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CIBSE Guide F - Energy Efficiency in Buildings (3rd Edition) PDF

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CIBSE Guide F Energy efficiency in buildings The Chartered Institution of Building Services Engineers 222 Balham High Road, London, SW12 9BS The rights of publication or translation are reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the prior permission of the Institution. © Third edition May 2012; The Chartered Institution of Building Services Engineers London Registered charity number 278104 ISBN 978-1-906846-22-0 This document is based on the best knowledge available at the time of publication. However no responsibility of any kind for any injury, death, loss, damage or delay however caused resulting from the use of these recommendations can be accepted by the Chartered Institution of Building Services Engineers, the authors or others involved in its publication. In adopting these recommendations for use each adopter by doing so agrees to accept full responsibility for any personal injury, death, loss, damage or delay arising out of or in connection with their use by or on behalf of such adopter irrespective of the cause or reason therefore and agrees to defend, indemnify and hold harmless the Chartered Institution of Building Services Engineers, the authors and others involved in their publication from any and all liability arising out of or in connection with such use as aforesaid and irrespective of any negligence on the part of those indemnified. Typesetting and layout by CIBSE Publications Printed in Great Britain by The Lavenham Press Ltd., Lavenham, Suffolk CO10 9RN Note from the publisher This publication is primarily intended to provide guidance to those responsible for the design, installation, commissioning, operation and maintenance of building services. It is not intended to be exhaustive or definitive and it will be necessary for users of the guidance given to exercise their own professional judgement when deciding whether to abide by or depart from it. Contents Principles of energy efficiency — 1 Introduction 1-1 1.0 Objectives and scope 1-1 1.1 Energy efficiency drivers 1-1 1.2 How to use this Guide 1-7 References 1-8 Part A: Designing the building — Energy design checklist — 2 The design process 2-1 2.0 General 2-1 2.1 Stages in the design process 2-2 2.2 The design team 2-3 2.3 The energy efficient brief 2-4 2.4 The design contract 2-5 2.5 Equipment selection 2-5 References 2-6 3 Developing a design strategy 3-1 3.0 General 3-1 3.1 Integrating fabric and services 3-1 3.2 Integrating services 3-2 3.3 Minimising requirements for services 3-3 3.4 Integrating human factors 3-6 References 3-7 Bibliography 3-8 4 Developing an energy strategy 4-1 4.0 Energy and low carbon strategy 4-1 4.1 Definition of zero carbon 4-1 4.2 Building Regulations Approved Document L2 4-1 4.3 Planning policy 4-2 4.4 Energy strategy reports in support of planning applications 4-2 4.5 Hierarchy for developing an energy strategy 4-4 4.6 Low and zero carbon technology options 4-5 4.7 Low and zero carbon technologies 4-6 4.8 Energy metering 4-14 References 4-17 5 Concept design 5-1 5.0 General 5-1 5.1 Site considerations 5-1 5.2 Built form 5-2 5.3 Services 5-17 5.4 Summary 5-18 References 5-18 Bibliography 5-19 6 Control strategies 6-1 6.0 General 6-1 6.1 Developing a strategy 6-2 6.2 Strategic control functions 6-4 6.3 Building energy management systems 6-5 6.4 Occupant controls 6-6 References 6-7 Bibliography 6-7 7 Ventilation and air conditioning design 7-1 7.0 General 7-1 7.1 Natural ventilation 7-2 7.2 Mechanical ventilation and air conditioning 7-2 7.3 Efficient air conditioning systems 7-6 7.4 Ventilation and air conditioning controls 7-11 References 7-13 Bibliography 7-14 8 Refrigeration design 8-1 8.0 General 8-1 8.1 Reducing demand for cooling 8-1 8.2 Designing energy efficient systems 8-2 8.3 Refrigeration efficiency 8-5 8.4 Primary plant 8-5 8.5 Distribution systems 8-9 8.6 Controls 8-10 References 8-13 Bibliography 8-14 9 Lighting design 9-1 9.0 General 9-1 9.1 Design objectives 9-1 9.2 Selecting luminaires 9-3 9.3 Selecting light sources 9-3 9.4 Control gear (ballasts) 9-6 9.5 Lighting controls 9-6 References 9-10 Bibliography 9-12 10 Heating and hot water design 10-1 10.0 General 10-1 10.1 Primary plant 10-1 10.2 Distribution systems 10-9 10.3 Controls 10-11 10.4 Energy consumption 10-16 10.5 Domestic heating 10-17 References 10-17 Bibliography 10-19 11 Motors and building transportation systems 11-1 11.0 General 11-1 11.1 Minimising the motor load 11-2 11.2 Motor sizing and selection 11-3 11.3 Motor drives 11-4 11.4 Controlling the motor load 11-4 11.5 Building transportation systems 