. Most respondents consider that compliance is inadequate and could be improved through stronger procedures and sanctions. Energy performance certificates have only had a very limited impact on the rate and depth of renovation. Other issues raised included an insufficient take-up of available financing (partly due to its complexity), insufficient awareness of benefits due to a lack of information and advertising, split incentives between landlords and tenants, lack of consumer demand (linked to absence of long-term goals on renovation), and a lack of trust about the financial benefits. The Commission proposal therefore introduces targeted amendments to the EPBD while maintaining many provisions and implementation deadlines, for instance the requirement for all new buildings to be “nearly zero energy buildings” (nZEB) from 2021 onwards (from 2019 for the public sector). The proposal incorporates existing provisions on long-term renovation strategies (which are currently part of the EED) into the revised EPBD. These strategies should now introduce specific milestones for 2030, aim to deliver the long-term goal of a decarbonised building stock by 2050, specify measures to alleviate energy poverty, and guide investment decisions by aggregating projects, de-risking energy

The proposal requires member states to satisfy the general obligation that all new buildings meet minimum energy performance requirements. However, it is acknowledged that the mandatory regular inspection regime, which was first devised over 15 years ago, needs to be updated to take account of developments in continuous digital monitoring of building performance.

The proposal promotes e-mobility through a new requirement for recharging points for electric vehicles in the parking spaces of new buildings. Non-residential buildings under construction or undergoing major renovation and with more than 10 parking spaces would have to provide a charging point for electric vehicles for one parking space in every 10 and install cables for all spaces. This would apply to all non-residential buildings with more than 10 parking spaces, including existing buildings, from 2025. However, EU energy ministers have agreed to propose a complete exemption from charging requirements for geographical areas with specific vulnerabilities and to reduce the requirements for non-residential buildings so that only one electric vehicle charging point is required in any non-residential building, and only one in three parking spaces would need to have cabling installed. The proposal introduces a “smartness indicator” that assesses the technical capacity of the building to interact with its occupants and with the grid. The “smartness indicator” will be further defined by the Commission through a specific “delegated act” (quite possibly a Directive). The Ministers in the Energy Council have now proposed that the “smartness indicator” be a voluntary scheme whose key features (general framework) are outlined in the annex. The legislative proposal was accompanied by a ”Smart finance for smart buildings initiative“, which seeks to focus the use of existing EU funds, primarily regional development and cohesion funds, European Investment Bank loans and the European Fund for Strategic Investments, to improve energy performance in buildings, to increase use of renewables in self-generation and self-consumption, and to facilitate demand response through the adoption of advanced ICT. The major goal of this is to improve the investment climate for energy efficiency and provide greater confidence for investors


Hywel Davies 2017.indd 5

07/01/2018 13:15

SDAR Journal 2017

in energy efficiency-related activities. This may involve deploying financial instruments and flexible energy efficiency and renewable financing platforms to make more effective use of public funds. If adopted it will also require further assistance and aggregation to support the project pipeline at both an EU and local level, along with enhanced project development facilities, including a “One-stopshop” to provide greater support for energy efficiency schemes. It is also proposed to provide information and a platform for de-risking investments in energy efficiency, and to help investors and financiers to understand the risks and benefits of such investments. A 2016 study on boosting building renovation in Europe was carried out for the Committee on Industry, Research and Energy (ITRE) of European Parliament. It found that the current rate of building renovation is low, with 1-2 % of the building stock renovated each year. It considered that “the vast majority of these renovations do not use the full potential energy savings that could be achieved”. The study considers various policy options which have informed the committee in its scrutiny of the European Commission proposal. The ITRE Committee reviewed the Commission proposals in considerable depth. In response to the draft ITRE report produced in April, there were 570 amendments tabled and 53 compromise amendments were subsequently proposed. The final report was adopted in October, allowing inter-institutional negotiations between the Parliament, Council and Commission to start. The ITRE report seeks further requirements relating to the long-term renovation strategies, linking them explicitly to EU energy efficiency goals for 2030 and 2050, and introducing obligations for public consultation. The charging point requirements are reduced in line with the Council proposal. That said, on most other aspects the ITRE report is more demanding on member states than the Commission proposal. New buildings should have self-regulating devices to control room temperature in each room; more residential buildings would require inspections for air-conditioning, ventilation and heating systems; and building automation and control systems would become a requirement by 2023 in all non-residential buildings with an annual energy consumption of over 250MWh. The ITRE report proposes that the Commission assesses the potential to harmonise national energy performance certificates and conducts a feasibility study on the introduction of building renovation passports. The ITRE proposes keeping the “smartness indicator” as an obligatory measure and to outline its key features and a general framework in the annex.

Conclusions While this is an EU Directive, it is likely to come into force before the UK leaves the EU, and so it is likely to be included in the provisions of the UK’s EU Withdrawal Bill. Existing requirements of the EPBD, such as nearly Zero Energy Buildings, are already written into UK legislation. Given the recent confirmation of the Government’s commitment to the UK Climate Change Act, which is set out in the Clean Growth Strategy, it is inconceivable that these existing enactments of the requirements of the current EPBD will not be retained. In Ireland

the new version of the Directive will be adopted and should help to guide the development of new buildings and the refurbishment of the existing stock for the next decade or more. It is clear that on issues of energy, emissions and buildings the UK and the EU are co-travellers on a journey to a decarbonised low-emissions future, and that is not dependent on the ongoing negotiations over Brexit. In this area of policy we have a degree of clarity about what needs doing. CIBSE members have the knowledge and skills to deliver the proposed measures, and also understand that energy is not the only consideration in delivering safe, comfortable, healthy buildings which are well ventilated. This is one area where engineering knowledge and expertise transcends borders and where CIBSE members can combine to make tomorrow’s buildings better than today’s. References [1]

Directive 2002/91/EC of the European Parliament and Council, on the energy performance of buildings. TXT/?uri=CELEX%3A32002L0091 (accessed 8th December 2017).


UK Report on Articles 4 and 14 of the EU End-use Efficiency and Energy Services Directive (ESD). Update on progress against the 2007 UK National Energy Efficiency Action Plan, July 2011, available from (accessed 8th December 2017).


“Conserve and Save: Energy Efficiency Action Plan (EEAP)”, October 2010, available from 07142301/0 (accessed 8th December 2017).


Directive 2006/32/EC TXT/?uri=celex%3A32006L0032 on energy end use efficiency and energy services which has since been superseded by EU Directive 2012/27/EU on energy efficiency (accessed 8th December 2017).

[5] (accessed 8th December 2017).

[6] (accessed 8th December 2017).


As of 1 January 2012, the German Development Bank KfW has introduced two programs, the KfW Energy Efficiency Programme and KfWEnvironment Programme. The programmes provide loans for the financing of environment protection and energy saving investments for private companies and self-employed persons. Activities can be financed as long as they have positive impact on the environment.http://iepd.iipnetwork. org/policy/kfw-environmental-and-energy-efficiency-programmes-formallyerp (accessed 8th December 2017)

[8] (accessed 8th December 2017).


Commission staff working document – evaluation of Directive 2010/31/EU on the energy performance of buildings, accompanying the document Proposal for a Directive of the European Parliament and of the Council amending Directive 2010/31/EU on the energy performance of buildings CELEX:52016SC0408 (accessed 8th December 2017).


Hywel Davies 2017.indd 6

07/01/2018 13:15

Enhancing Thermal Mass Performance of Concrete

The new Irish Building Regulations Part L: the impact on city centre developments

Mona Holtkรถtter


Mona Holtkoetter 2017.indd 1

07/01/2018 14:42

SDAR Journal 2017


1. Introduction

An update of the Building Regulations Technical Guidance

The Department of Housing, Planning, Community and Local Government has released a draft new Building Regulations Part L – Buildings other than dwellings [1]. The draft document was out for public consultation until 2 June 2017 and is expected to come into force by the end of 2018 [2]. The draft Building Regulation reflects requirements introduced by the Energy Performance of Buildings Directive (EPBD) at EU level. Article 2(2) of Directive 2010/31/EU introduces the requirements of nearly zero energy buildings (NZEB), which are defined as “…a building that has a very high energy performance, as determined in accordance with Annex I. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced onsite or nearby” [3].

Document Part L has been announced by the Department of Housing for the end of 2017. This update introduces the requirements for Nearly Zero Energy Buildings (NZEB) for buildings other than dwellings and embraces a minimum renewable energy contribution. This paper is based on the draft Part L 2017 and explores the potential impact the update has on current building design strategies, using a Dublin city centre office building as an example. The paper outlines the simulation procedures using a currentlyavailable software program and compares the building design strategies for compliance with Part L 2008 to the requirements for compliance with draft Part L 2017.

Keywords Part L 2017, Nearly Zero Energy Buildings, NZEB, Renewable Energies, Energy and Carbon Performance.

In addition to the draft Part L release, the Department of Housing, Planning, Community and Local Government has published an “Interim NZEB Performance Specification for new buildings owned and occupied by Public Authorities.” This document applies to new buildings that are owned and occupied by public authorities and should have been used in the design of all new buildings from 1 January 2017 [4]. The Part L 2017 regulations apply to works that take place on or after 1 January 2019. A transitional agreement is noted in the Draft Part L that allows the use of Part L 2008 for projects where planning approval is applied for on or before 31 December 2018 and substantial work is completed by 1 January 2020 [1]. In addition to the Draft Part L Regulations, the Sustainable Energy Authority Ireland (SEAI) has issued an Interim NZEB Performance Specification Calculation Methodology and Excel tool used for the analysis in this report [5],[6]. This technical report takes a critical look at the impacts of the new regulations, using an existing building as an example. The example project and building name is not mentioned due to confidentiality. The building is located in Dublin city centre and will be owned and occupied by a public authority. Planning permission for this building was granted in 2016 under the Building Regulations TGD Part L – Buildings Other than Dwellings, 2008. As construction has not commenced, it is most likely that the building will fall under the new NZEB requirements. The report gives an overview of the new Part L/NZEB requirements and analyses the design changes needed to meet the new regulations. These changes include the new Energy Performance Coefficient (EPC) and Carbon Performance Coefficient (CPC), as well as the Renewable Energy Ratio (RER). For the RER, each compliant renewable option will be analysed and assessed for its practicality. Based on the example building, the report will review the impact of the new Part L/NZEB regulations on the current design process and design strategies, and will outline the challenges project teams will face to comply with the new requirements.


Mona Holtkoetter 2017.indd 2

07/01/2018 14:42

The new Irish Building Regulations Part L: the impact on city centre developments

2. Overview of the Interim NZEB Performance Specification The NZEB specification strives to improve building energy performance by 50% to 60% compared to current requirements [2]. In addition to this, a minimum renewable energy target of 10% has been set. The improvements are explained in more detail in the next paragraph. 2.1 Simulation procedure The energy performance of a building is analysed through the Nondomestic Energy Assessment Procedure (NEAP) using the iSBEM software provided by the SEAI. NEAP is used to assess the Part L requirements by comparing the energy consumption of an actual building to a reference building.

Changes between Part L 2008 and the new Part L/NZEB regulations are reflected by the increased performance of the reference building. The overall efficiency of the reference building increased by circa 50% to 60%.

3. Benchmark Office Building The sample project used for this analysis is a 16,000m2 office building, located in Dublin city centre. The building was designed to meet the Part L – 2008 regulations, achieving an EPC of 0.36 and a CPC of 0.36 under the 2008 Part L simulation. The efficiencies used were mainly driven by the requirement to achieve a Building Energy Rating of A3, which was part of the client brief. Less efficient systems could have been used to achieve Part L – 2008 compliance.

The Part L/NZEB requirements will be simulated using the existing iSBEM v3.5b software and an RER calculation tool issued by the SEAI in Q1 2017. As outlined in the NZEB Performance Specification, to simulate the Part L/ NZEB requirements with the existing iSEBM software, the user has to follow the steps outlined below: 1. Manually create a reference building using Interim Public Sector Specification; 2. Simulate the performance of the actual building using the actual specification; 3. Compare the primary energy use and carbon dioxide emissions of the reference and the actual building. These will result in an Energy Performance Coefficient (EPC) and a Carbon Performance Coefficient (CPC). ܲ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚ ܲ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ோ௘௙௘௥௘௡௖௘஻௨௜௟ௗ௜௡௚

[i] [1]

‫ܱܥ‬ଶ ‫ݏ݊݋݅ݏݏ݅݉݉ܧ‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚ ‫ ܥܲܥ‬ൌ ‫ܱܥ‬ଶ ‫ݏ݊݋݅ݏݏ݅݉݉ܧ‬ோ௘௙௘௥௘௡௖௘஻௨௜௟ௗ௜௡௚

[ii] [2]

‫ ܥܲܧ‬ൌ

To comply with the NZEB specification an EPC of 1.0 and a CPC of 1.15 need to be achieved. 4. Use the Excel tool provided by the SEAI to define the renewable energy contribution. This will depend on the EPC and CPC achieved:

Figure 1 – Building simulation model image.

3.1 Building Fabric Table 1: Building Fabric Values Construction Element

Part L 2008 reference values Appendix C

Design U-Values (to meet BER A3 rating)


0.27 W/m2K

0.20 W/m2K

Glazing (Glass and Frame)

2.2 W/m2K

1.20 W/m2K


0.22 W/m2K

0.16 W/m2K

Ground/ Exposed Floor

0.25 W/m2K

0.20 W/m2K



EPC 1.0 & CPC 1.15 Æ RER 20% EPC 0.9 & CPC 1.04 Æ RER 10% The performance of the reference building is defined in Appendix C of the Draft Part L Regulations as well as Appendix 1 of the Draft Interim Public Sector NZEB Performance Specification. Compared to the current 2008 Part L regulations, the performance of the reference building has improved, including: • Improved building fabric performance; • Increase mechanical equipment efficiencies; • Increase lighting efficiencies and added occupancy and daylight control.

An air permeability of 3 m3/m2/h @50Pa was assigned to the model. Thermal bridging values as per Part L 2008 Table D2 were applied to the model[7]. 3.2 Mechanical System Efficiencies The current specification for the building is fully air conditioned, using a 4-pipe fan coil unit system. Gas-fired boilers will produce heating while water-cooled chillers, in conjunction with hybrid dry coolers, will provide cooling. The systems were set up with the following efficiencies:


Mona Holtkoetter 2017.indd 3

07/01/2018 14:42

SDAR Journal 2017

Gas-fired boiler, 92% efficiency;

Water cooled chiller, SEER 6.49 and EER 5.0;

Specific fan power 1.5 W/l/s;


AHU heat recovery 73% (thermal wheel);

Optimal heating system controls

Dedicated hot water boiler 90% efficiency;

Hot water secondary circulation losses <10 W/m, 0.15kW pump power.

Table 3: Primary Energy and Carbon Emission Factors

These system efficiencies are based on the design for Part L 2008 compliance and do not take NZEB requirements into account.

Carbon Emission Factor

Natural Gas






ܲ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚ ൌ ሺͳ͹Ǥ͸͸ ൅ ͶǤʹ͸ሻ ή ͳǤͳ ൅ ሺͺǤͷͳ ൅ ͳͻǤͺͳ ൅ ʹͳǤͳ͵ሻ ή ʹǤͳͻ [i] ൌ ͳ͵ʹǤͶͳܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ܲ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ோ௘௙௘௥௘௡௖௘஻௨௜௟ௗ௜௡௚ ൌ ൫ሺʹͷǤ͵ͳ ൅ ͶǤʹʹሻ ή ͳǤͳ ൅ ሺʹͲǤͲʹ ൅ ͳͳǤͷͳ ൅ ͶͷǤͶͻሻ ή ʹǤͳͻ൯ െ ͶͲǤʹͶ ൌ ͳ͸ͲǤͻʹܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

3.3 Lighting The lighting was set to 8W/m2 at 500 lux. Occupancy sensing was allowed for the whole building and daylight control was added to the perimeter zones.

Primary Energy Factor

With the primary energy uses, the EPC can be calculated using the formula [i]. The CPC is calculated with formula [ii].

4. Changes required to meet new EPC and CPC The NZEB simulation was set-up as described in section 2.1. The iSBEM software program simulates the energy use for each end-use as illustrated in Table 2 and multiplies these with the relevant primary energy and carbon emission factor to calculate the annual primary energy use and the carbon emission. Table 2: Actual and Reference Building Energy Uses results iSBEM Energy Use


‫ ܥܲܧ‬ൌ

ͳ͵ʹǤͶͳܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ൌ ͲǤͺʹ ͳ͸ͲǤͻʹܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

‫ ܥܲܥ‬ൌ

͵͵Ǥ͹͸݇݃‫ܱܥ‬ଶ Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ൌ ͲǤͺ͵ ͵͵Ǥ͹Ͷ݇݃‫ܱܥ‬ଶ Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

The EPC limit for compliance with the new Part L/NZEB regulations is 1.0 and the CPC limit is 1.15. The office building therefore meets the new EPC and CPC requirements without changing the initial design strategy developed to meet Building Regulations Part L 2008, and achieves a Building Energy Rating of A3. This design strategy represents current design standard for Dublin office buildings.

5. Changes required to meet RER

Actual Building [kWh/m2/year] (Reflecting building design)

Reference Building [kWh/m2/year] (Reflecting NZEB minimum requirements)

Heating Energy



Cooling Energy



Auxiliary Energy



The initial design for compliance with Part L 2008 and achieving a BER A3 rating did not include any renewable energies. Under the new Part L/NZEB requirements, the building needs to meet a renewable energy ratio (RER) of 10%, as the EPC <0.9 and the CPC <1.04. Results based on a 20% RER requirement have been included for information. This section of the report analyses the opportunities for each renewable energy system allowed by the SEAI and reviews the practicability of introducing these renewable energies to the building for 10% and 20% RER.

Lighting Energy



The compliant renewable technologies are as follows:

Hot Water Energy




Solar panel – thermal;

Wind energy;


Biogas CHP;

Biomass boiler;

Heat pumps.

The primary energy and carbon emission factors are illustrated in Table 3. These factors are set by the SEAI. The primary energy consumption for the reference building is calculated by multiplying the energy consumption of the reference building by the applicable primary energy factor, adding the results. Twenty per cent (20%) of the energy consumption of the reference building will be provided by renewable energies and will therefore be subtracted. The primary energy consumption for the actual building is calculated by multiplying the energy consumption of the designed building by the applicable primary energy factor, adding the results.

5.1 Photovoltaic (PV) 5.1.1 Requirements to meet RER To calculate the RER when using PV, the following formula is applicable.


Mona Holtkoetter 2017.indd 4

07/01/2018 14:42

The new Irish Building Regulations Part L: the impact on city centre developments

ܴ‫ ܴܧ‬ൌ


ܲ‫݁ܿݎݑ݋ݏ݈ܾ݁ܽݓ݁݊݁ݎ݉݋ݎ݂ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ ܶ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܲܽݐ݋‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚


To find out the amount of primary energy that needs to be provided by PV, the total primary energy consumption can by multiplied by the RER.

Table 4: PV PV Array Type

ܲ‫ ܸܲݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ ʹͲΨ ή ܶ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܲܽݐ݋‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚ [iv]

PV Area PV Efficiency Primary RER Meets Meets Efficiency Energy RER 20% RER 10% [m2] ? ? [kWh/ m2 / year]

ܲ‫ ܸܲݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ ʹͲΨ ή ͳ͵ʹǤͶʹܹ݄݇Ȁ݉ଶ Ȁ‫ = ݎܽ݁ݕ‬26.48 ܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

Monochristalline 3,200 Silicone






For the 10% renewable energy option, the primary energy is calculated as follows:

Monochristalline 1,600 Silicone






Polychristalline Silicone







Amorphous Silicone







Other thin films 4,000






ܲ‫ ܸܲݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ ͳͲΨ ή ܶ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܲܽݐ݋‬஺௖௧௨௔௟஻௨௜௟ௗ௜௡௚ [v] ܲ‫ ܸܲݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ ͳͲΨ ή ͳ͵ʹǤͶʹܹ݄݇Ȁ݉ଶ Ȁ‫ = ݎܽ݁ݕ‬13.24 ܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

Dividing the primary energy from PV through the primary energy factor for electricity will show the energy that needs to be provided by the PV system. ‫ ܸܲ݉݋ݎ݂ݕ݃ݎ݁݊ܧ‬ൌ

ܲ‫ݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ ܲ‫ݕݐ݅ܿ݅ݎݐ݈ܿ݁ܧݎ݋ݐܿܽܨݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬


‫ܸܲ݉݋ݎ݂ݕ݃ݎ݁݊ܧ‬ሺ‫Ͳʹ݁݀݅ݒ݋ݎ݌݋ݐ‬Ψܴ‫ܴܧ‬ሻ ൌ ൌ ͳʹǤͲͻܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

‫ܸܲ݉݋ݎ݂ݕ݃ݎ݁݊ܧ‬ሺ‫Ͳͳ݁݀݅ݒ݋ݎ݌݋ݐ‬Ψܴ‫ܴܧ‬ሻ ൌ ൌ ͸ǤͲͷܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬

ʹ͸ǤͶͺܹ݄݇Ȁ݉ Ȁ‫ݎܽ݁ݕ‬ ʹǤͳͻ

ͳ͵ǤʹͶܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ʹǤͳͻ

This calculation shows the amount of energy that needs to be generated by on-site PV to achieve the RER. The renewable energy contribution from PV has to be simulated using the iSBEM software. In the software program, it is possible to input area of PV, the PV type and orientation of the panels. The input is limited to four panels with a maximum of 1,000m2 each. Three PV types can be selected – Monochristalline Silicone, Polychristalline Silicone and Amorphous Silicone. The simulation assumes a different efficiency factor for each of these PV types as shown in Table 4[8]. The simulation was set-up with the PV area orientating south at a 30° angle with all three PV types available. The simulation results are shown in Table 4. The results shown in Table 4 illustrate that 3,200m2 of south-facing Monocrystalline or 4,000m2 Polychristalline PV at a 30° angle is required to meet an RER of 20%. A RER of 10% can be achieved with 1,600m2 of PV. 5.1.2 Feasibility The office block is a 10-storey, high-rise building with a total roof area of 1,908m2. The public realm area around the building is not feasible for PV as this area is shaded by adjacent high-rise buildings. A feasible area of 1,600m2 PV could be placed on the roof. This would take most of the roof area and would not leave any space for rooftop terraces or a green roof. This area would provide 10% of the RER. There is the possibility to reduce the overall energy consumption of the building to reduce the requirements on PV. The overall energy consumption of the building would need to be reduced to 1/3 of the current consumption to make a PV solution feasible.