11-8 References 11-10 12 Electrical power systems and office equipment 12-1 12.0 General 12-1 12.1 Large power users 12-1 12.2 Office equipment 12-2 12.3 Energy consumption 12-3 12.4 Heat gains and air conditioning 12-4 References 12-5 13 Checking the design 13-1 13.0 General 13-1 13.1 Checking internal loads and heat gains 13-1 13.2 Checking against energy targets 13-2 13.3 Checking against environmental targets 13-4 References 13-5 14 Commissioning, handover and feedback 14-1 14.0 General 14-1 14.1 On-site checks 14-1 14.2 The commissioning process 14-1 14.3 Handover and feedback 14-2 14.4 Documenting the building 14-3 14.5 Post-occupancy evaluation and feedback 14-4 References 14-5 Bibliography 14-6 Part B: Operating and upgrading the building — Why buildings fail on energy — 15 Managing the building 15-1 15.0 General 15-1 15.1 Understanding the building 15-3 15.2 Developing an energy management strategy 15-4 15.3 Management structures 15-6 15.4 Occupant involvement 15-9 References 15-10 Bibliography 15-11 16 Acquisition and refurbishment 16-1 16.0 Acquiring a new or existing building 16-1 16.1 Refurbishing existing buildings 16-1 16.2 Energy efficient refurbishment 16-2 16.3 Building Regulations and refurbishment 16-2 16.4 Levels of refurbishment 16-5 16.5 Refurbishment measures 16-6 References 16-6 17 Maintenance and energy efficiency 17-1 17.0 General 17-1 17.1 Air conditioning inspections 17-1 17.2 Planning maintenance 17-1 17.3 Maintenance contracts 17-3 17.4 Monitoring maintenance 17-3 17.5 Checklist for maintenance and energy efficiency 17-4 References 17-4 Bibliography 17-4 Appendix 17.A1: Checklist for energy related maintenance issues 17-6 18 Energy audits and surveys 18-1 18.0 General 18-1 18.1 Retrofitting energy saving measures 18-1 18.2 Developing an energy savings carbon management programme 18-2 18.3 What are energy audits and surveys? 18-2 18.4 Planning a site survey 18-4 18.5 How to carry out energy audits and surveys 18-7 18.6 Preliminary audits 18-7 18.7 Site surveys 18-9 18.8 Assessing energy saving measures 18-11 18.9 Analysis and reporting 18-13 18.10 Implementing savings 18-15 18.11 Specific energy saving measures 18-16 References 18-16 Bibliography 18-16 Appendix 18.A1: Site survey checklist 18-17 19 Benchmarking, monitoring and targeting (M&T) 19-1 19.0 General 19-1 19.1 The m&t process 19-1 19.2 Using energy data 19-2 19.3 Setting up an m&t system 19-5 19.4 Data quality 19-6 19.5 m&t analysis techniques 19-7 19.6 Benchmarking end-uses 19-10 19.7 Setting targets 19-11 19.8 Maintaining the savings 19-12 References 19-13 Bibliography 19-14 Part C: Benchmarks — 20 Energy benchmarks 20-1 20.0 General 20-1 20.1 Overall building benchmarks 20-1 20.2 Detailed component benchmarks 20-6 20.3 Detailed end-use benchmarks 20-7 References 20-16 Appendices A-1 Appendix A1: Conversion factors, fuel data and correction A-1 of meter readings Appendix A2: Using consultants and model brief A-2 Index I-1 Principles of energy efficiency The following principles have been developed from the CIBSE policy statement on energy (available via the CIBSE website), and provide a framework for engineers to put the policy into practice. Where possible, building services engineers should make every effort to follow the principles shown below. Principle Measures for implementation of principle Relevant section(s) of CIBSE Guide F Part A: Part B: Part C: Designing Operating and Benchmarks the building upgrading the building Integrated building design Design the most energy efficient buildings and services possible. 2 to 13 — 20 Provide holistic designs which are responsive to the external climate whilst still meeting the needs of the occupants. The energy efficient brief Ensure the client’s brief includes energy efficient criteria and targets 2 — 20 for all buildings, new or refurbished. Review the project in relation to these targets and criteria as the design progresses. Benchmarking Compare designs and in-use performance of buildings with 2 to 13 19 20 appropriate benchmarks to ensure that best practice energy efficiency is being achieved. The integrated design team Work with other members of the design team in order to optimise 2 — — building energy performance. Reduce demand Keep energy demand to a minimum through careful design of built 2 to 13 — — form and services using renewable energy sources, ambient energy and passive solutions. Make every effort to avoid the need for air conditioning. Design for operation Design for commissionability, maintainability and manageability 2 to 13 — — by keeping solutions simple and eliminating potential failure pathways. Optimise plant Select the most efficient plant, using certified or otherwise 7 to 12 18 — independently verified product performance data, and ensure that plant and equipment are not oversized. Use effective controls Introduce energy efficient controls which operate systems 6 to 11 18 — efficiently, safely and economically, whilst still allowing individual occupants to alter their own comfort levels, but avoiding systems defaulting to ‘on’. Ensure complete handover Ensure that building services are properly commissioned and handed 14 — — over to managers, operators and occupants. Improve operation Encourage energy efficient operation of buildings through — 15 to 19 20 management, policy, maintenance, monitoring and control. Understanding the building Provide managers, engineers, operators and occupants with suitable 14 15 — documentation to ensure they understand the design intention and how the buildings are meant to function. Monitoring and feedback Develop a strong element of feedback to improve understanding 13, 14 19 20 from previous good and bad experience related to these principles. Introduce appropriate metering to improve information and to detect faults rapidly. Build-in energy efficiency Always consider introducing energy efficient technologies 3 to 12 15–19 — throughout the design and upgrade processes but avoid unnecessary complications. Seek opportunities for improving existing buildings during operation, maintenance, alteration and refurbishment. Environmental impact Minimise adverse effects on the external environment. Minimise 3 to 12 15–19 — emissions and select environmentally friendly materials and fuels, utilising renewable sources as much as possible. An energy efficient building provides the required internal environment and services with minimum energy use in a cost effective and environmentally sensitive manner Introduction 1-1 The document promotes a holistic approach to design and operation by recognising that there is a strong interaction between the building envelope, heating and cooling systems, lighting etc. The overall design intent should always be considered before implementing individual measures. 1.1 Energy efficiency drivers The UK government has committed the UK to legally binding targets to reduce carbon emissions by 80% by 2050(1). Carbon emissions from the UK’s non-domestic buildings (comprised of commercial offices, hotels, shops, schools, hospitals, factories and other buildings), are responsible for 18% of the UK’s total(2). In 2010, total UK net emissions of carbon dioxide were provisionally estimated to be 491.7 million tonnes (Mt)(3). All building professionals have a responsibility to reduce this through the application of good practice. The key drivers for energy efficiency are: — legislation, in particular, Building Regulations Approved Documents L2A(4) and L2B(5) and the Carbon Reduction Commitment Energy Efficiency Scheme (CRC)(6) — planning policies that relate to energy often include energy efficiency as well as a target contribution from low/zero carbon technologies — reduced operating costs through lower energy use — fiscal penalties or incentives, such as the climate change levy, enhanced capital allowances and the feed-in tariff — risks to professional reputation due to poor performance; this includes Energy Performance Certificates, Display Energy Certificates, the CRC league table etc. There are also benefits from occupying an energy efficient building, which include: — an improved perception of the building when it is being sold or let 1.0 Objectives and scope This Guide shows how to improve energy performance, reduce running costs and minimise the environmental impact of buildings by: — designing energy efficient new buildings and refurbishment of existing buildings — managing and operating buildings in an energy efficient way — upgrading buildings to improve ongoing energy efficiency — enabling engineers to overcome barriers to energy efficiency in discussions with clients and other members of the design and construction team — demonstrating the value of energy efficiency to clients, developers and tenants. An energy efficient building provides the required internal environment and services with minimum energy use in a cost effective and environmentally sensitive manner. There is, therefore, no conflict between energy efficiency and comfort. Hence, energy efficiency can be combined with other aspects of sound engineering practice, as set out in other CIBSE Guides. This document is primarily targeted at building services engineers and takes a holistic approach to designing and operating buildings. The early sections will also be useful to other members of the design team including architects and surveyors. The latter sections should also be useful to other building professionals such as energy managers, facilities managers, developers, clients, property agents and occupiers. Sections of particular relevance to each reader are shown in section 1.2. This document covers opportunities for achieving energy efficiency. It complements existing guidance by CIBSE and others and refers readers to more detailed information where relevant. It does not cover process energy nor detailed design methods. Although it concentrates on non-domestic buildings, much of the information is also relevant to the domestic sector. 