The simulation was run changing the building from an air conditioned office building to natural ventilation, to analyse the effect on RER requirements when cooling energy is excluded. With the change, the actual building energy consumption dropped from 132.42 kWh/m2/ year to 98.38 kWh/m2/year using formula (iv) and (v) to calculate the primary energy contribution required by PV. ܲ‫ ܸܲݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ ͳͲΨ ή ͻͺǤ͵ͺܹ݄݇Ȁ݉ଶ Ȁ‫ = ݎܽ݁ݕ‬9.8 ܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ‫ ܸܲ݉݋ݎ݂ݕ݃ݎ݁݊ܧ‬ൌ

ͳͻǤ͸ͺܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ൌ ͶǤͷܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ʹǤͳͻ

For a naturally-ventilated building, 25% less PV area will be required to meet the renewable energy ratio. Using the most efficient Monochristalline Silicone type of PV, 1,280m2 of south-facing PV would be needed. This area could be accommodated with the roof area available, but would cover a large extent of the roof area.

5. Solar Panel – Thermal 5.2.1 Requirements to meet the RER The simulation software limits the area of solar thermal panels to 400m2. This area delivers 12.98 MJ/m2. The primary energy from solar panels is calculated by the fuel that would otherwise be used by the hot water generator and takes the heating efficiency and primary energy factor of this system into account. Gas fired hot water generation, originally selected for the building with 91% efficiency, was used with a primary energy factor of 1.1. ܲ‫ ݎ݈ܽ݋ܵݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ

‫݈݁݊ܽܲݎ݈ܽ݋ܵݕܾݕ݃ݎ݁݊ܧ‬ [7] ή ܲ‫݉݅ݎ‬Ǥ ‫݈ܿ݁ܧݎ݋ݐܿܽܨݕ݃ݎ݁݊ܧ‬Ǥ [vii] ‫ݕ݂݂ܿ݊݁݅ܿ݅ܧݎ݈݁݅݋ܤ‬

ܲ‫ ݏ݈݁݊ܽܲݎ݈ܽ݋ܵݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ൌ

ͳʹǤͻͺ‫ܬܯ‬Ȁ݉ଶ ή ʹǤͳͻ ൌ ͺǤ͸ͺܹ݄݇Ȁ݉ଶ Ȁ‫ݎܽ݁ݕ‬ ͵Ǥ͸ ή ͲǤͻͳ

5.2.2 Feasibility A RER of 20% or 10% cannot be met with solar panels for this project. Only 5% RER is achieved. Solar panels are not a feasible option to meet the RER as a stand-alone solution.


Mona Holtkoetter 2017.indd 5

07/01/2018 14:42

SDAR Journal 2017

5.3 Wind Energy

ܴܲ‫ܧ‬஼ு௉ ൌ ܳ‫ݏܽܩ‬஼ு௉ ή  ‫ ்ܧ‬ή ൬

5.3.1 Requirements to meet RER The same amount of energy as calculated under 5.1.1 needs to be generated by wind energy to cover the RER. The wind turbine needs to generate 12.09 kWh/m2/year to meet the RER. Based on the building size, this is a total of 193,440kWh per year. Based on manufacturers’ information, a free-standing, large-scale, wind turbine with 22m rotor diameter can produce 209,153 kWh per year at an average wind speed of 6m/s[9]. The NEAP procedure does not allow manufacturers’ data to be used. The wind turbine output needs to be simulated using iSBEM. This should ensure conformance between projects. The simulation program was used to simulate a large-scale wind turbine, using the manufacturer. The turbine is set up with the following parameters: •

Terrain type is urban with average building height >15m. (This applies a terrain factor of 0.24 which reduces the power calculated by the software accordingly. In addition, a roughness length of 1 is used to calculate a roughness coefficient depending on the hub height. For the urban terrain type, the factor is 1);

Hub height 30m;

Rated power 60kW;

Horizontal Axis 22m.

The simulation results show an annual energy production of 2.32 kWh/m2/year from the wind turbine. This covers 4% of the annual energy consumption and does not achieve the 10% or 20% RER. The simulation shows that the stated output by the manufacturer is different to the simulation results. This is due to the manufacturer’s data being referred to measurements in an unobstructed area, whereas the simulation takes the urban area into account. A small-scale roof-mounted wind turbine was not simulated as the requirements cannot be met using a large-scale wind turbine.

ܲ‫ீܨܧ‬௔௦ ܲ‫ܨܧ‬ா௟௘௖ ܲ‫ீܨܧ‬௔௦ ൅ ‫ ܲܪܥ݂݂ܧ݈ܿ݁ܧ‬ή  െ ൰ ‫ܧ‬஻ ‫்ܧ‬ ‫்ܧ‬

ܴ݁݊݁‫ ܲܪܥݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܾܲ݁ܽݓ‬ൌ ͵ͳǤͻ͵

ܹ݄݇ ͳǤͳ ʹǤͳͻ ͳǤͳ ܹ݄݇ ή ൬ ൅ ͵ʹΨ ή  െ ൰ ൌ ͳͲǤͻͶ ݉ʹ ͲǤͺ͸ ͷͺΨ ͷͺΨ ݉ʹ

ܴܲ‫ܧ‬஼ு௉ ൌ ܴ݁݊݁‫ܲܪܥݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܾܲ݁ܽݓ‬ ܳ‫ݏܽܩ‬஼ு௉ ൌ ‫ܲܪܥ݊݋݅ݐ݌݉ݑݏ݊݋ܥݏܽܩ‬ ‫ ்ܧ‬ൌ ݄ܶ݁‫ܲܪܥݕ݂݂ܿ݊݁݅ܿ݅ܧ݈ܽ݉ݎ‬ ܲ‫ீܨܧ‬௔௦ ൌ ܲ‫ݏܽܩݎ݋ݐܿܽܨݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ ܲ‫ܨܧ‬ா௟௘௖ ൌ ܲ‫ݕݐ݅ܿ݅ݎݐ݈ܿ݁ܧݎ݋ݐܿܽܨݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ‬ ‫ܧ‬஻ ൌ ‫ݕ݂݂ܿ݊݁݅ܿ݅ܧݎ݈݁݅݋ܤ݉ݑ݉݅݊݅ܯ‬

Based on the efficiencies used, the renewable primary energy provided is 10.94 kWh/m2/year which leads to an 8% RER. 5.4.1 Feasibility CHP requires predictable and constant loads for optimal performance and will be more cost-efficient when operating continuously. Fluctuating thermal loads will either require a reduction in the power generation by the CHP or the rejection of waste heat which reduces the overall CHP efficiency [10]. For an office block the hot water generation would provide a constant load throughout the year. Heating will not be required during summer. The hot water load alone is small compared to the overall energy consumption and only achieves a RER of 1%. Even a full load CHP only provides 8% of the RER and is not a feasible option for this project. 5.5 Biogas CHP Compared to the CHP calculation in Section 5.4, the primary energy provided by the biogas CHP is higher, as the fuel used for the CHP is considered renewable. The primary energy factor is calculated as follows: ܴ݁݊݁‫ܲܪܥݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܾܲ݁ܽݓ‬ ൌ ‫݃݊݅ݐܽ݁ܪ‬ ܲ‫ݏܽܩܨܧ‬ ܲ‫݈ܿ݁ܧܨܧ‬ ή൬ ൅ ‫ ܲܪܥ݂݂ܧ݈ܿ݁ܧ‬ή  ൰ ‫݂݂ܧݎ݈݁݅݋ܤ‬ ݄ܶ݁‫ܲܪܥ݂݂ܧ݈ܽ݉ݎ‬

5.3.2 Feasibility Due to the city centre location, a large-scale wind turbine cannot be practically incorporated into the project. A roof-mounted wind turbine would be more applicable to this project, but would only provide a fraction of the energy that a large-scale turbine would provide. The performance of roof-mounted wind turbines in urban locations is reduced compared to a free-standing turbine, as buildings obstruct air flows and create turbulence. In addition, wind turbines mounted on buildings create structural vibration and noise implications. 5.4 CHP The CHP was set-up using a sample selection to provide the full heating and hot water load to the project. A thermal seasonal efficiency of 58% and a heat to power ratio of 1.8 was used. Based on this data, the simulation results show a CHP usage for heating and hot water of 31.93 kWh/m2/year. The renewable primary energy supplied by the CHP is based on the heating and hot water provided by the CHP, multiplied by the ratios of the primary energy factors and the electrical and thermal efficiencies.


ܴ݁݊݁‫ ܲܪܥݕ݃ݎ݁݊ܧݕݎܽ݉݅ݎ݈ܾܲ݁ܽݓ‬ൌ ͳͺǤͷʹ ൌ Ͷ͸ǤͲ͸

ܹ݄݇  ݉ʹ

[ix] [9]

ܹ݄݇ ͳǤͳ ʹǤͳͻ ή ൬ ൅ ͵ʹΨ ή  ൰ ݉ʹ ͲǤͺ͸ ͷͺΨ

The primary renewable energy provided by the biogas CHP provides an RER of 38% and exceeds the requirements by the NZEB regulations. 5.5.1 Feasibility Biogas is not a feasible energy source for a city centre project. Requirements around the biogas storage cannot be reasonably incorporated into the planning scheme. In addition, biogas is not readily available in Ireland. Biogas is therefore not a feasible option for this building, even though the percentage of RER can be met. Biogas could become a more feasible option if the market adapts and can guarantee a piped biogas supply for city centre locations. 5.6 Biomass Boiler The primary energy used by a biomass boiler is determined by multiplying the heating and hot water energy consumption by a primary energy factor of 1.1. The total primary energy consumption


Mona Holtkoetter 2017.indd 6

07/01/2018 14:42

The new Irish Building Regulations Part L: the impact on city centre developments

for biomass is 24.13 kWh/m2/year. Comparing this to the overall primary energy consumption of the building using formula 3, only 18% RER can be achieved.

The following formula is used to calculate the primary energy provided by the heat pump for heating and hot water:


ܴ‫ ܴܧ‬ൌ

ଶସǤଵଶ మ ೘ ೤೐ೌೝ

= 0.18

ೖೈ೓ ଵଷଶǤସଶ మ ೘ ೤೐ೌೝ

Similar to Section 5.2, a change to a naturally-ventilated building was analysed for the biomass boiler. For a naturally-ventilated building the cooling element was completely removed from the simulation. This change resulted in a reduction in total actual building energy usage and an increased proportion of heating load compared to the overall load. Using Formula 3, the biomass boiler option achieves 44% RER. ೖೈ೓

ܴ‫ ܴܧ‬ൌ

ସଶǤ଼ଷ మ ೘ ೤೐ೌೝ ೖೈ೓

The heat pump efficiency for heating and hot water needs to be above 219% to be counted as renewable energy. This is a minimum requirement set by the SEAI.

൬͵ͷͲΨ ή

ͳǤͳ ͳǤͳ െ ʹͳͻΨ൰ ‫ כ‬ͶǤͷʹ ൅ ൬͵ͷͲΨ ή െ ʹͳͻΨ൰ ‫ͳ כ‬Ǥͳ͵ ͲǤͺ͸ ͲǤͺ͸ ܹ݄݇ ൌ ͳʹǤͻͳ ଶ  ݉ ‫ݎܽ݁ݕ‬

The heat pump renewable primary energy of 12.91 kWh/m2/ year provides a renewable energy ratio of 9% which does not meet the RER. 5.7.1 Feasibility

= 0.44

ଽ଼Ǥଷ଻ మ ೘ ೤೐ೌೝ

5.6.1 Feasibility Providing renewable energy with biomass does meet the 10% RER, but falls short if 20% would be the target. Biomass is a renewable energy system purely based on the energy for heating and hot water. This load only accounts for 18% of the total building energy consumption when the building is air conditioned. A renewable energy solution for heating and hot water only will only achieve the RER as a single system if the RER target is 10%. For a 20% target, an additional 2% would need to be met by an alternative type of renewable energy, e.g. PV. An area of 510m of PV would be required to deliver 1.1 kWh/m / year to provide the additional 2%. 2


Frequent deliveries and large storage areas required for biomass can often be a problem, particularly in the context of this city centre site. The RER can be met when the building air conditioning system is removed and the building will be fully naturally ventilated. 5.7 Heat Pumps The system was changed in the iSBEM simulation to heat pump, using the efficiencies outlined in Table 5. Different types of heat pumps can be used, such as air to water heat pumps, ground source heat pumps or VRF systems. These efficiencies used are based on a VRF system selection by Mitsubishi Electric. The energy use of the actual building (listed in Table 2) changes due to the change in system type. The actual building total primary energy consumption changes to 139.81 kWh/m2/year.

A heat pump system would be feasible to install for a city centre office building, as there are no fuel delivery, storage or space challenges. A heat pump system on its own reaches 9% of the RER and would be just below meeting the RER target of 10%. To achieve the 10% or 20% RER target, this could be achieved in combination with a PV installation as outlined in Section 5.1. 5.8 Renewable Energy Results Table 6 summarises the renewable energy options and the RER percentages achieved by each option for an air conditioned building. Table 6: Renewable Energy Results Renewable Energy Solution

RER Air Conditioned Building

NZEB compliant for 20% RER?

NZEB compliant for 10% RER?

PV (full roof)




Solar Thermal




Wind Energy




CHP (domestic hot water)




CHP ((heating and domestic hot water)




Biogas CHP


Yes (not feasible)

Yes (not feasible)





Heat Pump




In the Excel tool the percentage of heating and hot water, and the efficiencies, need to be entered. These were set to 100% for both heating and hot water. The values shown in Table 5 were used: Table 5: Heat Pump Heating

Hot Water

Percentage Supplied



Heat Pump Efficiency



Figure 2 Renewable Energy Results.


Mona Holtkoetter 2017.indd 7

07/01/2018 14:42

SDAR Journal 2017

To meet the 10% RER there are several options that can be considered – biomass or a heat pump in combination with PV. None of the renewable energy solutions can meet the RER of 20% individually with the exception of biogas CHP. As discussed in Section 5.5, this would not be a feasible option for a city centre project. Therefore, a combination between a heating-based renewable energy system such as biomass, or a heat pump and a PV system (electricity based), would be required. Table 7: Combination of Renewable Energy Solutions Combination of Renewable Energy Solutions


NZEB 20% complaint?


510m2 PV


Heat Pump

1,500m PV



6. Limitations This section discusses the limitations of the new Part L/NZEB regulations and the iSBEM simulation tool. 6.1 Limitations of iSEBM 6.1.1 Simplicity The initial purpose of the simulation tool was to provide a comparison tool between all buildings in Ireland for Building Energy Rating and compliance check with Part L. The tool was not intended for design purposes. With the new Part L/NZEB regulations, the simulation tool enhances the renewable energy contribution and with that drives design decisions and project investments. There would be an argument to introduce dynamic simulation instead of iSBEM to provide a more accurate prediction of the energy uses, and therefore a more accurate renewable energy contribution. Detailed simulation procedures and guidelines would need to be provided by the SEAI to make dynamic simulation feasible. 6.1.2

Project Typology

The tool purely focuses on heating, hot water, auxiliary, lighting and cooling and does not take any process energy into account. Considering renewable energy for example for a healthcare project or a production facility, the process loads would be a major driver for selecting renewable energy systems. This is not accounted for in the NZEB simulation. 6.2 Limitations of the NZEB Methodology The renewable requirements of the new Part L/ NZEB methodology does not place any emphasis on the actual feasibility of the systems for different project types, nor the actual operation of the system. The introduction of a CHP in an office building for example, does not consider if any of the heat provided by the CHP will be used in the building. The tool leads to oversized CHPs whereas the usage would not be constant and heat would need to be dumped during periods. CHPs could be integrated to buildings for a “tickbox” exercise to

meet NZEB regulations but would not lead to an energy-efficient solution [11]. A second example is PV. The simulation requires an area of PV but does not take overshadowing into account. PV arrays in shaded areas could be installed to meet the regulations, but this would not provide an efficient solution for the building.

7. Impact of new Part L/ NZEB regulations on current design process The new Part L regulations will significantly impact the current design process in terms of capital costs, space and planning considerations. The analysis shows that the initial design methodology used for this office building does not meet the new regulations and changes need to be introduced. Particular emphasis will be placed on the integration of renewable energy, finding the optimal solution between renewable energy systems to find the cost optimum solution for the client. This will influence the system selection typically used in offices in Dublin which is gas-fired boilers in combination with a chiller and FCUs. The renewable energy options that were shown to be feasible to meet the new Part L/NZEB regulations are heating-based solutions (heat pump or biomass boiler) when a 10% RER is required. If a 20% RER is needed, these solutions would only be feasible in combination with PV (heat pump and PV or biomass boiler and PV). Purely electricallybased solutions such as PV or wind energy are not feasible on their own. Purely heating and hot water based solutions are only feasible for the 10% RER target, as the heating and hot water load showed to be less than 20% of the overall energy consumption for the sample project analysed. The building design will be pushed to provide a more energy-efficient building solution to target the 10% RER and reduce the amount and size of renewable energies. This will influence architectural and building envelope design. More emphasis will be based on a holistic design approach between all design teams to find the cost-optimum solution for the client. It is envisaged that project teams will need to provide detailed cost analysis between renewable energy systems and building envelope improvements to arrive at the most feasible and cost-optimum solution for the client. An alternative way of compliance is the shift from air conditioned buildings to naturally-ventilated buildings. This is currently not a market option for a high-profile Dublin office building but could be a low-budget solution to meet the new Part L/ NZEB regulations. A market shift to naturally-ventilated buildings could be caused by the new regulations.

8. Conclusions The report reviewed the new Part L regulations that are introducing a requirement for Nearly Zero Energy Buildings (NZEB), and the effect on a city centre office building design. NZEB introduces an increased requirement for building envelope and system efficiencies


Mona Holtkoetter 2017.indd 8

07/01/2018 14:42

The new Irish Building Regulations Part L: the impact on city centre developments

and presents a minimum renewable energy contribution. The report highlights that the increased requirements for building envelope performance and system efficiencies can be met with a building designed to meet a Building Energy Rating of A3, which represents current design standard for Dublin office buildings. On the other hand, the renewable energy contribution for an air conditioned office building depends on the overall building efficiency. Buildings that just meet the new Part L energy efficiency requirements need to provide 20% renewable energy. This can only be achieved using a combination of a heating/domestic hot water based solution, as well as an electricity-based renewable energy system. The most feasible options are a biomass boiler in combination with PV, or a heat pump system in combination with a large area of PV. For projects that exceed the new overall energy and carbon requirements, a 10% renewable energy contribution applies. Technically feasible solutions are biomass, heat pumps or PV. It is expected that more emphasis will be placed on a holistic design approach between the design teams to reduce the overall energy consumption to reduce the amount of renewable energy required. Cost analyses will be needed to review the cost-optimum solution. The regulations could also cause a market shift from air conditioned to naturally-ventilated buildings, as this reduces the amount of renewable energy needed. This would provide a low-cost option for compliance, but suitability of natural ventilation and the impacts on design aspects such as internal temperatures, façade design and thermal comfort could provide complications that need to be assessed on a project by project base.