1 Introduction 1.0 Objectives and scope 1.1 Energy efficiency drivers 1.2 How to use this Guide Operating and upgrading the building Managing the building Acquiring/refurbishing Maintenance Upgrading energy efficiency Checking by M&T Maintaining the savings Introduction Benchmarks Designing the building The design process Design strategy Concept design Specific design Checking the design Handover Energy strategy 1-2 Energy effi ciency in buildings — the potential for improved occupant health and wellbeing as low-energy buildings often have improved levels of daylight, air quality and natural ventilation. 1.1.1 Reducing national energy use through improved staff motivation Studies (7) have shown that there is a large potential to improve the energy effi ciency of existing buildings through cost effective technologies and techniques. The Intergovernmental Panel on Climate Change (IPCC) report(8) suggests that commercial and public sector buildings could achieve an 18% reduction (14.5 MtCO2) in carbon emissions through no/low cost energy effi ciency measures (i.e. costing less than £40/tCO2). There is the potential for an additional 23% (18 MtCO2) through the application of microgeneration technologies. The breakdown of total carbon emissions by sector in the UK is shown in Figure 1.1. Typical energy breakdowns for various types of building are shown in chapter 20. Figure 1.2 shows the breakdown of CO2 emissions by end use in each sector. Carbon emissions from non-domestic buildings have remained relatively constant since 1990, often due to increased amounts of offi ce equipment, and associated air conditioning to remove internal heat gains emanating from this offi ce equipment. The current and proposed legislation and policy initiatives (see section 1.1) for energy effi ciency in new and existing buildings are intended to help to start reducing carbon emissions from this sector. 1.1.2 Environmental issues Burning fossil fuels contributes to atmospheric pollution, resulting in a wide range of damage both to the environment and public health, see CIBSE policy statement on Climate Change (http://www.cibse.org/policystatements). There is very high confi dence amongst the scientifi c community that the increase in global average temperatures since the mid-20th century is due to the increasing global warming gases from human activities(8). Improving energy effi ciency will help reduce the risk of dangerous climate change. Burning fossil fuels also results in emissions of SOx and NOx, both of which contribute to acid rain. The UK has developed a policy framework to reduce emissions. The key elements of this framework are set out below: — The Climate Change Act(1) has set legally binding targets to reduce greenhouse gas emissions by 80% by 2050, with an interim target of 34% by 2020, based on 1990 levels. — The UK government has set a target for 15% of electricity to be generated from renewables by 2020(9). — The Low Carbon Transition Plan(10) sets out how the above targets could be achieved and includes a proposed policy framework to deliver the savings. — The UK Government’s Carbon Plan(11) sets out a series of actions and commitments for delivering a low carbon economy. — The UK government has announced its aspiration that all buildings will to be ‘zero carbon’ by 2019, with earlier targets for schools and homes (2016) and public buildings (2018)(12), see section 4.1.  Domestic  Commercial and public buildings  Industrial buildings  Industrial process  Transpo Transpo T rt  Agriculture  Industrial  Retail  Hotels, inns and restaurants  Commercial offices  Schools  Further and higher education  Government estate  Sports  Public offices  Heritage and entertainment  Healthcare  Transpo Transpo T rt/communications  Miscellaneous 18 15 9 7 4 4 1 4 3 3 1 14 23 33% 22% 1% 26% 14% 4% Non-domestic buildings 18% In 2005, the UK emitted 560 MtCO2* MtCO2 (2005) * Source: Digest of UK Energy Statistics: BRE Figure 1.1 Breakdown of non-domestic buildings emissions by sector (reproduced from Building the future today(2), by permission of the Carbon Trust) Introduction 1-3 — The Energy Performance of Buildings Directive(13) has introduced higher standards of energy conservation for new and refurbished buildings and requires energy performance certifi cation for all buildings when sold or leased. In addition it will introduce regular inspections for larger air condition ing systems and advice on more effi cient boiler operation for commercial property. These requirements are addressed as follows: — The 2010 changes to Building Regulations Approved Documents L2A(4) and L2B(5), include a 25% (aggregate) reduction in CO2 emissions for non-domestic buildings. — All properties when bought, sold, built or rented need to have an energy performance certifi cate (ePc). Larger public buildings also need a display energy certifi cate (DEC). — Air conditioning inspections have to have been completed on all existing systems over 12 kW by January 2011. New systems over 12 kW installed after January 2008 must be inspected within 5 years of being put into service. The inspections must be carried out by an accredited energy assessor and must be a maximum of fi ve years apart, see section 17.1. — The UK government’s Planning Policy Statement 1(14) sets out how spatial planning should contribute to reducing emissions and stabilising climate change (mitigation), and take into account the unavoidable consequences (adaptation). It requires local authorities to develop a strategy for low/zero carbon energy generation and to develop site- specifi c targets. See section 4.3 for more information on planning policy. — The CRC Energy Effi ciency Scheme(6) is a man- datory scheme aimed at improving energy effi ciency and cutting emissions in large public and private sector organisations, see section 1.1.5. — Taxation: the Climate Change Levy was intro duced in 2001 and affects almost all non-domestic buildings. The levy is an additional cost on top of the previous price of energy. — Financial support: enhanced capital allowances (ecas) provide a tax incentive to encourage the purchase of energy effi cient technologies as defi ned on the energy effi ciency technology list (http:// www.eca.gov.uk). This covers a wide range of technologies including ‘good quality’ combined heat and power (chP), boilers, lighting, variable speed drives, refrigeration, pipework insulation and a wide range of controls. Building professionals should also consider the wider sustainability impacts of their decisions including: — reducing water use — considering the lifecycle impacts of materials and equipment — adapting buildings for climate change etc. These issues are covered in more detail in CIBSE Guide L: Sustainability (15). 1.1.3 Building Regulations Approved Document L2 The Building Regulations(16) for England and Wales impose requirements* aimed at improving the energy effi ciency of domestic and non domestic buildings. Building Regulations Approved Documents offer various means for meeting these requirements. The 2010 revision of Building Regulation Approved Document L2A(4) aims to improve the energy effi ciency standards of new buildings by 25% compared to the 2006 Source: BRE, Carbon Trust analysis End use 0% 20% 40% 60% 80% 100%  Heating  Lighting  Cooling and ventilation  Catering  Hot water  Office equipment  Other Commercial offices Schools Further and higher education Government estate Healthcare Sports Heritage and entertainment Transpo Transpo T rt/communications Public offices Miscellaneous Hotels, inns and restaurants Retail Industrial Figure 1.2 Breakdown of CO2 emissions by end use in each sector (2006) (reproduced from Building the future today(2), by permission of the Carbon Trust) * Similar guidance is available for Scotland(17) and Northern Ireland(18) 1-4 Energy efficiency in buildings edition. This is a step towards zero carbon new non- domestic buildings. Approved Document L2B(5) applies to work relating to: — the construction of extensions — a material change of use or a change in a building’s energy status — the provision or extension of a controlled fitting — the replacement or renovation of a thermal element. More details on the scope of Approved Document L2B is set out in section 16.3. The key aspects of the criteria in L2A are: (1) An ‘aggregated’ approach, which requires some buildings to achieve a greater improvement, others less, with the overall improvement across the new non-domestic building stock being 25%. This recognises that some building types can save carbon more cost effectively than others. The standards have been set such that all building types achieve their targeted improvement at similar levels of cost effectiveness. (2) Criterion 1: Achieving the target emissions rate: — The target emissions rate is based on a building of the same size and shape as the actual building, constructed to a current specification. There are three sets of