References [1]

Department of Housing, Planning, Community and Local Government, Draft Building Regulations 2017 Technical Guidance Document, Buildings Other than Dwellings, ISBN 978-1-4064-2594-69


Passive House + Sustainable Building, Dept of Housing Set to launch new Part L for non-domestic buildings, 11 January 2017, dept-of-housing-set-to-launch-new-part-l-for-non-domestic-buildings (access 14 March 2017)


European Parliament and the Council of the European Union, Directive 2010/31/EU on the energy performance of buildings, 19 May 2010


Department of Housing, Planning, Community and Local Government, Interim NZEB Performance Specification for new buildings owned and occupied by Public Authorities, 22 December 2016, http://www.qualibuild. ie/wp-content/uploads/2017/07/Interim-NZEB-Public-buildings.pdf (Access 14 March 2017)


Sustainable Energy Authority of Ireland, Interim NZEB Performance Specification Calculation Methodology, Q1 2017, Your_Building/BER/Non_Domestic_buildings/NZEB-Commercial-and-PublicSector/Nearly-Zero-Energy-Buildings.html (Access 17 April 2017)


Sustainable Energy Authority of Ireland, Interim NZEB Specification Tool Version 1, Q1 2017, Domestic_buildings/NZEB-Commercial-and-Public-Sector/Nearly-ZeroEnergy-Buildings.html (Access 17 April 2017)


Minister of the Environment, Heritage and Local Government, Building Regulations 2008 Technical Guidance Document, Buildings Other than Dwellings, 2008


Sustainable Energy Authority of Ireland, Non-domestic Energy Assessment Procedure (NEAP) Modelling Guide & SBEM Technical Manual version 3.5.a, 3 December 2010


Aeolos Wind Turbine, Aeolos-H 60kW Secification, http://www. (Access 22 March 2017)

[10] The Chartered Institution of Building Services Engineers, Application Manual AM 12 Combined Heat and Power for Buildings (CHP), January 2013 [11] Irish Green Building Council, IGBC submission – Public Consultation of the Review of Part L (Conservation of Fuel and Energy for Buildings other than Dwellings) 2017, NZEB-consultation-Final.pdf (Access 02 June 2017)


Mona Holtkoetter 2017.indd 9

07/01/2018 14:42

Enhance your career prospects —

Join CIBSE Ireland CIBSE Ireland promotes the careers of building services engineers by accrediting courses of study in higher education. It also approves work-based training programmes and provides routes to full professional registration and membership, including Chartered Engineer, Incorporated Engineer and Engineering Technician. ?PM\PMZI[\]LMV\UMUJMZWZN]TTaY]ITQÅML+1*;-W‫ٺ‬MZ[ a range of services, all focused on maintaining and enhancing professional excellence throughout your career. CIBSE members in Ireland are represented by an active Regional Committee that organises an extensive programme of CPD events, technical evenings, training courses and an annual conference. The programme also includes social events such as the annual golf outing and the annual Christmas lunch. CIBSE Ireland also hosts a number of awards each year, in collaboration with the Dublin Institute of Technology. These include the Young Lighter and Irish Lighter competitions, the Student Awards, and the Sustainable Design and Research Awards (SDAR Awards). CIBSE Ireland membership means you can avail of all these events and activities, and is complemented by direct online access to CIBSE’s full range of design guides and other publications. Email:

CIBSE Enhance Career Advert 2016.indd 1

07/01/2018 14:47

Enhancing Thermal Mass Performance of Concrete

Energy Audit of a Fitness/Leisure Centre

Paul Wynne


Eoin McLean


Paul Wynne 2017.indd 1

07/01/2018 15:23

SDAR Journal 2017


1. Introduction

This paper aims to investigate the energy performance of

Buildings represent the largest energy-consuming sector in the economy, accounting for over one-third of all final energy and half of global electricity consumed (IEA, 2013). As a result, buildings are also responsible for approximately one-third of global carbon emissions. With an expected population increase of 2.5 billion people by 2050, and given improvements in economic development and living standards, energy use in the buildings sector is set to rise sharply, placing additional pressure on energy availability (IEA, 2016).

a fitness/leisure centre. A detailed energy audit has been conducted to determine the energy consumption of the building. Through the collection and analysis of data, the energy performance and Energy Performance Indicators (EnPIs) have been identified. This research indicates that an energy audit can lead to identifying significant energy savings potential in a building. Energy saving opportunities have been identified with a potential to save 158,906kWh of electricity, 81,201kg of CO2 and potentially saving up to F51,230 per annum. A combined heat and power (CHP) plant could yield savings of up to F28,522 annually. A lighting upgrade offers potential savings of 122,976kWh of electricity and F19,373 annually. Due to their high energy demand, commercial buildings have the potential for significant energy savings. The fitness centre was built in 2004 to a high standard and is a well maintained building. Nevertheless, this paper demonstrates the significant potential for energy reduction in buildings such as fitness centres. Keywords Energy audit, energy monitoring system, significant energy user. Glossary EMS

Energy Monitoring System


Energy Performance Indicators

Figure 1. Final energy consumption by sector and buildings energy mix, 2010 (IEA, 2013)

Figure 1 indicates that buildings consumed 35% of final energy consumption in 2010 and electricity consumption made up 30% of this. Due to high losses in the generation and transmission of electricity, any savings in the building sector will translate into greater savings in primary energy use in the power sector, and a greater reduction in CO2 emissions. This research demonstrates that energy efficiency and low-carbon technologies can play a vital role in the energy revolution needed to bring about a reduction in our dependence on fossil fuels and reduce carbon emissions. This paper will outline a structured approach to conducting an energy audit to the international standard ISO 50002. The key objectives of this paper are to:

HVAC Heating Ventilation and Air Conditioning

• Identify and document all energy-consuming equipment in the building;


International Energy Agency

• Collect data from existing metering, utility bills and data loggers;


Kilowatt hour

• Analyse data and breakdown consumption by use and source;


Sustainable Energy Authority Ireland


• Identify a historical pattern of energy performance;

Significant Energy User

• Identify Significant Energy Users (SEUs) and Energy Performance Indicators (EnPIs); • Identify energy improvement opportunities; • Evaluate and rank energy performance opportunities (ISO 50002, 2014).

2. Background The fitness centre considered here was built in 2004 and has a total floor area of 2787m2. The building is a lightweight, steel-framed structure with metal decking roof and side walls.


Paul Wynne 2017.indd 2

07/01/2018 15:23

Energy Audit of a Fitness/Leisure Centre

The ground floor includes the double height main swimming pool, reception, offices and changing areas. A cardio fitness theatre, aerobics studio, weights area and spinning studio are located on the first floor. The second floor has a performance lifting area, strength training area and weights area. The building also includes a basement underground carpark. The main facilities and areas are as follows: • 25m stainless steel swimming pool; • Jacuuzi; • Male and female steam room and sauna; • Fully equipped gymnasium; • Cardio fitness theatre; • Large aerobics studio; • Spinning studio. The international standard ISO 50002 specifies the principles governing carrying out of energy audits, the requirements for the common processes during energy audits, and the deliverables for energy audits. It includes a series of annexes that address different types of audits for industry, buildings, transportation and services. Audits include essential information on current energy use and performance and recommendations for improvements in a wide range of areas, including operational controls, maintenance controls, modifications and capital projects. The energy audit process consists of the following stages, as illustrated in Figure 2:

• • • •

MCC2 – air handling units; MCC3 – pool plant; Ground floor distribution board Air conditioning – Condenser No:1 and condenser No: 2, first floor; • Main gas meter; • Main water meter; • DHW water meter. 3.3 Conducting the site visit The author conducted site visits initially to document all energyconsuming systems and equipment in the building. The equipment was categorised into the following areas: • HVAC equipment; • Lighting; • Other energy-using equipment. Access to the as-built drawings and operation and maintenance manuals was provided by the manager which facilitated the equipment lists. Subsequent site visits were conducted to detail historical and current energy performance data. Access was provided to gas and electricity bills for 2014 – 2015 and to the EMS.

4. Energy Consumption 4.1 Energy use Gas and electricity are the primary energy sources in the building with monthly bills generated from the gas and electricity meters on site. Table 1 summarises the gas and electricity usage for 2014 and 2015. Table 1: Energy use

Figure 2. Figure 2: Energy audit process flow diagram. (ISO 50002, 2014)

The standard states that the content of the report shall be appropriate to the defined energy audit scope, boundaries and objectives of the energy audit.

3. Methodology 3.1 Scope of the audit This report details the electrical and thermal energy-consuming equipment throughout the building. The report is aligned with the requirements and methods detailed in the Energy Efficiency Directive, EN-16247-2 Energy Audits-Buildings. The report also details the energy baseline and Energy Performance Indicators (EnPIs) to facilitate the measurement and verification. 3.2 Data collection Energy data use has been obtained from the electricity bills and from the gas bills (daily data). A data logger was installed on the sauna/ steam room distribution board. Sub-metering data was available on site through an energy monitoring system (EMS) and provided a breakdown of the electricity consumption into the following areas:

Leisure Centre – Energy Use 2014kWh/yr Gas

2014kF/yr 2015kWh/yr


1,085,932 F48,359.39 1,170,274 F44,260.61


662,538 F108,568.27 690,759 F111,067.88


1,748,470 €156,927.66 1,861,033 €155,328.49

The gas usage has remained relatively stable with an increase in 2015 of 7.8% compared to 2014. It can be seen from Table 1 that even though the gas consumption slightly increased, the annual cost reduced slightly. This was due to the manager moving to a new supplier and obtaining a better tariff near the end of 2014. Figure 3 shows the total energy consumed in the building in 2015 was 1,861,033kWh and is made up of 63% gas consumption and 37% electricity. Figure 4 indicates that electricity represents 72% of the annual energy cost but only consumes 37% of the energy. Monthly electricity usage for 2014 and 2015, shown in Figure 5, displays consistent consumption with a slight increase over the summer months, indicating an increase in air conditioning (AC) use.


Paul Wynne 2017.indd 3

07/01/2018 15:23

SDAR Journal 2017

Figure 3. Energy use breakdown Figure 7. Monthly gas consumption 2014 and 2015

Figure 6 is a screenshot from the EMS which shows the increase in consumption on the distribution board from 2014 to 2015. This was discussed with the building manager but he was not aware of any reason to explain this sudden increase. It is possible during an AC maintenance visit a previously not working piece of equipment was repaired. This situation highlights the importance of continuous energy monitoring.

Figure 4. Energy use cost breakdown

Monthly gas consumption for 2014 and 2015 in Figure 7 displays reasonable consistent consumption with the exception of August 2015. There is no obvious explanation for the increase in consumption in August. It could be expected that there might have been an increase in visitor numbers, which in turn would increase hot water consumption, but this is not the case as visitor numbers were lower than in July. 4.2 Data collection and sources

Figure 5. Monthly electricity consumption 2014 and 2015

The gas and electricity consumption data was collected from the supplier’s bills for 2014 and 2015 and was obtained from the fitness/ leisure centre manager. A breakdown of electricity consumption was obtained from the EMS. The weather data (degree days) was obtained from the website Data relating to visitor numbers, opening hours and operating times were obtained from the manager. A datalogger was installed on the sauna/steamroom and an ammeter was used to estimate the loads of all other unmetered loads at the main distribution board. 4.3 Metering arrangements

Figure 6. Increase in consumption on the ground floor distribution board

Through the data analysis it was found that the increase in electricity consumption was due to a marked increase in consumption on the ground floor distribution board in 2014. The average daily consumption up to 24/04/2014 was 38kWh. From 25/04/2014 to 31/12/2015 the average daily consumption was 308kWh.

The building contains an EMS, which measures the following areas: • Ground floor distribution board; • Air conditioning; • MCC-02 Air handling units; • Pool plant room control panel; • Main electricity incomer; • Main gas meter; • Main water meter; • DHW water meter. The system is viewed on the manager’s PC and allows access to live and historical consumption data. The system allows the manager to monitor the electricity and gas consumption and to compare each month.


Paul Wynne 2017.indd 4

07/01/2018 15:23

Energy Audit of a Fitness/Leisure Centre

metered totals and the estimated totals for 2015. An ammeter was used to estimate the loads on all the unmetered circuits.

Table 2: Main Distribution Board MCCB No. Description

Metered kWh

Estimated kWh


AC Condenser No.2 First FLoor


Lettable Unit 2: Lads Lounge



Sauna and Steam Rooms




No Load


AC Condenser No.1 First FLoor Incl in No.1


Fire Alarm




Basement DIstribution Board



MCC-01 Boilerhouse






MCC-03 Pool Plantroom



First Floor DIstribution Board


Ground Floor DIstribution Board 114,725


Second Floor DIstribution Board






Lettable Unit 1: Cafe




Figure 8 groups together the circuits from Table 2 into appropriate categories, i.e. AC, AHUs and MCC-01 into HVAC, and the distribution boards into lighting and general services.Figure 8 indicates that one of the significant energy users is the sauna/steam room, consuming an estimated 10% of the annual total. The combined HVAC total consumes 21% and the pool plantroom consumes 8%. The lighting and general services for the building accounts for 46% of the total. There are AC condenser units fitted in the basement car park which, in all probability, are connected to the basement distribution board.

No Load

Actual Electricty Consumption 690,759kWh



Table 3: Sauna and steam room daily consumption Sauna and Steam Room kWh (L1) kWh (L2) kWh (L3) Total kWh 06/03/2016



































Datalogger Daily kWh - Sauna/Steamroom


250 200

Using the data available from the EMS for 2015, it can be seen that the total electricity consumption from the four sub-metered areas – ground floor distribution board, MCC-02 air handling units, MCC-03 pool plantroom and the air conditioning – totalled 280,535kWh out of a total of 690,759kWh. This figure only accounts for 41.0% of electricity consumption in 2015. The building manager was not aware of this and was surprised to discover the extent of the energy consumption missing. The main distribution board is located in the basement switch room. Table 2 details the circuits and the


4.4 Breakdown of energy use

150 100 50 0

Figure 9. Datalogger daily kWh for the sauna/steam room

This is leading to a misrepresentation of the energy readings on the EMS as it is not accounting for a sizeable AC load. 4.5 Significant energy user The data obtained from the data logger installed on site to measure the electricity consumption of the sauna/steam room distribution board is detailed in Table 3. The total consumption recorded for the week beginning the 06/03/2015 was 1,351kWh, and the annual consumption is estimated to be 70,237kWh, (1,351 x 52weeks).

Figure 8. Categorised breakdown of electricity 2015

Figure 9 shows the daily electricity consumption obtained from the data logger. The load is consistent during the week and drops off at the weekend due to shorter opening hours. The sauna and steam room distribution board consumes an estimated 10% of the total annual energy.


Paul Wynne 2017.indd 5

07/01/2018 15:23

SDAR Journal 2017

Electrical Winter Profile 2015

Figure 12. Gas consumption/degree days 2014.

Figure 10. Winter weekly profile 2015. Electrical Summer Profile 2015 140 120


100 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Mon-Thur




Figure 13. Gas consumption/degree days 2015. Figure 11. Summer weekly profile 2015.

4.6 Profile of energy consumption Figure 10 shows the main incoming load profile for the week beginning 02/11/2015 for different opening hours. It can be seen that the overall load ramps up steeply when the main plant is switched on at 05.30 and plateaus during the day at a consistent 120kWh. The longer opening hours from Monday to Friday are easily identified on the graph. Figure 11 shows the summer profile for the week beginning 06/04/2015 and follows a similar pattern to the winter.

5. Analysis and baseline There is a large thermal demand for the swimming pool, space heating and hot water. The parameter “degree days” will affect the energy use, as a lower outside temperature will increase heat loss and requires more energy to warm up the building and the swimming pool. The indicator “opening hours” will also affect the energy use. The following independent variables are used to analyse the variation of the energy use for 2014 and 2015 and to derive Energy Performance Indicators (EnPIs): • Degree days base 15.5°C; • Opening hours; • Number of visitors. 5.1 Analysis of gas consumption The gas consumption is compared to degree days (base 15.5°C) for 2014 and 2015. An XY scatter diagram was gen-erated with the degree days on the x axis and the gas con-sumption on the y axis, as shown in Figure 12 and Figure 13. By adding a trendline, it can

Figure 14. Electricity use vs opening hours.

be seen that when the monthly values are plotted, they fit close to the line. There is very good correlation for both years, with a better correlation in 2014 with an R2 value of 0.9564 compared to 0.8711 for 2015. In 2014, the equation of the line: y = 220.58x + 54263 gives the base load of the building as 52,463kWh month and states that for every increase of one degree day that another 220.58kWh of gas will be consumed. In 2015, the equation of the line: y = 2208.39x + 58727 gives the base load of the building as 52,463kWh month and states that for every increase of one degree day that another 220.58kWh of gas will be consumed. As can be seen from Figure 14, two months fall outside the line. Less gas than expected was used in July while in August more gas than expected was used. This issue was discussed with the building manager but there


Paul Wynne 2017.indd 6

07/01/2018 15:23

Energy Audit of a Fitness/Leisure Centre

Table 4: Proposed energy efficiency measures Measure

Potential Electricity Saved kWh/Yr

Potential Carbon Saved kg Co2/kWh

Approx. Installed Cost €

Potential Cost Savings €/Yr

Approx. Payback Period



Install VSDs on pool AHU







Preheat water to steamroom






Based on 414 litres per week of water usage per generator


Upgrade pool heating pump-set 25,316





Based on upgrade and pressure sensor installation


CHP option 1 GG70 CHP option 2 GG50

– –

€125,000 €116,000

€41,958 €28,522

2.6 3.6

Based on 5,200 hours pa Based on 5,200 hours pa


LED lighting upgrade





– – 122,976

was no obvious reason he knew of for the unexpected gas usage. The manager has had ongoing issues with two of the four boilers and is in the process of installing two new condensing boilers.

excess of 85% due to utilisation of heat from electricity generation and the avoidance of transmission losses because electricity is generated onsite.

5.2 Analysis of electricity consumption

Bills analysis – gas

There is no clear correlation between electricity consumption and the three independent variables.

The gas consumption and unit costs for 2015 were calculated and the average hourly gas consumption over 24 hours was 133kWh, and the average unit rate was 3.83c/kWh. Assuming that the efficiency of the boilers is 80%, then the average annual heat load is calculated at 107kWth. Therefore, a CHP of approximately 90/110kWth output is appropriately sized for this installation.

Figure 14 shows the relationship between the electricity use and the opening hours based on daily usage recorded on the 03/11/2015. The figure indicates poor correlation between electricity use and opening hours.

Bills analysis – electricity

6. Opportunities for improving energy performance The following is a discussion of the main opportunities for energy efficiency improvement, together with estimated costs, savings and payback periods. The opportunities in Table 4 are divided into two categories: I. Low Cost Measures (LCM) II. High Cost Measures (HCM) 6.1 Accelerated capital allowance (ACA)

The daytime base loads and unit costs were calculated for 2015. The average cost per daytime unit, including all transmission and service charges, was €0.164. For the basis of the CHP selection, a unit of 90kWe would be suitable. CHP selection The optimal electrical CHP size is 90kW and a thermal demand of approximately 90/110 kWh. Based on the available Sokatherm CHP units, the best fit is the GG70. This provides 71kWe and 114 kWth, with an overall efficiency of 90.7%.

• A company purchases a product;

Additionally, this would comply with the SEAI definition of high efficiency CHP (i.e. >75%) and would allow the fitness centre to claim back an annual carbon rebate of €3,278.

• In the accounting year of the product purchase, that product is listed as eligible for the ACA;

Economic Analysis 1 – CHP based on existing data

• When filing the corporation tax return for the year of product purchase, taxable income is reduced by the full amount of the product purchase.

• Capital cost


The project can avail of the ACA on proposed energy efficient measures totaling €162,714.

• Annual saving


• Carbon Tax Rebate


6.2 Combined heat and power (CHP)

• ACA Capital Write-off


CHP is a highly efficient energy solution that is suitable for buildings with a high thermal load. CHP is the simultaneous generation of usable heat and electricity in a single process. It can reach efficiencies in

• Payback time

2.6 years

• Net benefit after 5 years

€100,417 (includes initial capital cost incurred)

The ACA is a corporate tax reduction incentive. It works as follows:

The CHP unit specified is a Sokatherm GG70. If the unit was owned outright, then the figures obtained from Tables 5a and 5b are as follows:


Paul Wynne 2017.indd 7

07/01/2018 15:23

SDAR Journal 2017

Economic Analysis 2 – CHP based on estimated data after the lighting upgrade This economic analysis is based on the assumption that the lighting upgrade is installed before the purchase of the CHP. The lighting is estimated to save 122,976kWh annually. The CHP figures are average values of kWh in each month for day time units, which equates to 5,475 hours in a year. Therefore, the average saving with the lighting upgrade is (122,976/5,475) = 22.46kWh saving per

month. This would reduce the lowest figure in February of 87.83kWh to (87.83 – 22.46) 65.37kWh. A CHP sized <65.37kWh would be suitable. Based on the available Sokatherm CHP units, the best fit is the GG50. This provides 50kWe and 82 kWth, with an overall efficiency of 90.4%. If the unit was owned outright, then the figures are as follows:

Table 6a: CHP Financial Analysis 2

Table 5a: CHP financial analysis 1

CHP Financial Analysis: GG50.

CHP Financial Analysis: GG70. kWh

Cost F/kWh

Total F/kWh

Electricity displaced




Boiler fuel displaced



Boiler efficiency -80%

CHP fuel cost


Annual savings

Cost F/kWh

Total F/kWh

Electricity displaced




Boiler fuel displaced



Boiler efficiency -80%



Savings sub-total




CHP fuel cost


Maintenance costs per hour run

Maintenance costs per hour run

Net benefit


Sub-total CHP costs


Savings Sub-total

Sub-total CHP costs

Sub-total Savings




Annual hours

Sub-total savings




Net benefit

Annual savings

Year 0

Year 1 Year 2

Year 3 Year 4 Year 5


Savings sub-total



F5.59 F1.50

Sub-total CHP costs


Savings Sub-total

Sub-total CHP costs

Sub-total Savings




Annual hours

Sub-total savings




Table 6b: CHP installation financial appraisal 2

Table 5b: CHP installation financial appraisal 1 CHP installation financial appraisal:



CHP installation financial appraisal:

Year 0

Year 1 Year 2

Year 3 Year 4 Year 5


Expenditure CHP supply and commission


CHP supply and commission


Integration cost estimate


Integration cost estimate


Total expenditure


Total expenditure



F38,680 F38,680 F38,680 F38,680 F38,680


F26,177 F26,177 F26,177 F26,177 F26,177

Carbon rebate F0.00309 F3,278 F3,278 F3,278 F3,278 F3,278 F0.00309/kWh gas

Carbon rebate F0.00309 F2,346 F2,346 F2,346 F2,346 F2,346 F0.00309/kWh gas


ACA capital write-off



Total savings

F41,958 F41,958 F41,958 F41,958 F41,958

Total savings

F28,522 F28,522 F28,522 F28,522 F28,522

Net cash flow

F41,958 F41,958 F41,958 F41,958 F41,958

Net cash flow

F28,522 F28,522 F28,522 F28,522 F28,522

Cumulative cash flow -F125,000 -F67,417 -F25,458 F16,500 F58,458 F100,417

Cumulative cash flow -F116,000 -F72,978 -F44,455 -F15,933 F12,933 F42,112


Paul Wynne 2017.indd 8

07/01/2018 15:23

Energy Audit of a Fitness/Leisure Centre

• Capital cost


• Annual saving


• Carbon Tax Rebate


• ACA Capital Write-off


• Payback time

3.6 years

• Net benefit after 5 years

€41,112 (includes initial capital cost incurred)

6.3 LED lighting Lighting is estimated to account for over 20% of the total electricity consumed in the building. There are significant opportunities to realise energy savings through replacement of existing compact fluorescent fittings with new energy efficient LEDs. Figure 15. Categorised breakdown of electricity 2015

Table 7: LED lighting financial appraisal LED lighting financial appraisal:

Year 0

Year 1 Year 2

Year 3 Year 4 Year 5

Expenditure Investment


Annual costs

Total expenditure


Savings ACA capital write-off

F19,373 F26,177 F26,177 F26,177 F26,177 F5,358

Total savings

F19,373 F19,373 F19,373 F19,373 F19,373

Net cash flow

F19,373 F19,373 F19,373 F19,373 F19,373

Cumulative cash flow -F42.864 -F18,133 -F1,240 F20,613 F39,986 F59,359

The current lighting is estimated to consume 189,925kWh and costs €30,085 per annum. The proposed LED lighting is estimated to consume 66,949kWh and cost €10,712 per annum, resulting in energy savings of 122,976kWh per annum and financial savings of €19,373 per annum. The lighting analysis calculation used the average unit cost of electricity of €0.16. The LED lighting upgrade estimated costs are as follows: • LED fittings cost


• LED lighting installation


• Total capital cost


• ACA capital write-off


• Annual saving


Table 7 indicates a simple payback of 1.9 years with a cumulative cash flow at the end of year five of €59,359.

7. Summary The detailed energy audit of the energy consumption has revealed that the electrical and gas consumption is in line with CIBSE benchmarks for similar buildings (CIBSE, 2012). Figure 15 provides a breakdown of electricity consumption and

indicates that the lighting and general services distribution boards consume 46% of the total. HVAC accounts for 21% of the total consumption. The largest single energy user is the sauna and steam room distribution board, consuming 10% of the total. The detailed energy audit has identified that significant energy saving potential exists. The installation of a CHP plant and a lighting upgrade to LED fittings would significantly reduce energy consumption. Installation of a CHP plant can potentially save between €41,958 and €28,522 annually, based on Option 1 or 2. A lighting upgrade can potentially lead to savings of 122,976kWh of electricity and €19,373 of savings annually. It should be noted that these values are not cumulative. For example, if the CHP and lighting upgrade were installed, the total savings would not equal the two individual savings combined. The lighting upgrade would lower the annual electrical consumption which in turn would lower the performance of the CHP.

8. Conclusion The energy saving opportunities identified in this paper identified a potential savings of 104,981kg CO2 annually. Buildings are complex and have numerous energy-consuming systems. For the specific building considered in this research, there are air conditioning and air handling units, low-pressure hot water boilers, instantaneous hot water generators, swimming pool plant, and a building management system. This research shows submetering and an EMS are critical to the efficient operation of a building. The onsite EMS was a valuable asset allowing access to accurate real data on the building.

9. Discussion and recommendations This analysis suggests that providing the EMS to cover the sauna/ steam room, the basement distribution board, the second-floor distribution board and the café would be beneficial. Expanding the EMS will allow greater capture of the total electricity consumption and will facilitate verification of savings in the future. During discussions with the building manager, he mentioned that he finds it difficult to find time to review the data on the EMS. This


Paul Wynne 2017.indd 9

07/01/2018 15:23

SDAR Journal 2017

highlights the difficulty in controlling energy usage in buildings when the manager’s primary aim is obviously running the core business. It would seem, therefore, that such time constraints on managers/ owners of SMEs (at least in the context of a fitness centre) represents an opportunity for energy engineers to provide solutions for costeffective ways to continuously monitor energy and optimise energy consumption.

References CIBSE, 2012. Guide F: Energy Efficiency in Buildings. [Online]. EPBD Implementation Group, 2012. Action Plan for the Implemenation in Ireland of EPBD Recast. [Online] Available at: BuildingStandards/FileDownLoad,31057,en.pdf. [Accessed 20 February 2016]. IEA, 2013. Transition to Sustainable Buildings - Strategies and Opportunities to 2050. [Online] Available at: Buildings_2013.pdf [Accessed 6 February 2016]. ISO 50002, 2014. Energy audits – Requirements with guidance for use, Geneva: ISO. ISO, 2015. Evolution of ISO 50001 Certificates in Ireland. [Online] Available at: htm?certificate=ISO%2050001&countrycode=IE#standardpick [Accessed 10 February 2016]. SEAI, 2015. Annual Report 2015 on Public Sector Energy Efficiency Performance. [Online] Available at: Public_Sector/Annual-Report-2014-on-Public-Sector-Energy-EfficiencyPerformance-.pdf [Accessed 28 February 2016]. Sokatherm, 2016. Sokatherm. [Online] Available at: htcms/en/our-compact-chp-units-1/50-kw-class-1.html [Accessed 26 April 2016].


Paul Wynne 2017.indd 10

07/01/2018 15:23

Institiúd Teicneolaíochta Átha Cliath Dublin Institute of Technology School of Multidisciplinary Technologies College of Engineering & Built Environment The School of Multidisciplinary Technologies provides modules and programmes, at undergraduate and postgraduate levels, which link engineering and built environment disciplines for the design and operation of healthy, low-energy buildings and infrastructure for a modern sustainable world. These full-time and part-time courses are founded on a research base and promote multidisciplinary themes across the DIT and with external partners. Themes include energy, sustainability, engineering computing (applied technology), building information modelling and management (BIM), and educational research.

Undergraduate Programmes Bachelor of Engineering (Hons) Engineering (General Entry)

Full Time


Bachelor Engineering Technology (Ord) Engineering (General Entry)

Full Time


MSc in Applied Building Information Modelling and Management (aBIMM)

Part Time


Postgraduate Diploma in Collaborative BIM

Part Time


Part Time


Check out our video “DIT Engineering General Entry” on YouTube.

Postgraduate Programmes

Check out our video “BIM@DIT Promotion” on YouTube.

Research Programmes PhD and MPhil opportunities in areas such as Lighting, Energy Management, FT/PT BIM, collaborative Digital Construction, and Analytics/Computation/ Critical Digital Literacy for Engineering and Built Environment Applications

Contact School

CPD By successfully completing modules from our Postgraduate Suite in areas such as BIM and Applied Computing you can upskill in emerging aresa and progress your career through the award of standalone CPD certificates or through the accumulation of credits into postgraduate awards. Review our available modules on: Review our available modules on: and

Please contact us if you have any queries about our programmes, research, or other activities. School Administrator: Jane Cullen. Tel: 01 – 402 4014. email:

Untitled-8 1

08/11/2016 14:28

fastrack to the top Join

CIBSE Ireland Boost your work opportunities by joining the group of relevance

You need to be in the room with the group that supports your designs, accredits your course and sets the highest standards for your industry New Cibse Advert 1.indd 1

10/11/2016 08:40

Enhancing Thermal Mass Performance of Concrete

A case study of the Omani electricity network and readiness for solar energy integration


Eugene Coyle 2017.indd 1

07/01/2018 15:31

SDAR Journal 2017

Abstract In this paper a study is made of the electricity network of the


Sultanate of Oman. The electricity industry of Oman currently

PV Solar, CSP, Roof-top Solar, Solar EOR, Wind Energy,

relies on almost 100% fossil fuels – with natural gas (97.5%)

GCC Interconnector, Renewable Pilot Projects.

and diesel oil (2.5%) being the primary sources of electricity generation. This reliance is expected to change significantly in


the coming years. Harnessing solar energy (and wind energy)


Concentrated Solar Power

will help to significantly reduce the country’s carbon emission


Total Primary Energy Supply

footprint whilst enhancing intra-structural development and

WMO World Meteorological Association

ensuring economic stability.

MECA Ministry of Environment and Climate Affairs

Solar energy density levels in Oman are among the highest in the world. The country receives an extensive daily solar radiation of 5,500-6,000 Wh/m2 per day in July and 2,5003,000 Wh/m2 per day in January. With careful planning this energy rich resource may now be harnessed. In this context the regulatory environment in Oman has been gradually trans-forming to minimise the political and administrative barriers for the integration of renewable energies into the Omani electricity and water system networks.


Enhanced Oil Recovery


Solar Enhanced Oil Recovery


Petroleum Development Oman

OCGT Open Cycle Gas Turbine CCGT

Combined Cycle Gas Turbine


Main Interconnected System (Oman)

OPWC Oman Power and Water Company GCCIA Gulf Cooperation Countries Interconnection Authority IPP

Independent Power Projects

A number of detailed studies have been conducted in scoping


Independent Water Projects

potential developments for solar energy resources across

OPWP Oman Power and Water Procurement Company

Oman. These include (i) a proposal for wide-scale deployment


Total Power Generation Resources

of domestic roof-top PV solar, (ii) feasibility of large-scale


Dhofar Power System

generation plant by solar PV and/or Concentrated Solar


Directorate General of Water

Power (CSP), and solar thermal as an enhanced oil recovery


Oman Electricity Transmission Company

(EOR) assist. Wind generation is also feasible in a number of

RAECO Rural Areas Electricity Company of Oman

regional zones, with one approved development for a large

PAEW Public Authority of Electricity and Water

wind farm in the south of the country.

IRENA International Renewable Energy Agency

Oman is also connected to its Gulf Cooperation Countries


Renewable Readiness Assessment

(GCC) neighbouring countries via the Gulf Super Grid. This


Global Horizontal Irradiance

is a very important development both for the country and


Direct Norman Irradiance

for the wider region. With further developments in regional

MENA Middle East and North Africa Region

renewable energy generation, prospects for transmission


Direct Norman Irradiance

of clean energy between GCC countries and beyond, will


Gulf Cooperation Countries

emerge. Oman has a dedicated Ministry for Environment and Climate Affairs (MECA). A target of 10% renewable generation by 2020 is already in place. Creation of enhanced renewable governance structures, provision of renewable tariff support, investment planning, and strategic forward planning, are matters for ongoing review. 34

Eugene Coyle 2017.indd 2

07/01/2018 15:31

A case study of the Omani electricity network and readiness for solar energy integration

1. Introduction 1.1 Introduction to Oman One of the six Gulf Cooperation Countries (GCC), the Sultanate of Oman is a small, stable and prosperous nation of the Middle East. It is located between the Persian Gulf and the Arabian Sea, bordering the United Arab Emirates to the northwest, Saudi Arabia to the west and Yemen to the southwest (see Figure 1). Oman is the third largest country in the Arabian Peninsula, with a land area of 310,000 km2. Hosting eleven regional governates[i], the principal population and administrative centre is located in Muscat and its northern surrounds, with other principal cities at Sohar, Sur, and Salalah to the south. Oman’s coastline extends 1,700 kilometres from the Strait of Hormuz in the north to the Yemeni border in the southwest. The country’s central plain is mainly desert (the famed “empty quarter” and home to rich oil reserves), with varied geographic features including the mountainous Hajjar range which covers 15% of the country’s landmass. Experiencing extremely hot temperatures (40°C+) particularly in inland regions for up to eight months of the year, Oman’s largely coastal population benefits from sea breezes and much milder temperatures through the month of October to February [1]. The combined population of Oman is estimated to be 4.5 million, comprising approximately 2.5 million native Omanis and 2 million expatriates.

societal infrastructural development [6]. Oman also ranked highly as a nation at peace in the 2016 Institute for Economics & Global Peace Index, placed at No: 5 in the Middle East and North African region and 59 in the overall world ranking [7]. Since 1970 the country has maintained 5-year (short term) and 25 year (longer term) strategic plans. This has enabled Oman to make effective use of its people and resources through various stages of development and opportunity, thus meriting the international recognition it has earned over the past half century. Oil exploration in Oman commenced in the 1960s, resulting in the first extraction of oil as a natural resource in 1967. With current reserves of approximately 5 million barrels, Oman ranks 25th among world oil-producing nations [8]. The Total Primary Energy Supply (TPES) of the Sultanate is dependent on natural gas and oil. In 2014 the share of TPES was 80.7% natural gas and 19.3% oil. Oil consumption is mainly confined to the domestic market catering for industrial processes and an expanding vehicle fleet. Oil use in electricity generation is limited to rural off-grid generation plants. Natural gas is increasingly deployed in electricity generation, desalination and industrial use, including enhanced oil recovery (EOR) in the oil and gas sector. Gas revenue has increasingly been a driving source for the economy. In 2012, for example, natural gas exports accounted for 38% of production [2], [3], [4]. Petroleum Development Oman (PDO) is Oman’s primary exploration and production company, accounting for 70% of crude oil production and almost all of its natural gas production (130 fields with 600 wells). Table 1 provides a list of principal Oman Data Indicators. Table 1: Oman data indicators Oman Key Energy Indicators 2014 Population [ii] (millions) (Feb 2017) Expatriates (2.1m), Native Omanis (2,47m).


GDP (billion US$)


Energy Production (Mtoe)


Net Imports (Mtoe)


Electricity Consumption (TWh) CO2 Emissions (Mt of CO2)

26 59.9

2. Omani electricity network

Figure 1. Map of Sultanate of Oman and Neighbouring Countries (Magellan Geographix Atlas).

The United Nations Development Report (UNDP) 2010 placed Oman number one in the world in the Human Development Index ranking, a formidable recognition which aligns with the steady growth and advancement in health and education, and people and

Oman’s generation network is powered almost entirely (97.5%) by natural gas, principally using Open Cycle Gas Turbine (OCGT) plants. Combined Cycle Gas Turbines (CCGT) have also been designed for combined electricity production and water desalination. The remaining 2.5% of generation is through diesel engine generators. Owing to its topography, Oman does not have a single interconnected grid. The principal network or “Main Interconnected System” (MIS), located in the north of Oman, services Muscat and six other governates, totaling upwards to one million customers. The MIS is owned by the Oman Electricity Network Company (OENC) and comprises a number of power generating facilities, owned and


Eugene Coyle 2017.indd 3

07/01/2018 15:31

SDAR Journal 2017

operated by various companies, in addition to the 400/220/132kV transmission grid and three distribution network operators who act as licensed electricity suppliers. The MIS is interconnected to the power system of Petroleum Development Oman (PDO)[iii] through a 132kV link at Nizwa, to the Emirate of Abu Dhabi through a 220kV link at Mahadha, and to other member states of the GCC Interconnection Authority (GCCIA). Several of the power generation facilities connected to the MIS produce desalinated water in conjunction with electricity [iv]. The Oman Power and Water Company (OPWC) is responsible for the purchase of power and water for all Independent Power Projects (IPP) and Independent Water Projects (IWP) in Oman [iv]. OPWP undertakes long-term generation planning and publishes a 7-year statement. Total Power Generation Resources (TPGR) of the MIS system stands at 7800MW (2016/17), with the expectation of reaching 11000MW by 2020 [10]. In respect of water desalination plant, MIS has a current capacity of 900,000 m3/d, with an expected capacity of 1,500,000 m3/d by 2020. In the south of Oman the Dhofar Power System (DPS) is a much smaller network, serving 92,500 consumers in the Salalah and surrounding outlying areas. The DPS has two generating facilities, a 220kV/132kV transmission grid (owned and operated by OETC), and a distribution network which is owned and operated by the DPC. The Dhofar Power System is interconnected with the power system of Petroleum Development Oman (PDO), via a 132kV link between Thumrait and Harweel[vi], with a transfer capacity of 150MW. The Directorate General of Water (DGW) is the principal authority for potable water supplies and distribution in the Governate of Dhofar where a single water desalination plant is the principal source of water. TPGR for the DPS are expected to reach 1600MW in 2017, rising to 2500MW by 2020 [3], [4], [10]. Ad Duqm is located on the eastern coastline of the Al-Wusta region, halfway between the MIS and the DPS. With a small population of 9000 people, the region is entering a rapid growth period owing to the development of a new economic and industrial centre. The region is currently served by a small integrated system owned and operated by the Rural Areas Electricity Company of Oman (RAECO). A 67MW diesel-fuelled power plant supplies the grid, with a second 80MW plant planned for 2018 [3], [10]. The Musandum Governate is an enclave of Oman, located in the northern-most region, separated from the main landmass by the United Arab Emirates, and extending into the Strait of Hormuz. With a population of 39,000, the Musandum Governate is supplied by a number of small diesel generators, with procurement for a further 120 MW [4], [10]. 2.1 GCC Interconnector As a GCC member state Oman benefits as a contributing partner to the “Power of Six” Gulf Super Grid. The grid was developed in three phases and is managed by the GCC Interconnection Authority (GCCIA). The connector comprises a 400kV transmission network enabling power transfer between the six GCC countries — Saudi Arabia, UAE, Qatar, Bahrain, Kuwait and Oman. Phase I of the project enabled connection between Bahrain, Kuwait, Saudi Arabia and Qatar. Phase II achieved integration of the UAE and Oman

power systems. Phase III linked the networks of Kuwait, Saudi Arabia, Bahrain, Qatar (North Grid) and the United Arab Emirates and Oman (South Grid). This resulted in the construction of six (ABB) 400kV gas insulated substations, a High Voltage Direct Current (HVDC) converter, 830 kilometers of double-circuit 400kV transmission lines, and approximately 50 kilometers of land and submarine cable. The HVDC link enables power flow between the Saudi Arabia grid, which operates at 60Hz, and the other five states, which operate at 50Hz [11]. 2.2 Tariff Subsidies Electricity provision in Oman is highly subsided, and is equally priced to end-users in all locations throughout the Sultanate. Financial subsidies by the government to licensed suppliers ensures prices to consumers are kept well below the generation, transmission and distribution costs (direct financial subsidies). Indirect subsidies to electricity producers have also ensured low prices on natural gas and diesel fuel. In 2012 the average subsidy was 42% and upwards to 80% in rural jurisdictions. It is proposed that the financial subsidy to electricity in rural areas is higher than the projected generation costs of solar PV. In addition to subsidies to the domestic population, low gas prices have been a major driving force towards economic growth and diversification in the Sultanate [3], [4].

3. Overview of renewable energy feasibility studies 3.1 Solar feasability studies Indicative levels of solar radiation in Oman for the months of January and July are shown in Figure 2. Levels are among the highest in the world. Several studies have been carried out on behalf of the Oman Public Authority for Electricity and Water (PAEW) in determining the country’s suitability and readiness for diversification to renewable energy generation [5]. A study review of solar technologies, including concentrated solar thermal power technologies (parabolic trough, power trough, and linear Fresnel reflector), photovoltaic technologies (monocrystalline and polycrystalline cells, thin-film modules, inverters, mounting structures, axial tracking), and concentrating photovoltaics (similar to PV but utilising optical concentrators to concentrate sunlight from a broad collection area onto a small area of active semiconductor photovoltaic cell material) was completed in 2010 [12]. Examples of large-scale projects based on related technologies include installations in the US, Spain, Portugal, Germany, South Korea, Greece, China and India. For CSP plant, thermal energy storage and natural gas co-firing mechanisms are considered. Worley Parsons recommended co-firing over thermal energy storage for CSP plant installations in Oman. It was further recommended that CSP through CSP tower and direct steam generation and flat plate PV, be considered depending upon site conditions and suitability. Design capacity ranges of 80MW to 100MW are recommended for stand-alone CSP plant. For flat plate photovoltaic plant, a capacity limit of 50MW, has been recommended.


Eugene Coyle 2017.indd 4

07/01/2018 15:31

A case study of the Omani electricity network and readiness for solar energy integration

Figure 2. Oman: Solar Radiation January and July (retrieved from [3].