spec- ifications depending on the glazing in the building or spaces in the building: one for side-lit buildings (e.g. offices), one for roof- lit buildings (e.g. some warehouses) and the third for unlit buildings (e.g. plant rooms). It is possible to comply with Building Regulations Part L 2010(16) by exactly meeting one of these current specifications. There is still the freedom to vary the specification, provided that the same overall level of CO2 emissions is achieved or bettered. — A design stage CO2 emission rate calculation is required as part of the plans submitted before construction. The builder has to carry out a preliminary calculation before construction starts and this is provided to building control, along with the specifica- tions that deliver the claimed performance. (3) Criterion 2: Limits on design flexibility: — There are limits on design flexibility for building services to ensure that they have a minimum level of energy efficiency as set out in the Non-domestic Building Services Compliance Guide(19) (referenced throughout this Guide). — Appropriate controls should be provided to enable reasonable standards of energy efficiency in use (see chapter 6 for more guidance). — Reasonable provision for energy meters should be provided to meter the various end use categories (heating, lighting etc.), renewable energy systems, and to provide automatic meter reading and data collection facilities (see section 4.8.3). — The provision of centralised switching of appliances should be considered, to allow appliances to be switched off when they are not needed. (4) Criterion 3: Limiting the effects of solar gains in summer: — A limit on the solar gain per unit area of façade is set. This limit applies to both naturally ventilated and air conditioned spaces. This will not prevent the use of highly glazed facades, but where they are proposed, it will require that good solar protection is provided. (5) Criterion 4: Quality of construction and commis- sioning: — The insulation should be reasonably continuous over the whole building envelope and the air permeability needs to be within reasonable limits. — Fixed building services have to be commis- sioned to ensure that they use no more fuel and power than is reasonable. This includes preparing a commissioning plan and carrying out air leakage testing of ductwork (see chapter 14 for more detail on com- missioning). (6) Criterion 5: Provisions for energy efficient operation of the building: — The owner of the building should be provided with sufficient information about the building to allow energy efficient operation. This includes the provision of a building log book (see section 14.4.1) 1.1.4 Energy Performance Certificates and Display Energy Certificates In England and Wales, there are two types of energy certificates: — Energy Performance Certificates (EPCs): required for all buildings when constructed, sold or rented — Display Energy Certificates (DECs): required for buildings ‘with a total useful floor area over 1000 m2 occupied by public authorities and by institutions providing public services to a large number of persons and therefore frequently visited by those persons’. There are similar requirements in Northern Ireland. Scotland has adopted a different approach, with Energy Performance Certificates (EPCs) being used for display purposes instead of DECs. EPCs present the theoretical, design energy efficiency of buildings. DECs show actual energy consumption over the course of a year, benchmarked against other similar buildings. Where buildings have both an EPC and a DEC, this provides another means of comparing design and actual energy use. Figure 1.3 shows an example of an EPC and a DEC. Introduction 1-5 The intrinsic building quality (illustrated by the EPC) has an impact on the operational performance (shown in the DEC), but does not cover all emissions. Other factors such as unregulated loads (e.g. IT equipment, plug-in appliances etc.) or building user behaviour also affect energy use and emissions, which are reflected in the DEC. 1.1.4.1 Energy Performance Certificates The EPC is a certificate that incorporates an ‘asset rating’ based on the ‘theoretical’ performance of a building as calculated using an approved method such as SBEM(20) or SAP(21). Its function is to enable like-for-like comparisons between buildings used for similar purposes and influence potential buyers’ and tenants’ decisions. The rating is calculated as the ratio of the CO2 emissions from the actual building (BER) to those from a reference building using the ‘reference emissions rate’ (NER). The reference building: — is the same size and shape as the actual building — has the same activity schedules — has a defined servicing strategy including gas heating and seasonal mixed mode cooling systems — uses natural gas as the primary fuel for heating and hot water, and electricity for lighting, cooling, fans and pumps — has CO2 emissions equivalent to the target emissions rate (TER) of a building that complies with Part L (2010) with the provisions as above. The asset rating is then represented on an arithmetic scale consisting of seven bands, labelled A to G. The EPC also displays the asset rating in context with the current Building Regulations Part L standard based upon the actual building and in comparison with a typical existing example building. 