3.2 Renewable Readiness Assessment Study A Renewable Readiness Assessment (RRA) completed by the International Renewal Energy Agency (IRENA) has further investigated the case for diversification to solar and wind energy in the Sultanate [3]. In determining suitability for solar generation, average daily sunshine duration and solar radiation data has been amassed for different locations in Oman, deemed among the best in the world. Locations of highest solar radiation include Marmul, Fahud, Sohar and Qairoon Hairiti. Most other areas have similarly-good radiation levels except for Salalah and Sur, which have significantly lower insolation owing to the summer Khareef (rainy season) in Salalah and on account of frequent fog in the Sur region [vii}. Mappings of Global Horizontal Irradiance (GHI: total amount of shortwave radiation received from above by a surface horizontal to the ground), and Direct Normal Irradiance (DNI: radiation approaching in a straight line from the direction of the sun from its current position in the sky) are shown in Figure 2. From a study of 23 locations identified as suitable for large solar projects, four have been highlighted to have significant potential. These include Adam, Managh, Al Khaboura and Ibri. Land evaluations have been completed and tenders are being prepared. Future projects at Adam and Managh may be large-scale programs in the 100MW200MW range. 3.3 Roof-top Solar Study A technical study on the potential for rooftop solar PV in Oman forms the basis for evaluation of the wide-scale utilisation of domestic solar generation with grid connectivity [13]. The study estimates that there may be upwards to 25 km2 of roof area in the Sultanate with technical potential of 1.4GWp (gigawatt peak) for installed roof-top PV power. With an average irradiation resource of 2240 kWh/m3, the average PV system yield was estimated to be 1750 kWh/kWp (kilowatt peak). With an expected variation in PV system yield throughout the country and accounting for all typical module orientations of ± 10%, this offers an attractive proposition in forward energy planning. If fully exploitable, in excess of 2TWh of annual electricity production from domestic PV systems, could be realisable. In order to effect implementation, two PV system cost scenarios were articulated. Based on previous experience in Germany, a commencement system price of 3300 $/kWp was proposed. Following a period of five years of market development, a system

price of 1900 $/kWp, may attain. This analysis catered for a Feed-in Tariff (FIT) of 17.5 cUS$/KWh for small residential PV systems (of 10 to 15 kWp). The study considers roof-top size of 100m2 to 200m2, with PV sizes ranging from 5kWp to 11kWp, which is equivalent to 30 to 70 standard crystalline silicon and one (or two) inverters. In terms of PV modules for grid access, a regulatory framework permits a household to produce electricity and to sell it, with appropriate FIT in place. Binding rules on grid access will be required in order to effect implementation by the distribution system operators. In order to implement a pilot phase an appropriately trained team will be required. PV Panel Dimensions Roof-top size of 100 m2 to 200 m2, with PV sizes ranging from 5 kWp to 11 kWp which is equivalent to 30 to 70 standard crystalline silicon and one (or two) inverters Feed-in Tariff (FIT) of 17.5 cUS$/KWh for small residential PV systems (of 10 to 15 kWp)

4. Examples of renewable projects in Oman 4.1 Solar enhanced oil recovery The key factor determining an area’s suitability for concentrated solar power production is the Direct Normal Irradiance (DNI) value. In Oman the GAC estimate that this amounts to 2200kWh per m2 per year, which could yield 19404TWh of electricity per year. In addition to the application of electricity generation, solar energy has become an assist technology with other industrial applications. One such application is that of thermal Enhanced Oil Recovery (EOR), a process wherein steam (created by solar concentration) is injected into a reservoir and, in so doing, enhances the flow and oil production. Petroleum Development Oman (PDO) – in partnership with the renewable energy design company GlassPoint – has developed an enclosed trough technology housing thin curved mirrors inside a greenhouse. The mirrors track the sun throughout the day, focusing heat on pipes containing oilfield water. The concentrated sunlight boils the water to generate steam, which is then injected into the oil reservoir to enhance mobility. Steam injection increases the rate of oil production and can extend the lifetime of an oil field. The greenhouse protects the mirrors from high winds and blowing sand and dust. It has an automated washing machine to maintain optimal performance even in harsh oilfield desert conditions. By bringing the solar collectors indoors, the company has achieved a number of capital and operating cost reductions compared to exposed

Figure 4a. Thermal Enhanced Oil Recovery (EOR) PDO-GlassPoint (retrieved from [14].


Eugene Coyle 2017.indd 5

07/01/2018 15:31

SDAR Journal 2017

solar thermal designs. As a result, the solar steam generators can produce steam at costs that are competitive to natural gas in many oil-producing regions [14]. The project utilises a 7MW solar array to produce 11 tons/hour of high pressure steam which will be used to extract 33,000 barrels of oil, in addition to providing reserve plant heating. Features • Enclosed trough technology housing thin curved mirrors inside a greenhouse • Automated greenhouse spray cleansing system(1) • Mirrors track sun throughout the day, focusing heat on oilfield water pipes(2) • The steam generated is injected into the oil reservoir to enhance mobility • 7 MW solar array produces 11 tons/hour of high pressure steam

region. Other planned developments include 2000kW of solar projects in the Dhofar and Wusta regions. Other small-scale projects approved by the Authority for Electricity Regulation (AER) include a 100kW solar project at Hiji, a 290kW project at Al Mazyonah, 28kW solar project at Al Mathfa incorporating battery storage capability, a 500kW wind project at Masirah Island, and 4200kW wind projects at Saih Al Khairat, Wilyiat and Thumrait [3], [10], [18]. 4.3 Dhofar Wind Energy Farm In tandem with solar energy studies, a number of wind energy studies have been conducted to determine the wind energy resource potential across the Sultanate. Studies conducted confirm that coastal and southern regions of Oman are promising areas for wind energy generation, with typical average wind speeds of 5m/s and 2500 peak operational hours per year recorded [4], [19] (see Figure 5). Abu Dhabi’s renewable energy company, Masdar, signed a joint development agreement with RAECO in 2014 to design and build a 50MW wind farm, with location at Harweel in the Dhofar Governate. With contract cost in the region of $125M, this will be the first largescale wind farm in the GCC. The project is estimated to generate enough clean electricity to power 16,000 homes and mitigate 110,000 tons of CO2 per year [14]. It will be capable of delivering 50% of the Dhofar region electricity needs during the winter months. The development will comprise of 15 to 25 turbines, with energy ratings of 3.0 to 3.2MW, and a height of 120m.

Figure 4b. System schematic – solar tracking curved mirrors enclosed in greenhouse.

4.2 Renewable Energy Pilot Projects in Oman

5. Salient opportunities for national and and regional renewalable energy deployment

The Rural Areas Electricity Company of Oman (RAECO) accepted the remit for a number of renewable projects, including a 4700kW wind project at Masirah Island, and at Sharqia and Al Khariat in the Dhofar

A review by the Oxford Institute for Energy Studies subscribes to the growing belief that renewable energy, in particular wind and solar energy, can offer the MENA region a viable alternative to fossil

Figure 5. Oman, Location Wind Speed Recordings (retrieved from [3].


Eugene Coyle 2017.indd 6

07/01/2018 15:31

A case study of the Omani electricity network and readiness for solar energy integration

fuels in power generation [15]. Given the available landmass area and insolation richness, the opportunity now exists to make serious inroads in moving from crude oil and natural gas to renewable energy technologies. A cost-competitive environment for enhancement of renewables has now been presented. Although the crude oil market has stabilised at approximately $55 per barrel, it is not likely that prices will return to their earlier lofty levels. Oil producing countries, not least Saudi Arabia, are suffering the consequence with national income reductions of up to 50% of those of recent years. There is a requirement for structural reform of domestic energy market pricing. The opportunity is now available to address this requirement.

Public Authority for Electricity and Water approval, thus setting a benchmark for greater introduction of solar power to the nation’s energy mix. Three or four such projects, combined with further wind farm developments over the coming five to ten years, would be of significant import to Oman, both in terms of diversification to clean energy and a reduction of the emission footprint, and in marking Oman’s future intent as a lead country in renewal energy in the MENA region and beyond.

The important building blocks have already been taken in the MENA region, in particular as evidenced by the success of K. A. Care (King Abdullah City for Atomic and Renewable Energy), and Masdar (Abu Dhabi’s renewable energy city). K. A. Care is a state agency vested with the authority to initiate renewable energy deployment and create new institutions as required for policy implementation. Masdar is also a sustainable development model, creating a high-tech city combining education and R&D, and underpinned by funding and construction of a series of solar plants in Abu Dhabi and an active renewable investment policy in various parts of the world [3]. Cross-regional electricity trade may yet prove one of the more effective ways to make renewable energy investments profitable for a growing number of investors in the MENA region. The GCC interconnector opens up the possibilities for smaller countries, such as Oman, to develop solar and wind energy projects which will change the current status of fossil-fuel dominance in the nation’s energy mix, while also permitting clean energy transfer to MENA and indeed further afield. Two of the MENA region’s largest solar plant projects, the EU-sponsored Mediterranean Solar Plant (MSP) and the GermanUS-MENA Desertec large-scale solar project, have been created in line with policy and incentive to be able to deliver profitably on an international footing [15], [16]. Prior to the steps needed towards renewable energy exchange, and potentially net export, the next five years will be crucial to Oman in determining the degree of diversification to solar and wind energy generation the country is likely to embrace. In respect of roof-top solar, the Fraunhofer study has determined the potential for a combined installation totalling 1400MW, which would constitute a sizable contribution to the Omani domestic generation requirements, not least in meeting domestic and small enterprise air-conditioning loads. This presents a challenging, and perhaps overtly optimistic, end goal. Nevertheless, if appropriate steps are taken and policies determined, a significant achievement in realising localised PV domestic requirements will represent a first for Oman in the MENA region. A detailed outline plan envisages employment opportunities ranging from 1,000 to 4,000 per annum associated with the project, including design and preparation, installation phases, and on-going post-installation maintenance. The Government of Oman is considering further developments of up to 200MW PV/CSP plant. It is envisaged that a cost-reflective tariff under long-term power purchase agreements may be used rather than by feed-in tariffs. It is hoped that such projects will receive


Eugene Coyle 2017.indd 7

07/01/2018 15:31

SDAR Journal 2017

References [1]

World Meteorological Association. WMO provisional Statement on the Status of the Global Climate in 2016. Published 14th November 2016. WMO CH-1211 Geneva 2, Switzerland.


Authority for Electricity Regulation Oman. Study of Renewable Energy Resources, Oman. May 2008. COWI and Partners Ltd. Sultanate of Oman.


IRENA International Renewable Energy Agency. Sultanate of Oman Renewables Readiness Assessment. November 2014.


Oman Electricity Transmission Company. Five-Year Annual Transmission Capability Statement (2016-2020).


Oman’s renewable energy potential – solar and wind. Norton Rose Fulbright. March 2013.


United Nations Development Programme (UNDP). Human Development Report 2010, 20th Anniversary Edition. Development of Nations: Pathways to Human Development.


Institute for Economics and Peace. Global Peace Index 2016.


BMI Research. Fitch Group Company. Oman Oil & Gas Report. 1st January 2017.


Othman, A.H. (2013). “Evolution of Thermal Desalination Processes”, Saline Water Conversion Corporation, SWDRI (Saline Water Desalination Water Institute), Riyadh, Saudi Arabia. 2013.

[10] OPWP Seven Year Statement 2016-2022. Oman Power & Water Procurement Company. Ruwi, Muscat, Oman. [11] Gulf Cooperation Council Interconnection Authority GCCIA. The Power of Six: a super grid in the Gulf. Ahmed Ali Al Ebrahim, John O’Hanlon, Richard Thomas. [12] Worley Parsons resources and energy. Solar Power Projects Review (SPPR). Implementation of Large Scale Solar Power Plant in Oman, April 2010.


Oman is dependent on desalination for its water supplies. Sea water is desalinated in seven large plants. Five plants are combined power and desalination, the remaining two are standalone water producing plants. Water demand is growing at approximately 8% per year. In the combined CCGT plants, heat is provided to the water production process. Coproduction is energy efficient, realizing 20% improved efficiency over standalone electricity and plant provision [9].


GCC reliance on IPPs is set to increase. Oman is seen as having taken a lead GCC efforts to unbundle the power sector by privatizing most of its generating assets, and is also considering privatizing transmission and distribution networks. APICORP Energy Research. Arab Petroleum Investments Corporation. September 2016. “GCC Power Markets: reliance on IPPs set to grow”.


Harweel is the location of Oman’s first major wind farm; 50 MW farm expected completion 2017


A Renewable Readiness Assessment (RRA) of the Sultanate of Oman has been undertaken by the international Renewable Energy Agency (IRENA), published in November 2014. In the report Foreword Mohammed Abdullah Al-Mahrouqi, Chairman of the Public Authority of Electricity and Water, informs that “the demand for energy in the Sultanate is increasing rapidly, due to a combination of rising population and strong economic growth; with annual electricity demand growth at 8-10%, reflecting the rapid expansion of industrial areas as the economy diversifies away from the oil and gas sectors”. Further, “the Government of Oman has started to examine the possible use of renewable natural resources for the production of electricity, with a view to diversifying the energy base of the Omani economy”.

Note: This paper is published in association with a study entitled “Steps towards the decarbonisation of the Omani electricity grid”, presented at Cigre Symposium Dublin, May/June 2017. Authors: Eugene Coyle, Jonathan Blackledge, Abid Ali Khan, Muhammad Arid Ashraf.

[13] Pudlik M, Raise C, Fraunhofer. Advisory Services on Renewable Energy Promotion in Oman. Roof-top Photovoltaic (PV) Incentive Programme for the Sultanate of Oman. [14] Bierman B, Treynor C, et al. “SolarPaces 2013; Performance of an Enclosed Trough EOR system in South Oman”. (SciVerse Science Direct, Energy Procedia 00 (2013). [15] Katiri, Laura L. The Oxford Institute for Energy Studies. “A Roadmap for Renewable Energy in the Middle East and North Africa”. January 2014. [16] Coyle E, Simmons R (2013). “Understanding the Global Energy Crisis”. Purdue University Press, 2013.pp. 118. [17] Gastli A, Charabi Y. (2010). “Siting of Large PV Farms in A-Batinah Region of Oman”, Proceedings of IEEE (Institute of Electrical and Electronic Engineers) International Energy Conference, 18-22 December 2010, Manama, Bahrain, pp. 548-552. [18] Al Badi, A.H. (2011), “Wind Power Potential in Oman”, International Journal of Sustainable Energy. Vol. 30, No. 2, 2011, pp. 110-118. [19] REVE Wind Energy and Electric Vehicle Magazine, October 2014. In partnership with the Spanish Wind Energy [i]

Governates of Oman include Muscat, Dhofar, Musandum, Al Sharqiyah South, Al Sharqiyah North, Al Wusta, Al Buraimi, Al Batinah South, Al Batinah North, Al Dhahirah, and al Dakhiliyah.


National Center for Statistics and Information, Sultanate of Oman. Population Clock.


PDO, the main oil and gas Exploration Company in Oman, owns and operates a dedicated power system, of 12 GW capacity. The network is interconnected to the MIS and Dhofar power network systems, forming an important link in the country’s wider electricity network.


Eugene Coyle 2017.indd 8

07/01/2018 15:31

CIBSE Ireland Region …

… just a click away CIBSE Ireland’s interactive website gives a comprehensive overview of the Institution’s aims, objectives, officers and committee members, along with details of its extensive CPD programme and technical evenings. It also includes regular news updates, and reports on inter-association activity, industry awards, participation in Government consultation bodies, and other promotional activity on behalf of the building services industry.

CIBSE Ireland is the leading organisation for information, guidance and advice on all building services related matters. Membership brings many benefits, including access to the full suite of CIBSE publications available online via the knowledge portal. For more information on how to become a member, or to progress to a higher grade of membership, log on now. New CIBSE Web Advert.indd 1

09/01/2018 09:04

School Elec Eng 2016:Layout 1



Page 1

Institiúd Teicneolaíochta Átha Cliath Dublin Institute of Technology

School of Electrical and Electronic Engineering The School of Electrical and Electronic Engineering, Dublin Institute of Technology (SEEE), is the largest education provider in the electrical and electronic engineering space in Ireland in terms of programme diversity (apprentice to PhD), staff and student numbers. Based in Dublin city centre (Kevin Street) and established since 1887, it prides itself in providing practice-based and professionally-accredited programmes across a variety of full-time and parttime options. The School also focuses on applied research with a strong emphasis on producing useful and novel ideas to help Irish industry compete globally. SEEE research is recognised for its impact and quality, which in many cases is on a par with that of the very best groups internationally.

SEEE Programmes Level 9 (Masters) MSc in Energy Management

DT711 or DT015

ME in Sustainable Electrical Energy Systems

DT704 or DT705

MSc in Electronic and Communications Engineering

DT085 or DT086

Level 8 (Hons) BE in Electrical and Electronic Engineering


BE in Computer and Communications Engineering


BSc in Electrical Services and Energy Management

DT035, DT712 or DT018

BSc in Networking Applications and Services


Level 7 BEngTech in Electronic and Communications Electrical Services Engineering Engineering


BEngTech in Electrical and Control Engineering


Level 7 in Electrical Services Engineering BEngTech BE in Networking Technologies BTech


For further information on the school contact: School of Electrical and Electronic Engineering, Dublin Institute of Technology, Kevin Street, Dublin 8 Tel: + 353 1 402 4617/4650/4575 Email:


Enhancing Thermal Mass Performance of Concrete

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

Roderic Bunn BA FRSA


Roderic Bunn 2017.indd 1

08/01/2018 09:09

SDAR Journal 2017

Abstract Good practice in lighting energy consumption in schools is regarded to be around 13 kWh/m2 per annum (CIBSE LG5, 2011). However, recent post-occupancy evaluations reveal lighting energy consumption in schools to be above 30kWh/m2 p.a., despite the use of energy efficient lamps, switching based on infrared presence/absence detection, and digital controls for daylight-linked dimming. To identify

Keywords Schools, Energy Lighting, DALI, Soft Landings, CIBSE TM22, LENI. Glossary DALI:

Digitally Addressable Lighting Interface


Lighting Energy Numeric Indicator


The unit of illuminance and luminous emittance,

causes of excess energy consumption for lighting, this study undertook detailed post-occupancy field measurements of the lighting consumption of two recently-completed K schools – a small primary and a large secondary – equipped with digitally-addressable lighting interface (DALI) systems. Instrumentation of individual light fittings was carried out to obtain an accurate understanding of their switching

measuring luminous flux per unit area. PIR:

Passive infrared



Soft Landings: Post-handover professional aftercare and fine-tuning TM22:

CIBSE Technical Memorandum 22: Energy Assessment and Reporting Methodology

and dimming characteristics. Results were compared with estimates of kilowatt hours per square metre per year (the Lighting Energy Numeric Indicator), calculated using the spreadsheet provided to support the European Standard that defines LENI, and against estimates of disaggregated whole-building energy consumption using the CIBSE energy assessment tool TM22. The post-occupancy evaluations uncovered excessive lighting consumption in classrooms and circulation area lighting, issues with DALI system installation and commissioning, and problems with the usability of lighting controls. Allied shortcomings included dysfunctional energy metering, lack of system fine-tuning after handover, and inaccuracies with as-built records. Methodological shortcomings were identified with the industry-standard methods of assessing lighting consumption. Recommendations are given on ways to mitigate excessive lighting energy consumption and to improve the predictive power of the current energy assessment methods.


Roderic Bunn 2017.indd 2

08/01/2018 09:09

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

1. Introduction 1.1 Introduction Literature and POE review Excessive energy consumption in UK schools is of national concern. In 2008 the schools sector was estimated to account for 10% of UK non-domestic electrical energy consumption[1], with the portion for electric lighting estimated at 8%[2]. Although fossil-fuel consumption has progressively fallen, electricity use in schools has risen. In 2009, a report by the former Department for Schools, Children and Families reported that the proportion of total national energy consumption attributable to schools had risen to 15%[3]. Recent trends in lighting guidance have focused on delivering levels of lighting conducive to visual function while maintaining energy efficiency [4]. However, problems with classroom daylighting persist, such as poor integration of glare control devices with window design, exacerbated on south elevations by the lack of external solar protection. The lack of external solar shading for classrooms on south-facing elevations leads to ad hoc glare control (Figure 1), while

Figure 1: No external shading on south-facing classrooms.

Table 1: A database of Schools for which lighting energy consumption is known School type Opened

Treated floor area in m2


Display energy certificate (in 2016)

Lighting kWh/m2 per annum (reported)


Sept 2010



C (64)



Nov 2010



B (45)



May 2010



E (102)


School Sept 2015 P (primary)









C (70)



Sept 2009



C (73)


March 2010 1990


C (68) est.


Primary Primary

Nov 2011



E (115)

14 - 26

Sixth Form Sept 2010





Secondary June 2009



C (74)


Secondary/ Sept 2008 academy






June 2009 10,172


E (108)

26.1 (from 32.5)


Sept 2008 10,490




Secondary/ Sept 2003 10,627 academy



37.3 (total)

Secondary Sept 2003 10,529 academy



70.3 (total)

Secondary/ June 2006 13,000 academy



14.9 (auto) 23.8 – 25.8 (manual)

School 2011 S (secondary)





Secondary April 2010 14,610




Secondary June 2009 16,185



3.3 Est.





Aug 2012 16,900

that the use of such lighting controls can contribute to a significant improvement in the quality and quantity of electric lighting in schools [5]. Figure 2: Poorly executed glare control.

poor integration of glare control blinds is common, particularly with openable windows (Figure 2). Digital control of lighting has become common, specifically to the Digital Addressable Lighting Interface (DALI) protocol. DALI facilitates individual control of luminaires using signals from daylight sensors and passive infrared (PIR) sensors. Research by Govén et al found

Despite such evidence, high energy consumption is still occurring. Pegg et al found excessive consumption by systems designed to be low energy but poorly controlled in practice[6]. Other researchers have pinpointed systems complexity as a root cause of performance problems[7]. Dasgupta et al analysed 113 schools and found energy use to be on average two and half times the design estimates[8]. In 2010, an £8 million Building Performance Evaluation (BPE) research programme investigated the performance of UK domestic and non-


Roderic Bunn 2017.indd 3

08/01/2018 09:09

SDAR Journal 2017

Table 2: Lighting specification for Schools S and P. School S Room



Fitting load W

Floor area m2




2x28 W Minirad 228 T5




Default to on 24/7. Lighting isolated by breaker switches

Tridonic DALI, PIR plus manual switches Neither operable during study


2x28 W Minirad 235 T5




Absence detection with manual switches

Tridonic DALI, PIR plus manual switches. Whiteboard row on local switch


2x28 W Minirad 228 T5




Absence detection with manual switches

PIR DALI. Wall switches Whiteboard row on local switch

Willow Room

2x28 W Minirad Orias T5




Absence detection with manually switched and auto daylight dimming

Whitecroft organic DALI. Switches for local dimming and preprogrammed scene selection


1x35 W Minirad Orias T5




Absence detection with manually switched and auto daylight dimming

Whitecroft organic DALI. Switches for local dimming and preprogrammed scene selection

School P

domestic buildings. Schools represented the largest percentage (14 schools or 29% of the sample). Bunn and Burman analysed academies studied under the programme and found actual carbon dioxide emissions to be three and five times greater than the design estimates [9]. Problems with automated lighting were found, such as infrared (PIR) detection control systems causing lights to default to ‘on’, both during the day and outside school hours [10], [11]. Accurate assessment of energy use and apportionment with end uses has been complicated by failings in electricity sub-metering. Post-occupancy evaluations regularly find problems with the quality of metering, interfaces with building management systems, poor commissioning, and energy metering calibration problems [12], [13], [14]. Table 1 lists recent UK schools studied for their energy performance and reported lighting energy consumption, ranked by floor area. Most schools in Table 1 are derived from the Innovate BPE programme, along with data from other schools studied between 2006 and 2015[7], [14]. The schools are characterised by widespread reliance on automated lighting control, with sometimes little or no local manual override. Technologies such as PIR detectors and daylight sensors were sometimes too sensitive in operation and therefore energy-wasteful. The zoning of lighting control was also sometimes inappropriate to space use.

2. Research hypotheses The review of the research evidence led to the following research hypotheses: • That lighting energy consumption in larger schools is a direct function of treated floor area. Larger schools will consume more energy with lighting per square metre than smaller schools due to the agglomeration of design and installation inefficiencies in lighting over a greater multiplicity of zones. • While digital control of individual luminaires may improve the theoretical performance of lighting in classrooms, the quality of installation and system fine-tuning of the lighting controls is equally important in determining achievement of lighting and design performance targets. • That current methodologies for assessing lighting energy consumption in controlled lighting, specifically CIBSE TM22 [15] and the Lighting Energy Numeric Indicator (LENI) [16], are fundamentally sound. • That current approaches to providing manual lighting override controls are contributing to sub-optimal operation of lighting and therefore increasing wasteful energy consumption.


Roderic Bunn 2017.indd 4

08/01/2018 09:09

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

3. Research design 3.1 Case study method The research design involved the monitoring and detailed energy analysis of two recently-completed UK schools, one a large secondary (School S, completed in 2010) and the other a small primary (School P completed in 2015). Both schools used digitally-addressable lighting controls based on presence or absence detection with manual override, and with daylight dimming sensors. Details of the classroom lighting installations are shown in Table 2. The secondary school (School S) replaced a 1950s school with a concrete-framed building of 13,416 m2 over three storeys. The building comprises tapering classroom wings radiating from a central atrium. Suspended linear fluorescent luminaires were used in general teaching areas in accordance with CIBSE guidance[17]. The design proposed that the lighting fittings be manually switched in conjunction with microwave absence detection, such that the luminaires automatically switch off once movement fails to be sensed after a pre-set period. Lights in close proximity to interactive whiteboards were to be separately switched. Daylight linking aimed to ensure that the light output could be modulated with the availability of natural light. School P is an existing primary school to which has been added a two-storey 1130 m2 teaching and administrative block. All classrooms face south. First floor rooms have high-level, north-facing clerestory windows. There is no roof overhang nor external brise soleil to control solar gain on the south-facing elevations (Figure 1). Manual internal roller blinds control glare. Rows of suspended T5 fluorescent luminaires are perpendicular to the windows – two rows of single 35 W fittings in some classrooms, and three rows of twin 28 W fittings in larger classrooms. The control switches have two pre-programmed scene options and manual dimming capability. Two manual control devices are provided in each classroom – one by the door to control room lighting and another to control the luminaires nearest the whiteboard. An internal daylight sensor in each classroom controls a DALI lighting system that can dim each row of fittings. Each classroom has a hard-wired DALI control module to which the daylight sensor and manual control switches are wirelessly linked.

(with some lighting on), although by that time the school was largely empty. For the secondary school, staff also tended to arrive around 07.30 and leave by 16.30, although a minority were found to be at their desks until 17:00 and sometimes slightly later. In both schools most classroom use was observed to have ceased by 16:00, and each school’s cleaners were already active. The difference in classroom hours between the school classrooms was therefore found to be small. Three separate approaches were taken to calculate and triangulate energy consumption: building energy analysis using the research version of the CIBSE TM22 Energy Assessment Reporting Methodology[15]; lighting energy consumption to the requirements of BS EN 15193-1:2017 [18]; and instrumented readings of representative lighting fittings using on-site data loggers. 3.2 CIBSE TM22 analysis In order to identify the portion of electricity consumed by the lighting systems, whole-building electrical energy models were constructed for each school using CIBSE TM22. This spreadsheet tool enables annual electrical loads in kWh/m2 to be determined based on installed wattages multiplied by hours of operation. Operational hours are assigned via user-determined operational profiles for weekday, weekend and out-of-hours use. Usage and turn-down factors can be refined. Data was obtained from an inventory of loads gathered from site inspections, and those loads apportioned against electrical supply meter data. For School S, it became apparent that the consumption of (known) sub-meters did not add up to the electrical supply (billing) meter, nor was the building management system (BMS) set up to record submeter data. Furthermore, the college’s operation and maintenance manuals did not contain a clear electrical sub-metering schematic. This prevented identification of distributed sub-meters. The facilities manager subsequently found sub-meters in electrical services cupboards, some of which were not connected. A PV array was installed in late 2015. The lack of a PV export meter complicated the energy assessment.

The research process involved technical tours of each school and interviews with the caretakers about the technical specification of the schools and their operation (e.g. hours of use, maintenance regime, post-handover changes and upgrades, and outstanding defects). As-built drawings and operation and maintenance manuals were reviewed, and the lighting installation records were compared with the actual installation. Teachers were interviewed about their use of classrooms, the manual lighting controls, and use of glare control devices. Efforts were made to reconcile the school’s electrical submeters with the energy supply (fiscal) meters, taking into account any renewables contribution.

It was decided to identify all regulated and unregulated electrical end-uses by manual inspection. The O&M manuals were data-mined to obtain installed wattages, and as-built lighting drawings checked against the lighting installation. This was supplemented by visits to count all fixed and equipment loads systematically, room by room. By this process it was found that many classrooms were fitted with twin 28 W fittings, whereas the as-built drawings erroneously recorded many classroom luminaires as having single 49 W fittings. All loads and their wattages were aggregated zone-by-zone for teaching blocks, offices, and external systems (e.g. lighting). The data were imported into a CIBSE TM22 model, and set against operational profiles as accurately as possible.

The occupied hours for the monitored classrooms in the two schools were found to vary during the school week, but were largely comparable in the length of the teaching day. For the primary school, teachers tended to arrive early at around 07:30 and leave by 16:00. Some were found to be performing administrative tasks up to 16:45

At School P, an attempt was made to reconcile sub-meters with manual readings of the billing meter and records held by school’s BMS. However, the BMS was found to record lower values than the distribution board pulse sub-meters. Manual reconciliation for the two months to 13 May 2016 found that the sub-meters reported


Roderic Bunn 2017.indd 5

08/01/2018 09:09

SDAR Journal 2017

31% more power consumption than the billing meter. As with School S, the disparity was complicated by the lack of a photovoltaic (PV) export meter. Apportionment of electrical energy by end-uses involved a manual inventory of all electrical loads, and estimation of run times from time clocks, personal observation, and insight from the caretaker. Installed wattages were checked against as-built drawings and schedules. An annualised TM22 energy model for School P was created by extrapolating from nine months (253 days) of billing meter data and dividing by the measured treated floor area. The electrical end uses were tabulated room by room, and hours of operation assigned to each load. In this way the disaggregated energy end-uses summated to within 3% of the metered (extrapolated) annual consumption. 3.3 Lighting Energy Numeric Indicator (LENI) analysis Lighting energy consumption was calculated in accordance with BS EN 15193-1:2017[18]. This Standard describes the methods for calculation of the amount of energy used for internal lighting and provides indicators for lighting energy requirements for the purposes of regulatory certification to meet the requirements of the EU Energy Performance of Buildings Directive. BS EN 15193-1:2017 defines a method of assessing the efficiency of a lighting installation, including controls, called the Lighting Energy Numeric Indicator (LENI). A LENI Excel spreadsheet, originally developed to validate the Standard, was used to calculate the efficiency of the classroom lighting. Separate LENI spreadsheets were created for each classroom. The LENI spreadsheet requires the user to define floor area, light sources, target illuminance values, daylight contribution, hours of use, daylight factor, maintenance factors, and lighting control characteristics using data entry and options from drop-down menus. Three calculation options are available for the calculation of LENI: 1. A rough calculation; 2. A more detailed calculation based on specific light sources; 3. A thorough measurement for an actual installation. Option 2 was used in this study. 3.4 On-site data logging Battery-operated, calibrated data loggers with light-sensing capability were chosen for capturing the light output from the fittings in each classroom. Relative light levels, recorded in units of Lux, were derived from placing the loggers on top of suspended luminaires, thereby using the uplit portion of light to determine switching and dimming characteristics. Although the daylight contribution could not be disaggregated from electric light, the close proximity of the data logger sensor to energised lamps (less than 20 mm) led to luminance levels of between 4000 - 10,000 lux, effectively masking any daylight contribution. The daylight contribution picked up by the data loggers when lights were off was between 50 - 120 lux, not high enough to be confused with the operation of the lights. It was also found that electric light readings would begin at around 1300 lux. The energy calculations therefore ignored all measured values below 900 lux, as all lights would be dimmed to zero, or be off, at that level of detection.

In order to balance data resolution with manageable datasets, monitoring intervals were set at five minutes. For School S, three representative classrooms were selected for study – two in Wing A (rooms A002 and A006) known to have different electric lighting characteristics, and a science room B202. The refectory and sports hall were also monitored, primarily to refine the operational profiles in the TM22 model. For School P, two south-facing classrooms on the first floor – Willow Room and Birch Room – were selected for field monitoring. An initial monitoring period bridged a half-term holiday and thereby provided evidence for any non-occupied daytime operation of the lighting. Planned out-of-hours operation was only found at School S. Initial monitoring enabled plotting of results and analysis of interim findings, and evidence for the schools’ facilities teams to improve the operation of the lighting system settings. The monitoring process was refined following assessment of the initial data. In each school, daily operation was plotted for the occupied period of the schools (and for weekends where lighting was operating) for 20 weekdays (a school month). Likely maximum hours of classroom occupation were based upon maximum lighting utilisation per day. The monitoring and operational evidence was used to backfill and/or refine the load profiles and operating hours in the TM22 energy spread sheets. This helped improve the strength of calculation comparisons. 3.5 Field data analysis The illuminance data were imported into an Excel spreadsheet. The daily maximum illuminance measured by each data logger in lux was treated as each lamp’s maximum output, and a formula devised to convert the detected lux levels for each row of lights to a power consumption value as a proportion of the maximum load as defined by the maximum lux value, with a 30% offset assumption for dimming levels as embedded in BS EN 15193-1:2017. The equation was also devised to take into account control gear losses. In the absence of guidance in the manufacturers’ lamp data sheets, a generic value of 0.3 W/m2 for losses (i.e. while the luminaire was nominally off) was added to the consumption calculations. Power consumed for every five-minute period of measurement, with manual or daylight-dimming calculated as a fractional value, was summated for each school day. Power consumption was then divided by the (measured) treated floor area to generate an average kWh/m2 value for the monitored period. This was then factored up to a standard 40-week annual occupancy for both schools to arrive at an estimated kWh/m2 p.a. for each classroom.

4. Results 4.1 TM22 assessment Results are shown in Table 3. For School S, it was possible to apportion all (known) loads to within 3736 kWh (1%) of the value reported by the main supply meter. This led to an estimated total internal lighting energy consumption of 341,767 kWh per annum (p.a.), equating


Roderic Bunn 2017.indd 6

08/01/2018 09:09

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

Table 3: Results of all energy modeling and monitoring for School S and School P. Some data contain approximations. School S Room

Assessment period

Floor area

Estimated utilised LENI results annual hours kWh/m2 p.a.

TM22 results kWh/m2 p.a.

Monitoring kWh/m2 p.a.


18 Dec – 19 Jan




24.3 - 26.7

61.76 (80.51)*


18 Dec – 4 Feb




24.3 - 26.7



18 Dec – 19 Jan




24.3 - 26.7


Willow Room

11 April – 13 May






Birch Room

11 April – 13 May






School P


Based on 280 days per year operation. Figure in brackets assumes 365-day operation.

to somewhere between 24.3 - 26.7 kWh/m2 p.a. The school’s size (13,416 m2), complexity, and difficulties with calculating loads and apportioning hours of operation, led to a wide range of assumptions, particularly hours-run at full and part-load and overall utilisation. For example, it was found that the absence detection control worked for 10% of the circulation fittings in some areas and 85% in others. Furthermore, owing to the many forms of teaching spaces in School S and its wide range of light sources, it was not possible to strictly define classroom lighting. For the purposes of the study classroom lighting was defined as that in any bounded room where formal teaching took place. This included conventional seated tuition as well as science rooms and craft skills workshops. The estimated lighting consumption of 25.5 kWh/m2 p.a. is therefore an overall figure. As such it is comparable to the lighting data reported in Table 1.

The monitoring at School S highlighted differences in classroom utilisation. Data for Room A006 demonstrates the problems inherent in assuming consistent classroom lighting hours when digital lighting controls are used. Lighting operation after 16:30 will be caused by the cleaners. During a typical mid-January week, daily hours of lighting operation in A006 varied from 4.83 hours to 7.33 hours (Figure 4). This shows that the DALI lighting system in that particular classroom was responsive to need. The responsiveness is thought more likely a function of the classroom’s occupation profile rather than daylight availability or local switching, as there is no evidence of the light fittings exhibiting dimming characteristics.

5 On-site monitoring

Severe control problems were found in classroom A002, with permanent default to “on’” (Figure 5). The light fittings in the classroom – and other rooms adjacent – were found to be on 24 h/ day, and therefore the load could occur for up to 8760 hours p.a. depending on how often power to the lighting circuit was isolated manually at the distribution board by the caretaker (the only way they could be turned off). Inspection of the lighting control system found that the DALI control wiring for the bank of classrooms (including A006) was wired back to DALI control gear located in the local electrical cupboard, rather than each classroom possessing local DALI controllers (as at School P). Without as-built records of the wiring installation, or clearly-labelled wiring, it was not possible to determine how the installers had wired the DALI system.

A wide range of lighting energy consumption profiles at School S emerged from the monitoring of the three classrooms. Room A006 performed close to good practice, with annual consumption extrapolated from a typical month’s operation of the middle row of luminaires equating to 11.28 kWh/m2 p.a. The data from Room A006 also revealed that the front row of lights were off during the monitoring period. If this operation is typical, then only six fittings out of nine would be used regularly, bringing consumption down to 7.52 kWh/m2 p.a. The data also shows no night or weekend operation. There is therefore confidence that the lights are off during vacations, except during maintenance.

Figure 4: Data for Room A006 in School S.

For the primary school (School P), the TM22 calculations returned an annual energy consumption for internal lighting as 12.2 kWh/m2 per annum, approximately half that of School S. The annual hours of operation (40 school weeks) were 578.3 h p.a. for Birch Room and 785.8 h p.a. for Willow Room. This was used to backfill the usage factors in both the TM22 and LENI spreadsheets so that hours of operation matched within a few hours.


Roderic Bunn 2017.indd 7

08/01/2018 09:09

SDAR Journal 2017

Figure 7: South-facing Birch classroom in School P.

Figure 5: The north-facing Classroom A002 in School S.

Figure 8: Monitored data Birch Room in School P.

contractor was called in to check and re-commission the classroom lighting. Although no records were available of the adjustments (which involved the entire school block), the results of the second period of monitoring seemed to reverse the initial findings: i.e. the front row of lights in Birch Room now dimmed more than the rear row (Figure 8). Figure 6: South-facing Birch classroom in School P.

Monitoring of the front row of lights in Room B202, a science classroom, showed consistently less than half the consumption of the middle row fittings. The exact reason is unknown. It may be a consequence of a pre-set scheme in the DALI installation or the teachers using the manual dimming facility for the front row lights. The 58% increase in utilisation of lighting in B202 compared with Room A006 is reflected in the room’s estimated annual consumption of 17.45 kWh/m2 p.a. A month’s monitoring results at School P indicated, by extrapolation to annual consumption, that lighting in Willow Room consumed 7.33 kWh/m2 p.a., while Birch Room consumed 5.15 kWh/m2 p.a. Some of the gap is due to the installed lighting load of Willow Room, which was 38.9% higher. However, annual consumption in Willow Room was estimated at 42.3% higher. The difference may be slightly greater utilisation, or it may be disinclination of the teacher to control the lighting, a clue being much less frequent dimming of the whiteboard row of luminaires. Figure 6 shows the south-facing Birch classroom in School P, in a “blinds-down, lights on” operating condition, and classwork stuck on glazing behind the blinds. During the initial monitoring period it was found that the rear row of lights in Birch classroom dimmed down more than the row nearest the whiteboard (Figure 7). It was initially considered that the rear of the classroom may be better daylit, and therefore that the row is more likely to dim. Nevertheless, the local authority was informed of the counter-intuitive dimming characteristic and the lighting sub-

In Figure 7 the switching of the rear row of lights on 9 March is superimposed on the operation of the front (whiteboard) row of lights (shown shaded). The front row consumed more energy prior to the DALI fine-tuning. Lighting operation after 16:30 h is usually cleaning or caretaker maintenance. Figure 8 shows monitored data from all three rows of lights in Birch Room in School P on a relatively heavily-utilised day, and after the re-programming of the DALI settings to enable the front row of luminaires to dim. 5.1 LENI calculations Details of the classroom lighting at both schools were entered into the quick version of LENI. For School S, the LENI energy calculation for classroom A002 was 15.6% lower than the closest estimate from monitored data, even using the hours of operation from the monitoring as an input to the LENI spreadsheet. The default-to-on condition of the A002 lighting, and the failure of the DALI system to exercise control, could not be reflected by any of the control options in LENI, which presumes at least some degree of effective control. The LENI prediction for Room A006 was therefore 122.3% higher than the lowest value derived from monitoring data (48.2% if all lighting rows operated identically). The LENI value for B202 was 24.3% higher than the monitored estimate, but may be only 11.3% higher if the front row lights are not dimmed manually as presumed. The LENI calculations for School P’s classrooms returned values of 11.86 kWh/m2 p.a. for Willow Room and 10.29 kWh/m2 p.a. for Birch Room. Although there is higher incidence of dimming in Birch


Roderic Bunn 2017.indd 8

08/01/2018 09:09

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

Room and more frequent switching of the whiteboard luminaires, Birch Room has four emergency fittings compared with two in Willow Room. While a 6 W emergency charging load would be present for 8760 h/p.a., the year-round consumption could not be added within LENI as the hours of use were based on the monitored data as a single, fixed, input value. The reported LENI values could therefore be 3.05 kWh/m2 p.a. higher for Birch Room, and 1.93 kWh/m2 p.a. for Willow Room. The LENI analysis indicates that the DALI-controlled classroom lighting at School P is performing close to the CIBSE LG5 “excellent” level of 12.8 kWh/m2 p.a.