1.1.4.2 Display Energy Certificates The Display Energy Certificate (DEC) is a certificate that incorporates a numerical indicator of performance, known as the Operational Rating (OR), which is the ratio of actual measured energy use of the building over a year to a benchmark figure for buildings of that type. DECs must be displayed in a prominent position and be renewed every 12 months. The certificate must be accom- panied by an advisory report which is valid for up to seven years. The certificate must be at least A3-size. The OR is calculated using approved software and is based on a complete year of measured energy data. The rating takes account of mixed uses, local heating degree-days, extended hours of use, and some special ‘separable’ energy uses. Main heating fuel: Gas Building environment: Air Conditioned Total useful floor area (m2): 2927 Building complexity (NOS level): 4 Certificate Reference Number: 1234-1234-1234-1234 Energy Performance Certificate Non-Domestic Building Less energy efficient A 0-25 B 26-50 C 51-75 D 76-100 E 101-125 F 126-150 G Over 150 More energy efficient A+ Net zero CO2 emissions This is how energy efficient the building is. 92 Benchmarks Technical information If typical of the existing stock If newly built Buildings similar to this one could have ratings as follows: Jubilee House High Street Anytown A1 2CD 58 94 This certificate shows the energy rating of this building. It indicates the energy efficiency of the building fabric and the heating, ventilation, cooling and lighting systems. The rating is compared to two benchmarks for this type of building: one appropriate for new buildings and one appropriate for existing buildings. There is more advice on how to interpret this information on the Government’s website www.communities.gov.uk/epbd. Energy Performance Asset Rating (a) (a) (a) (b) Figure 1.3 Examples of (a) an Energy Performance Certificate and (b) a Display Energy Certificate 1-6 Energy efficiency in buildings The OR is a linear scale running from 0 (true zero-carbon) to 100 (CO2 emissions at typical stock median performance levels) and beyond. This scale is grouped into increments of 25 to provide the A to G banding, so median performance lies at the D to E boundary. All buildings with emissions over 150% of the benchmark value are classed in the G band. The DEC also shows separate performance indicators and benchmarks for annual use of electricity and of fuel or heat. The DEC benchmarks, published as CIBSE TM46(22), are based on a rationalisation and considerable simplification of values taken from many sources and consultation with industry. Although the system identifies a total of 237 different building types, each is assigned to one of 29 benchmark categories, based on the building use. Benchmarks are set at the median level for each category (as far as these were known) for annual use of electricity and of fuel or heat. Mixed-use benchmarks, e.g. for a school with a swimming pool, can be built up, using the specific component benchmarks and their respective areas. ‘Separable’ energy end-uses (specific ‘process’ uses that are not included in the benchmark because they are either unusual for the benchmark category or highly variable) can be excluded from the operational rating calculation, although they remain in the carbon footprint shown on the DEC. The energy use can only be separated if it meets the criteria as set out in CIBSE TM46(22). 1.1.4.3 Energy Performance of Buildings Directive (recast) The Energy Performance of Buildings Directive (recast)(13) has reduced the threshold size for buildings that have to display energy performance certificates as follows: — From 9 July 2012 legislation, regulations and administration provisions for 500 m2 threshold must be ‘adopted and published’. — From 9 January 2013 provisions for 500 m2 threshold must be applied, i.e. must have come into force. — From 9 July 2015 the threshold is lowered to 250 m2. 