6. Discussion The research project aimed to test four hypotheses as outlined in Section 3.1. The combination of physical monitoring with energy modelling (i.e. TM22 and LENI) was found to generate new and useful insights into DALI-controlled lighting in schools. The methodology provided deeper knowledge of performance of the lighting installations, and to a greater resolution than that achieved in the Innovate UK BPE studies (Table 1). As neither School S nor School P possessed functional sub-metering systems, lighting energy consumption could not be apportioned accurately. Due to School P’s small size and simplicity of lighting installation, it was possible to construct a TM22 energy model by counting loads and their run times to get within 4000 kWh (3%) of a nine-month extrapolation of the main meter total. Closer reconciliation was not possible due to the absence of a PV export meter. For the large secondary School S (over eight times the floor area of School P), the TM22 energy model could only be constructed from laboriously counting loads. Normalised to floor area, School S had approximately double the estimated lighting energy consumption of School P.

and commissioning of the DALI installation seen at School S. Performance-critical failings were found in virtually every aspect of the lighting installation, including inaccurate as-built lighting installation records, dysfunctional energy sub-metering, non-compliant DALI programming of corridor lighting, and – in the extreme case of Room A002 in A wing – a total breakdown of the automatic switching. A failure to account for such deficiencies is not a flaw of a measurement tool, whether LENI or TM22; the failure to account for such potential performance risks lies with the user of the energy model. The results from the classrooms monitored at School S show that the DALI-controlled lighting rarely dims. Nevertheless, in classrooms B202 and A006, lights nearest the whiteboards could be off most of the occupied time, providing evidence that some DALI functionality was delivered in practice. This good performance was compromised elsewhere by lighting found to default to“on” 24 h/day, without any means by which the school could turn it off, short of manually isolating the lighting power supply. It was concluded that nothing short of a complete re-wire of the system would solve the problems affecting classroom A002, and others like it (but not monitored). At School P, absence detection ensured that all lights remained off out-of-hours and during school holidays. Both classrooms demonstrated what could be achieved from a well-installed and finetuned daylight-linked lighting system. Monitored data from Birch classroom demonstrated that lighting energy consumption could be driven down to 5.15 kWh/m2 p.a. for a 40-week school year, while estimated consumption of Willow Room was close at 7.33 kWh/m2 p.a. It is thought that School P’s results could have been even lower with better passive solar detailing, and less use of glare control blinds and classroom furniture as ad hoc shading devices.

The research found that the TM22 models for both schools had inherent weaknesses in determining lighting energy consumption at the level of individual spaces. While the operational profile function in TM22 worked reasonably well for estimating switched constant-power loads, it could not model the variable operational characteristics of an addressable lighting system unless monitored data was used as input data. TM22’s operational profiles were therefore massaged until the running hours in the model broadly matched the measurements. Shortcomings were also found with the LENI spreadsheet used for the study. While the LENI spreadsheet follows the requirements of BS EN 15193-1:2017, its drop-down menus did not enable enough refinement of the key operational variables, such as the daylighting conditions and the control factors of the actual lighting installations. As a result, the actual operating hours for the lighting at School P were lower than the values output from the LENI spreadsheet. Also, for School P, the LENI spreadsheet over-predicted the monitored energy performance of the lighting. The monitored data reflected School P’s comparatively low classroom utilisation. No Standard (nor any spreadsheet based on its requirements) can be expected to cater for the extreme shortcomings in installation

Figure 8: The manual light switch installed in classrooms at School P.


Roderic Bunn 2017.indd 9

08/01/2018 09:09

SDAR Journal 2017

Although the manual lighting override controls at School P were simple in concept, the teachers were unsure of their function and found their annotation confusing (Figure 8). The teacher in Birch Room used the dimming and switching controls to control the row of lights by the whiteboard, but not the scene-setting functions, as the teacher didn’t understand them. The teacher in Willow Room claimed to use the lighting controls at least five times per day. As the monitored data did not show regular dimming of the whiteboard row of luminaires, the teacher may only be switching lights on and off.

7 Conclusions Intensive site monitoring of lighting systems in two schools has revealed how inadequacies, with their root in poor installation, have led to operational performance shortcomings. Based on the CIBSE TM22 calculation, whereby all loads were counted and their operational hours factored, the secondary school was estimated to consume double the power for lighting compared with the primary school, taking into account hours of operation (40 weeks at quoted school occupied hours), treated floor area, the various different lighting loads, and the control problems encountered in both classroom and circulation lighting. While some of this consumption at School S will be due to extended hours of operation for facilities such as the sports hall lighting, measured lighting energy consumption of the classrooms ranged from two times to 19 times higher per square metre of electrically-lit classroom space compared with the lowest estimated consumption of 5.15 kWh/m2 p.a. in School P. Despite high overall lighting energy consumption in School S, Room A006 in School S performed close to good practice, with annual consumption of 11.28 kWh/m2 p.a. This demonstrates that the lighting specification was fundamentally viable. Unfortunately, failings in installation, commissioning, and control of both classroom and circulation lighting elsewhere in the school contributed to its poor overall performance. These issues are consistent with data from other studies shown in Table 1 [6] [10] [11]. While it has not been demonstrated that lighting energy consumption rises in direct proportion to treated floor area, it is suggested that size may matter when it comes to a construction team’s ability to maintain the quality of an installation, ensuring the adequate commissioning and setting-up of the extensive use of complex systems. Risks may grow disproportionally to the construction team’s ability to deal with them. The problem may even be greater where “plug and play” systems like DALI are thought to be low risk when, in reality, they can be prone to error in installation and setting up that leads to energy penalties. These failings were found in both schools. While scale is not an excuse for poor installation and commissioning, it may be a reason why it happens. On a large school, conventional construction management practices and resources may be unable to control the increased volume of operational performance risks that on a smaller school may be managed more successfully (and incipient problems identified and resolved earlier, and more quickly). While the major lighting problems at Schools S escaped the defects period without being resolved, at School P the research monitoring during the defects period gave an opportunity to spot performance

shortcomings with the DALI systems. These were occurring under the radar not only of the teaching staff but also the school caretaker. Once the problems were spotted, the contractor quickly returned to reset the lighting controls. This was, in effect, a fine-tuning intervention of the kind recommended by Soft Landings [19]. TM22 proved a worthy modelling tool for whole-school energy estimation, particularly in the absence of sub-metered data. The research suggests that estimates that do not take account of dimming and switching characteristics may lead to inaccuracies in a TM22 assessment. The results certainly bring into question the accuracy of TM22 lighting consumption assessments reported in Table 1, as older schools with simpler lighting systems may be relatively easier to model accurately than newer schools with digitally-controlled lighting where the control regime could be highly variable. The study also shows that while LENI is robust for describing lighting energy consumption, problems emerge when there are differences between a design intention and the as-installed installation. As with all energy-consuming systems, out-turn performance of a DALI lighting installation is dependent upon the professionalism of the project team in making sure that the anticipated quality is achieved in installation and commissioning, and that system fine-tuning takes place after handover. Designers need to be mindful of construction deficiencies when calculating LENI in design, and perform sensitivity analysis so that potential performance deficiencies are transparent in their energy calculations and predictions. The final hypothesis, that manual lighting controls are not aiding efficient operation, is partly supported. Problems at School S were deeper and more fundamental than problems created by local controls. Monitoring indicated that some teachers were able (and motivated) to turn off lights nearest the whiteboards. At School P, while one teacher was able to control the lights effectively, the teacher in the adjacent classroom was less successful. It is suggested that optimisation of electric lighting via local controls can only be significant when all other parameters have been fully satisfied: i.e. a good installation, thoroughly commissioned, with diligent customer support and system fine-tuning during initial occupation. However, if the control devices are complex and confusing, end-users may be alienated and reluctant to optimise their lighting.

Acknowledgments The author gratefully acknowledges the support of the staff of the schools that took part in this study. Declaration of conflicting interests The author(s) declare no potential conflicts of interest with respect to the research, authorship, and publication of this article. Funding The research project was completed under an Engineering Doctorate sponsored by the EPSRC with industrial support and sponsorship from BSRIA Ltd.


Roderic Bunn 2017.indd 10

08/01/2018 09:09

Key factors dictating excessive lighting energy consumption in schools: a post-occupancy analysis

References [1]

Pérez-Lombard, L., Ortiz, J., & Pout, C. A review on building energy consumption information. Energy and Buildings. 40(3), 394-398, 2008.


Sustainable Development Commission. UK Schools Carbon Footprint Scoping Study. Global Action Plan, Stockholm Environment Institute & Eco-Logica Ltd. Downloaded from


Department of Children, Schools and Families. Carbon Management Strategy for Schools: Second consultation paper. London, UK, 2009.


CIBSE. Lighting Guide 5: Lighting for Education. The Society of Light and Lighting. London, UK: CIBSE Publications, 2011. ISBN 978-1-906846-17-6.


Govén, T., Laike, T., Raynham, P., & Sansal, E. Impact of Lighting Controls on the Energy Consumption of Lighting in Schools. Vienna proceedings of 27th session of the International Commission on Illumination (CIE). Sun City. South Africa, 2011.


Pegg, I. M., Cripps, A., & Kolokotroni, M. Post-Occupancy Performance of Five Low-Energy Schools in the UK. ASHRAE Transactions, 113(2), 2007.


Bordass, B., Cohen, R., & Field, J. Energy performance of non-domestic buildings: Closing the credibility gap. Building Performance Congress, Frankfurt, 2004.


Dasgupta, A., Prodromou, A., & Mumovic, D. Operational Versus Designed Performance of Low Carbon Schools in England: Bridging a Credibility Gap. HVAC&R Research, 18(1-2), 37-50, 2012.


Bunn, R., & Burman, E. (2015). S-Curves to Model and Visualise the Performance Gap – first steps to a practical tool. Peer-reviewed paper for the CIBSE Technical Symposium, London, UK 16-17 April 2015.

[10] Kimpian, J., Chisholm, S., & Burman, E. BPE report 450004. Final Report for Building Performance Evaluations on Two New Build Schools: Brine Leas Sixth Form and Loxford Secondary School. Downloaded from https://building, 2013. [11 Kimpian, J., Chisholm, S., & Burman, E. BPE report 450008. Final Report for Building Performance Evaluations on three academies: Petchey Academy, Stockport Academy, Pennywell Academy. Downloaded from https://building, 2013. [12] AECOM. BPE report 450026. Estover Community College. https://building 2014. [13] Carbon Trust. Closing the Gap – Lessons learned on realising the potential of low carbon building design. CTG047, 2011. Available from [14] Palmer J., & Armitage P. Early Findings from Non-Domestic Projects. Innovate UK Building Performance Evaluation Programme, 2014. Downloaded from [15] CIBSE. Technical Memorandum 22: Energy Assessment and Reporting Methodology. Chartered Institution of Building Services Engineers. (Unpublished research version developed for the Innovate UK Building Performance Evaluation programme, 2013). [16] H M Government. Non-Domestic Building Services Compliance Guide, 2013. On-line version accessed at http://webarchive.nationalarchives. br/non_domestic_building_services_compliance_guide.pdf. [17] CIBSE Technical Memorandum 57: Integrated School Design. London, UK: CIBSE Publications, 2015. ISBN 978-1-906846-52-7. [18] BS EN 15193-1:2017. Energy performance of buildings. Energy requirements for lighting. BSI. London. ISBN: 9780580848919. [19] Way, M., Bordass, W., Leaman, A., & Bunn R. The Soft Landings Framework. BSRIA, 2014. ISBN 978-0-86022-730-4.


Roderic Bunn 2017.indd 11

08/01/2018 09:09

Building your business requires trusted partners Today, more than ever, good business is about mutuallybeneficial and well-balanced trading partnerships. Creating, sustaining and growing such partnerships is a demanding process that, in addition to the delivery of quality products and services, requires informed communication. Existing and potential clients need to know about, and fully understand, what you provide. Building Services News is the means by which to do that. We are the partner that bridges that communications gap and helps you cement the partnerships that underpin your business.

Building Services News delivers results

Visit our website: Find us on Facebook

BSNews House Advert.indd 1

08/01/2018 09:16

Enhancing Thermal Mass Performance of Concrete

An Examination of a new interior lighting design methodology using mean room surface exitance

Kevin Kelly,


Antonello Durante,


Antonella Durante 2017.indd 1

08/01/2018 09:14

SDAR Journal 2017

Abstract This paper disseminates both new and previously-published findings to show how a whole new lighting design system can be easily implemented, whereby interior lighting is designed for appearance rather than visual performance alone. This paper presents the findings of multiple PhD research undertaken in the Dublin Institute of Technology that started in 2011 and continues. This paper is presented for a building services engineering audience and emphasises why there is a need for change, what it is that is proposed, the implications for existing practice, the benefits of the new design methodology, and the challenges remaining before it can be fully adopted in practice. Evidence is provided in this paper that MRSE is a better metric than horizontal illuminance in measuring people’s perceived adequacy of illumination in a room. Proof of concept is evidenced with respect to ensuring software can be easily developed for design using MRSE and in measuring MRSE easily in installations using HDR imaging. Typical values of MRSE in existing installations are presented.

Keywords New interior lighting design methodology, MRSE. Glossary MRSE – Mean Room Surface Exitance IH – llumination Hierarchy TAIR – Target Ambient Iiluminance Ratio CIBSE – Chartered Institution of Building Services Engineers SLL – Society of Light and Lighting Lm/m2 – Lumen/square meter Cd/m2 – Candela/ square meter Uo – Uniformity HDRi – High dynamic range imaging

1. Introduction For nearly 100 years interior lighting has been designed in workplaces to enhance performance. Illuminance levels were designed for a working plane. In offices, this was mainly an imaginary horizontal plane taking in the entire area of a room at desk level. For many decades this was a valid, reliable and easily-understood methodology, hence its longevity. This paper explains why there is a need to change existing lighting design practice from one using horizontal illuminance as the main design metric to one using a whole new methodology with new metrics called Mean Room Surface Exitance (MRSE) and Target Ambient Illumination Ratio (TAIR). MRSE is a metric invented by Cuttle[1] to measure perceived adequacy of illumination (PAI) and TAIR refers to the designed illumination hierarchy also devised by Cuttle[1]. The implications for existing practice are explained and the potential benefits/shortcomings of the new design methodology examined, along with an analysis of the challenges remaining before it can be fully adopted in lighting practice. Modern offices and educational spaces have entirely different functions than envisaged by the researchers who originally developed the existing methodology based on horizontal illuminance. There is now widespread use of screen technology and more human interaction in modern workplaces. This, and the advent of muchimproved LED technology[2], makes a new and improved lighting design methodology appropriate for such spaces, particularly as the same consulting engineers strive imaginatively towards near zero energy buildings in other design aspects. Lighting design carried out within consultant engineering offices has changed little over many decades. Work plane illuminance Eh (usually the horizontal plane throughout the room) has remained the predominant central design metric throughout that time. The CIBSE/SLL Code for lighting[3] has been the source of information for designers in the UK and Ireland (and in many other countries) during that time. In Europe, EN 12464-1[4] applies for interior lighting, in the USA the Illuminating Engineering Society of North American (IESNA) apply similar standards and all of these look towards the International Commission on Illumination (CIE) for coordination of international standards for lighting. The Society of Light and Lighting (SLL) is now part of CIBSE but, in its earlier form, it was known as the Illumination Engineering Society and Illumination Society of Great Britain. It has been setting standards for lighting for over 100 years and the SLL Code[3] is further supported by a Lighting Handbook[5] and 14 application guides[6], all published by SLL/CIBSE. All of the standards and Codes use horizontal illuminance as its main design criterion. Indeed, this has been seen by the industry as an appropriate and pragmatic method of designing lighting up to now. However, the SLL Code[3] admits that conformance with the Code can only hope to eliminate bad lighting and ensure indifferent lighting. This allows people see things quickly and easily without visual discomfort. The focus is on the visual task and functionality of the lighting. This was appropriate at one time but a higher standard is


Antonella Durante 2017.indd 2

08/01/2018 09:14

An Examination of a new interior lighting design methodology using mean room surface exitance

Figure 1a – Open plan office, Larkin Administration Building – Buffalo NY, 1930s – and 1b – Historic office and drawing office practice.

desirable nowadays to achieve good quality lighting. People in offices up to the 1980s, such as those in the in Figure 1, may well have required 500 lux on their desk and 750 lux on their drawing boards. Their visual task was entirely desk-based and visually challenging, especially if reading poor quality carbon copies and blueprints. A typical engineer, designing office lighting or classroom lighting, will use the Code[3] and Guides[6] to focus on the required horizontal illuminance and ensure that the lighting selection does not cause excessive glare, while still providing acceptable colour performance. S/he will use the lamp with optimum performance, mainly LED nowadays, and give some consideration to background illuminance or luminance, and maybe even cylindrical illuminance. However, discussions held with working engineers by the authors suggests that such consideration is not always given. So, what then is good quality lighting? According to the SLL Code[3], good lighting allows you see things quickly and easily without visual discomfort, but also serves to raise the human spirit. Up to now this latter higher ambition has largely been left to dedicated lighting designers implementing imaginative and creative designs. In Figure 2, the students would have high illuminance on their desks but there is no emphasis on the speaker or on the white board. The screen is self-illuminated, but dimming of main lighting or at least switching off lights at the top of the room is required to create focus and acceptable contrast. The students themselves may be using laptops, tablets and/or phones in which ceiling lights may be reflected, screens thus causing disability glare. Working and living environments are changing and building user demands for higher levels of comfort are increasing. So, modern work practice is different from previous practice and, in addition to considerations around self-illuminated screens, human interaction is more prevalent. Figures 3a and 3b show modern office

Figure 2a and 2b - Typical classroom using existing methods.

Figure 3a and 3b – Modern office environments.

environments. Staff are focused on self-illuminated screens in a welllit room where human engagement and interaction require cross vectors of light to provide good modelling and to enable people see each other’s reactions as they interact with one another. Reading is typically from self-illuminated tablets, phones or laptops. Even if reading from paper is required, it will not require 500 lux because it will not be for prolonged periods and will probably be from goodquality laser-printed material, (see section 2.4 and Figure 5.) Because of the changing environment and changing needs of users, Cuttle argues that a new design methodology is now appropriate[7]. This new method can be achieved by consultant engineers using reasonably standard techniques and software for all but the most demanding and high-end projects. In other words, the aim is to raise the standard of office and classroom lighting to good quality lighting, rather than the indifferent quality lighting now accepted as the norm. A new methodology, invented by Cuttle[8], can make this very achievable. It is proposed we move from designing lighting purely for visual needs to providing lighting that contributes more positively to people’s comfort and appreciation of the spaces they work in and inhabit. This means working towards designing lighting for appearance and spatial or surrounding brightness, and then focusing on visual needs, rather than designing lighting for functionality and vision only. The remainder of this paper will explain what is proposed, examine the implications for existing practice, evaluate the benefits of the new design methodology, and identify the challenges remaining before it can be fully adopted.

2. Literature Review 2.1 Visual Perception and Appearance Cuttle[8] has suggested that the profession should design interior lighting for appearance using new criteria that would relate to the visual experience of the room occupants. The premise of Cuttle’s idea is: “The key to lighting design is the skill to visualise the distribution of light within the volume of a space in terms of how it affects people’s perceptions of the space and the objects (including the people) within it. The aim is not to produce lighting that will be noticed, but rather, to provide an envisioned balance of brightness that sets the appearance of individual objects into


Antonella Durante 2017.indd 3

08/01/2018 09:14

SDAR Journal 2017

an overall design concept. This is different from current notions of ‘good lighting practice’, which aim to provide for visibility, whereby ‘visual tasks’ may be performed efficiently and without promoting fatigue or discomfort”. Cuttle [8] So, lighting design should not just be about providing lighting to make things visible; rather, it should emphasise the overall perception of the lit space. This is radical as he effectively urges the profession to move from indifferent design relying only on existing codes and guides, to good quality design that lifts the spirit of people using the space. Of course consultant engineering offices must adhere to good practice and follow established codes and guidelines, so any change must involve the legislators and the authors and editors of codes and guides. In essence,Cuttle[9] suggests two metrics to support this new methodology: 1. Mean Room Surface Exitance – the hypothesis being that MRSE can provide a more reliable metric to measure perceived adequacy of illumination than horizontal work plane illuminance; 2. Target Ambient illuminance Ratio can allow the designer achieve an Illumination Hierarchy in a room that can help improve quality. TAIR is basically considered as a ratio of illumination at a point of emphasis to the general illumination. This is effectively devising illumination hierarchies to highlight visual significance of the space and its contents. The co-author of the SLL Code, Professor Peter Boyce [10], argued that evidence would be needed to show that MRSE and TAIR lead to more satisfactory lighting and that, if research can provide positive conclusions, then this should become more widely used. Indeed, he suggests it may be one of the few ways with the potential to offer a quantum leap in light quality. “At the moment, the worth of mean room surface exitance and target/ambient illumination ratio as metrics for determining desirable light distributions are matters of belief rather than proof. What is required is some experimental evidence that mean room surface exitance is related to peoples’ perception of the amount of light in a space and that that, in turn, is more closely linked to their satisfaction with the lighting than illuminance on the horizontal working plane”. Boyce & Smet [10] Cuttle [1] argued that MRSE specified-standards would permit a wider range of solutions, particularly as uniformity would not be a criterion. He also suggested that this would allow the integration of lighting and architectural design. He maintained that the engineering-based notion perpetrated by current standards is that illumination uniformity, measured on the horizontal working plane, is a fundamental metric of lighting quality but that this was anathema to lighting designers. He argued for the integration of engineering and design by the lighting profession so that both groups could strive for lighting that is perceived by users to be of good quality.

Figure 4 – Two new metrics.

then, and are incorporated into the method that Cuttle is advocating: 1. Ambient Light (shadow-less general illumination) which is often now referred to as spatial brightness, (Cuttle refers to this as surrounding brightness); 2. Focal Glow or Highlight (separating the important from the unimportant); 3. Sharp Detail or Play of Brilliants: this excites the optic nerve and stimulates the spirit. Cuttle [9] is effectively suggesting that lighting should be designed to bring out flow and sharpness as a part of standard procedure adopted by engineering consultant practices that begins with surrounding brightness, so as to contribute to better quality lighting in all installations … in other words, to enable such lighting to raise the spirit. 2.3 Perceived Adequacy of Illumination(PAI), Mean Room Surface Exitance (MRSE) and Illumination Hierarchy(IH), Target Ambient Illumination Ratio(TAIR) PAI/MRSE is concerned with providing adequate quantities of reflected flux, i.e., adequate ambient light. The IH criterion focuses on how lighting flows and is distributed to create a pattern of illumination brightness, i.e. to provide the focal glow and detail. This is intended to direct attention to functional activities or create artistic effects. The designer will select target surfaces and designate values of TAIR based on the desired level of illumination difference required. For example, in Figure 2 the speaker and screen should be at a higher illumination than the rest of the room. Their target illuminations might be a ratio of say 3:1, giving them a distinct appearance compared to the mean brightness level in the room.

2.2 Integration of Lighting and Architecture

Cuttle [1] argues that we need to deal with peoples’ perceptions of the space, set luminous hierarchies related to the visual significance of the different scenes, and we need to do this efficiently from a design perspective. Seeing is objective, and illuminance and luminance can both be measured with instruments. Perception on the other hand is subjective and this poses a big problem. How do you measure perception? How is PAI to be measured?

Integration of lighting and architecture was first addressed by Richard Kelly in the early 1950s in the United States. Kelly [11] referred to three elements of light that have as much application today as they did

To do this Cuttle [1] invented a new metric called Mean Room Surface Exitance (MRSE) that could be measured and used as part of these new design procedures. MRSE depends on room reflectances and


Antonella Durante 2017.indd 4

08/01/2018 09:14

An Examination of a new interior lighting design methodology using mean room surface exitance

reflectances of furniture and decoration, and this measure integrates the engineering of lighting with the architecture and interior design. This metric was tested as part of PhD research in DIT completed by Duff in late 2015 [12]. The second metric TAIR used to establish Illumination Hierarchy is being tested as part of current PhD research in DIT. Figure 4 shows MRSE as the proposed metric for PAI and TAIR as the proposed metric for Illumination Hierarchy. So, we now have two new concepts measured by two new metrics. 2.4 Energy and Iiluminance levels With regard to pressure on energy use, Cuttle[1] has also challenged the illuminance values specified in codes and standards. In Figure 5, Cuttle showed that a reading task of 12-point type on white paper required just 20 lux to provide for a high level of visual performance. For reading, with font size 6, illuminance would need to exceed 100 lux he concluded. However, even this value of 100 lux falls far short of the illuminance levels currently specified by EN12461-1 and the SLL Code [1] for Lighting, and those specified by CIE and IESNA for applications where reading tasks are prevalent. Cuttle[6] concluded that the levels of illuminance specified by standards, which typically fall within the range 300 to 500 lux, are higher than are necessary for visual performance but yet may still be insufficient for PAI. This is something that legislators need to be made aware of in relation to the creation of near zero energy buildings, or at least significantly reducing energy in them and hence CO2 emissions. It will be shown later in this paper that increasing horizontal illuminance does not necessarily contribute to an increased sense of adequacy by building users. It is also apparent from Figure 5 that existing specified levels of illuminance may be too high and it is not clear they are based on any scientific evidence. There is the likelihood, however, that buildings illuminated to minimum levels of illumination indicated by the above, would be rather gloomy. However, the kernel of Cuttle’s ideas are to focus on surrounding brightness levels of buildings and then deal with illuminance on working planes afterwards. Providing sufficient surrounding brightness by dumping more lumens onto a working

Figure 5 – As applied by Cuttle, the task illuminance required to provide for relative visual performance for a range of reading tasks [9]. The reader is a normal-sighted 25-year-old with a viewing distance of 350mm. The reading matter is black print, ranging from 6 to 14 point size, on three types of paper: light (reflectance (ȡ = 0.9); medium (ȡ = 0.6); and dark (ȡ = 0.3). Reproduced from Cuttle[1]

Figure 6 – 27 Light scenes presented to 26 participant.

plane is inherently wrong and energy inefficient, according to Cuttle [9]. Indeed, if the engineer selected luminaires that focused light onto the working plane with the intention of improving efficiency then this is likely to have a negative impact on surrounding brightness. This same engineer may even reject indirect lighting systems with the not illogical view (based on existing standards and practice) that they are inherently inefficient. Research undertaken in DIT suggests otherwise [12],[17].

3. Duff Research 3.1 Initial Research Questions (RQs) with first PhD study by Duff [13] 1. What is the relationship between PAI and spatial (surrounding) brightness? 2. What is the relationship between horizontal illuminance and PAI? 3. What is the relationship between MRSE and PAI? 4. Can MRSE be calculated through lighting design software? 5. Can MRSE be easily measured in the field? 3.2 Summary of research findings A small test office space in DIT was used under controlled conditions by Duff [12] who examined 27 light scenes as indicated in Figure 8, and surveyed 26 volunteers aged between 18 and 25, with none requiring corrective eyewear. The study examined subjective response to spatial brightness and PAI.

Figure 7 – Spatial (surrounding) brightness and PAI.


Antonella Durante 2017.indd 5

08/01/2018 09:14

SDAR Journal 2017

Figure 8 – Yes responses to PAI against Horizontal Illuminance.

Figure 9 – Yes responses for varying levels of MRSE against PAI.

The study used a real-world office space (approx. 5m x 3m x 3m). Subjects viewed a range of light scenes. Each scene varied the reflectance of surfaces, the light distribution and the quantity of MRSE. When subjects viewed each scene, they were questioned about brightness and whether they believed the lighting was adequate or inadequate.

When data in Figure 8 is compared with that in Figure 9, it is clear that the proposed new metric MRSE correlates better to perceived adequacy of illumination than the traditionally-used metric horizontal illuminance (Eh ).


RQ1 – What is the relationship between spatial brightness and PAI? It was proven in this experiment under controlled conditions that a linear relationship existed between levels of spatial brightness and (PAI) Perceived Adequacy of Illumination, regardless of changes in room surface reflectance or shifts in light distribution. The scatterplot in Figure 7 summarises the data with mean spatial (surrounding) brightness rating of volunteers on the X axis. Note: The range of conditions in Figure 9 is only for relatively dim to moderate lighting conditions (MRSE levels 25 – 103 lm/m2). RQ2 – What is the relationship between horizontal illuminance and PAI? As a separate part of the same study, Duff [14] plotted the percentage of Yes responses to PAI to the traditional method of using horizontal illuminance as the main design metric and perceived adequacy of illumination. Figure 8 shows the outcome. Three outlying points strongly influenced the linear regression model, and excluding these points improves the coefficient of determination to R2 = 0.56. However, the results in Figure 8 clearly show that horizontal illuminance is not a reliable way of influencing perceived adequacy or, put another way, increasing horizontal illuminance cannot be relied on to increase perceived adequacy. Specifying high levels of horizontal illuminance may be considered wasteful of energy for this reason. RQ3 – What is the relationship between MRSE and PAI? The relationship between mean room surface exitance and perceived adequacy of illumination was investigated through studies that examined the relationship between MRSE and PAI. It was proven in this study that a simplistic linear relationship existed between level of MRSE and PAI as shown in Figure 9 [12]. The studies contained scenes with broadly uniform light distributions Regardless of light distribution or surface reflectance in this experiment, the level of MRSE had a significant influence on subjects. This study maximised at 100 lm/m2.

RQ4 – Can MRSE be calculated through lighting design software? Duff et al [15] developed and validated a radiance script* that is capable of calculating MRSE through currently-available lighting design software. He and colleagues in Arup introduced a method that utilises radiance software as a platform to calculate MRSE [15]. The authors have made the script available for download from a web link given at the end of their paper [15]. MRSE theoretically requires an infinite number of flux inter-reflections, which is not practical given the computing power available to a typical lighting consultant. The authors recommend four to five ambient bounces to be a good tradeoff between accuracy and calculation time, but this may need to change when extreme levels of surface reflectance are encountered. The accuracy of this technique is currently being tested. However, Duff argues that this script is intended only to demonstrate to software developers that the MRSE concept can be easily implemented, ready for mass future use. *Note: To run the script, users will require an OS X interface with a full suite of Radiance commands installed, along with the ability to run a range of commands in the Perl language. In general, the script works in two parts. The first applies calculation grids to each surface in the space and calculates a mean exitance value for it, the second processes the results to produce the MRSE. The scripts are available at this link:

RQ5 – Can MRSE be measured in the field? MRSE can currently be measured by recording luminance values on a grid of points on all major room surfaces. Each luminance value is then converted to exitance and the average of all values within a space is representative of the MRSE. This method is slow to implement and its accuracy is limited, and influenced, by the number of grid points that are used. Almost all spaces contain large variations in brightness located over short distances and using a grid with too few points will skew results to an unknown degree. Duff et al [15] have developed a more practical alternative using High Dynamic Range imaging (HDRi). HDR imaging is a set of techniques used in photography to produce a wider dynamic range of luminosity than is typically possible using standard digital imaging or photography techniques. Essentially, HDR imaging uses multiple


Antonella Durante 2017.indd 6

08/01/2018 09:14

An Examination of a new interior lighting design methodology using mean room surface exitance

Figure 12A and 12B –Standard HDR capture and modified image with direct flux removed [15].

exposures of the same scene to produce images that better represent the perceived luminous environment. At present, this can be applied to produce luminance-calibrated images of the lit environment as developed previously by Mardaljevic et al [16]. This procedure has been adapted by the authors to calculate the indirect flux incident on the camera lens. The intention is that multiple views of a space from various angles are captured, with the mean of the values of indirect luminous flux being equivalent to the MRSE [15]. The accuracy of this technique is also currently being tested but Duff et al [15] again emphasise that this procedure is intended only to serve as proof of concept.

6. Ongoing Research •

Further validation is required, and is proceeding, into various aspects of the work to date. Standardisation of measurement procedures for complex areas is ongoing;

MRSE levels measurement in actual offices and educational spaces is ongoing;

The tipping point for perceived adequate MRSE level in an office installation will be evaluated to establish a full MRSE scale from very dim to very bright for different applications;

Ongoing and new research into Illumination Hierarchy (IH) and Target Ambient Illuminance Ratio (TAIR).

7. Discussion and conclusion Research** undertaken in the Dublin Institute of Technology (DIT) [12] and illustrated in Figure 8 and Figure 9 shows that MRSE is a better indicator of illumination adequacy than horizontal illuminance. The changing level of MRSE within a certain range (25 to 100 lm/m2) had a significant influence on subjects’ perception of lighting adequacy, whereas horizontal illuminance proved not to be a reliable way of influencing perceived adequacy of lighting in the tests undertaken. In defence of horizontal illuminance, there are other metrics which can be used in combination with it to improve quality. Indeed, it has survived for the best part of a century because it was an easy-to-use

and reliable system. But times have changed, user needs are different and LED technology offers new opportunities for a more flexible approach. Apart from the changing nature of work with self-illuminated screens and more human interaction, there is also demand for lower energy use and better quality installations. Intuitively we knew that dumping more lumens onto a working plane in order to increase perceived adequacy was wrong, even before it was proven by Duff that MRSE is a superior metric in this respect. So, Duff’s finding are not unexpected for lighting designers. Many of them were already designing lighting schemes in the way suggested by Cuttle. However, what he has proposed are easy-to-apply metrics that can be adopted by all. In order to implement new practice, consultant engineering practices will need to be assured that design software can be made available and that such lighting schemes can easily be evaluated reliably. Duff [12,15] has also shown proof of concept in this regard, i.e. that software can be developed using the script he has made available and that MRSE can be evaluated or measured using HDR imaging. These findings to date have addressed the substantive challenges set by the industry before MRSE could be seriously considered for adoption in the codes and standards. It has not yet been proven that (TAIR) is similarly so. This research is ongoing and IH and TAIR will be further investigated, along with ongoing validation and investigation of MRSE. The energy implications of using MRSE/TAIR have still to be addressed but these authors would argue that adopting MRSE/TAIR is justified on quality grounds alone. MRSE/TAIR will now offer a wider range of solutions as uniformity will no longer be a criterion with this new design methodology. The adoption of MRSE and TAIR as new metrics in interior lighting design can only be successful if there is willingness by the industry to collaborate and engage in this experimental work by adopting this new design practice in selected applications, in other words, lighting designers and consultants willing to implement MRSE/TAIR in real world projects. Changing technology and changing user needs requires a new design methodology. It is a paradigm shift … a whole new way of doing things. MRSE/TAIR is offered as an alternative design methodology to the existing system and should not, in these authors’ views, be used as a bolt-on addition to existing practice In DIT the MRSE/TAIR concept is being implemented in selected areas of existing buildings as retrofit and in selected areas of the new


Antonella Durante 2017.indd 7

08/01/2018 09:14

SDAR Journal 2017

campus buildings presently under construction. Evaluation of these installations will form part of future research. **Note: More detailed evidence of these findings is also available through Lighting Research & Technology – this is free to download to CIBSE members. Use referenced papers or simply put Duff into search on front page of LR&T website: lighting,-research-and-technology-(lr-t).

References [1]

Cuttle C. A New Direction for General Lighting Practice (inc. discussion). Lighting Research & Technology, 2013; 45(1): 22-39. (Awarded the Leon Gaster Award, 2013) doi: 10.1177/1477153512469201


Tulla A. Editorial Newsletter. The Society of Light and Lighting Jan/Feb, 2008; 1(1).


SLL (2012) Code for Lighting, published by the Society of Light & Lighting which is part of the Chartered Institution of Building Services Engineers, London.


European Committee for Standardization, Light and lighting – lighting of work places – Part 1: indoor work places CSN EN 12464-1, 2011, Brussels; CEN.


Society of Light and Lighting (2009) The SLL Lighting Handbook, London; CIBSE.


SLL Lighting Guides 1 to 14 published by Chartered Institution of Building Services Engineers, London.


Cuttle C. (2015) Overcoming a Divided Profession. Lighting Research & Technology, 2015 Opinion Piece 47(3): 258.


Cuttle C. (2010) Towards the Third Stage of the Lighting Profession. Lighting Research & Technology, 42(1): 73-93..


Cuttle C. (2015) Lighting Design, a Perception Based Approach; Routledge UK & NY.

Acknowledgements The lighting research group in DIT comprises the authors, Dr James Duff and Dr Kit Cuttle. This paper draws from their work and could not have been written without them.

[10] Boyce P.R. & Smet K.A.G. (2014) LRT Symposium, Better metrics for better lighting – a summary. Lighting Research & Technology 2014 Vol. 46: 619-636. [11] Kelly, R (1952) Lighting as an Integral part of Architecture. College Art Journal, 12(1): 24-30. doi: 10.2307/773361 [12] Duff, J. (2015) On a new Method for Interior Lighting Design, PhD dissertation, Dublin Institute of Technology. [13] Duff J, Kelly K, Cuttle C. (2017) Perceived adequacy of illumination, spatial brightness, horizontal illuminance and mean room surface exitance in a small office. Lighting Research and Technology; 49(2): 133-146. doi:1477153515599189. [14] Duff J, Kelly K, Cuttle C. (2017) Spatial brightness, horizontal illuminance and mean room surface exitance in a lighting booth. Lighting Research and Technology; 49(1): 5-15. doi: 1477153515597733 [15] Duff J, Antonutto M and Torres S (2016) On the calculation and measurement of mean room surface exitance; Lighting Research & Technology. 2016; Vol. 48: 384–388. [16] Mardaljevic, J. Painter, B. Andersen, M. (2019) Transmission illuminance proxy HDR imaging: A new technique to quantify luminous flux. Lighting Research and Technology; 41:27–49.. [17] Cuttle, C. (2017) Development and Evaluation of a New Interior Lighting Design Methodology. PhD dissertation, Dublin Institute of Technology.


Antonella Durante 2017.indd 8

08/01/2018 09:14

Research Bank of Building Services Engineering The history of building services engineering in Ireland dates back to when our ancestors first began to research and devise engineering solutions to enhance their way of living. Archeological finds and studies have documented these down through the ages but, in respect of building services engineering, there is no single record dating back to then. However, there is a continuous record of all things relating to building services engineering in Ireland from April 1961 onwards, the year Building Services News was first published. Originally known as the Irish Heating & Plumbing Engineer, the journal has been in continuous publication since then and is now recognised as Irelandâ&#x20AC;&#x2122;s only dedicated building services journal. As such, Building Services News represents an invaluable treasure trove of building services engineering data and trends dating back over a continuous 55-year period. As a research data bank it is unique. That engineering research resource is now freely available for all to access as every single copy of Building Services News â&#x20AC;&#x201C; from April 1961 to the present day â&#x20AC;&#x201C; is currently being uploaded to the DIT Arrow site.

Log into

Find us on Facebook

Visit our website:

Untitled-1 1

17/01/2018 08:03

SDAR Journal back-catalogue at your finger tips The SDAR Journal archive goes back over six previous publications, each one of which includes a wealth of evidence-based research data on a diverse range of building services topics. This treasure trove of highly-informative papers can be accessed freely, and directly, at

t 1

09/09/ 2011


Page 2

Sustai n Engin able ee Design ring

Institutional Repositories (IRs) bring together all of a universityâ&#x20AC;&#x2122;s research under one umbrella, the objective being to preserve the information and to make it available to all interested parties.

The SD AR* Journ al Septe mber Issue 2011 1 The jo urnal of Applie in Inno d Rese vative arch Engine Built En ering of vironm the ent

Sustai na Design ble & Applie d Resear ch

in Engi


Issue 6

g of th r 2016 e Built be Environ Decem m


al Journ

search lied Re nment n & App viro e Desig the Built En bl na Sustai g and neerin in Engi

Issue 7 December 2017




al in su larly journ

d publishes

design an

Sustainable Design papers.& Applied Research research and inweEngineering the Built Environment d applied

peer revie

0 16 14:2 08/11/20

scho urnal is a

Jo is DITâ&#x20AC;&#x2122;s repository service. It currently hosts over 10,000 research papers, has had total downloads of 4.6 million to date, and over one million alone in the last 12 months. The SDAR Journal Home Page on the site includes a dramatic readership guide showing real-time downloads in progress on a world map.

d 1 rnal.ind DAR Jou SDAR Promo Advert.indd 1

The SDAR Journal is a scholarly journal in sustainable design and publishes peer reviewed applied research papers

09/01/2018 08:58

BUILDING ENGINEERING MECHANICAL, ELECTRICAL & ARCHITECTURAL DESIGN What is Building Engineering? A building can be likened to a human body - the human body has a skin (preferably without leaks!) and so does a building, both using skin to regulate temperature. The body has a heart which pumps blood and heat around the body, similar to a heating system in a building; a respiratory system that takes in fresh air and exhales stale air just like an air-conditioning system and a brain that acts as a control centre for all these systems. And just like the human body, a building has a brain – the Building Engineer – whose job it is to ensure that the building is a pleasant and productive place for the people that occupy it.

DIT is an innovator in this discipline and our graduates are in high demand as we have the only Level 8 accredited Building Engineering programme in Ireland.


YOU ARE ADAPTABLE You can travel anywhere in the world with these skills working for top Irish companies or you can work for yourself.

You can study to become a building engineer in a variety of streams. You do not necessarily have to have a Leaving Cert honours maths qualification.

For more information contact: DT026 B.Eng. Building Engineering - Level 8 Brian Clare (Programme Chair) E: T: (01) 402 3973 DT005 B.Eng.Tech Building Engineering - Level 7 Chris Montague (Programme Chair) E: T: (01) 402 3833

IBC Build Eng.indd 1

YOU ARE AMBITIOUS You want high earnings and the lifestyle to match but you also recognize that money and status is nothing unless you really are making a difference in the world.

DT033 Part-time Option – Level 7


Noel O’Neill (Programme Chair) E: T: (01) 402 3909

You will be on the frontline of a new engineering revolution. You will design and power great things while reducing carbon emissions You will build a sustainable career.

Ciara Ahern (Head Of Discipline) T:(01) 4023826 Ms Miriam Daly (School Administration) E: T: (01) 402 3659

08/01/2018 10:19

DIT offers PhD opportunities in Engineering and the Built Environment - wholetime and part-time; funded, self-funded or partnership funded with companies To find out about current opportunities contact

Sdar journal 2017 web file  

SDAR Journal 2017 — a scholarly journal in sustainable design containing peer-reviewed applied research papers

Sdar journal 2017 web file  

SDAR Journal 2017 — a scholarly journal in sustainable design containing peer-reviewed applied research papers