1.1.5 CRC Energy Efficiency Scheme The CRC Energy Efficiency Scheme(6) (formerly known as the Carbon Reduction Commitment) is a mandatory scheme aimed at improving energy efficiency and cutting emissions in large public and private sector organisations. The scheme will promote energy efficiency by: — requiring participants to buy allowances from Government each year to cover their emissions in the previous year; this means that organisations that decrease their emissions can lower their costs under the CRC scheme — publishing an annual performance league table that ranks participants on energy efficiency performance — increasing awareness of energy use from a require- ment to report energy use and the requirement for senior management being responsible for the reporting. The ranking on the league table includes ‘early action metrics’ for the first two years of the scheme. These metrics reward participants on the percentage of their electricity and gas supplies that is covered by voluntary automatic meter readings (amrs) (see section 4.8.3) and the proportion of the organisation’s CRC emissions certified under the Carbon Trust Standard(23) or an equivalent scheme. Organisations are eligible for CRC if they (and their subsidiaries) have at least one half-hourly electricity meter (hhm) settled on the half-hourly market. Organisations that consumed more than 6000 megawatt-hours (MW·h) per year of half-hourly metered electricity during 2008 qualify for full participation and registration with the Environment Agency, which is the administrator for the scheme. For more information refer to the Department of Energy and Climate Change website (http://www.decc.gov.uk). 1.1.6 The role of building professionals Building services engineers work within an industry that has significant environmental impacts. Building services engineers are directly responsible for ensuring that buildings: — provide acceptable thermal comfort for occupants — use minimum amounts of fuel and energy — are adequately and attractively lit — provide good indoor air quality — are adaptable to climate change — are properly operated and maintained. All of these responsibilities have a direct impact on the energy performance of buildings. CIBSE has taken a leading role over the pursuit of energy efficiency in order to reduce the risk of dangerous climate change. For these reasons, all building professionals should always encourage clients, owners and operators to include energy efficiency in the brief at all stages in a building’s life whether designing, operating or upgrading. Clients and financiers should be made aware of the investment case for energy efficiency. Building professionals should help clients to develop a brief which sets out both user and client requirements and constraints, balancing these against capital costs, running costs, whole life costs and environmental objectives. Building professionals will benefit by: — helping clients to meet current and forthcoming legislative/policy targets — providing an added-value service to their clients by improving their buildings — reducing plant capital cost, particularly where mechanical cooling has been avoided or minimised — enhancing the standing of all building pro fessionals by improving occupants’ use and perception of buildings Introduction 1-7 — increasing building marketability by promoting buildings as assets in which to invest — obtaining repeat work through satisfied customers. The overall goal is ‘better buildings’ and this can often be achieved by focussing on energy efficiency. Research(24,25) has indicated that buildings that are designed and managed in an energy efficient way can be more comfortable and their staff more productive, making investment in good energy efficient design and management even more cost effective to a client organisation. 1.2 How to use this Guide 1.2.1 Structure This Guide starts by setting out an overall framework for energy efficiency within which the building professional has the freedom to design, operate or upgrade a building. The ‘principles of energy efficiency’ stated at the front of this Guide are broadly based on the CIBSE policy statement on energy (http://www.cibse.org/policystatements), and aim to help professionals put the policy into practice. The main body of this Guide is divided into three parts as shown in Figure 1.4. — Part A: Designing the building: consists of chapters 2 to 14 and deals with new buildings and major refurbishment. — Part B: Operating and upgrading the building: consists of chapters 15 to 19 and covers the manage ment and maintenance of buildings, high lighting measures that can be retrofitted in existing buildings. The reader is referred back to Part A where there is a large element of design. — Part C: Benchmarks: consists of chapter 20 and provides ‘typical’ and ‘good practice’ energy benchmarks for a wide range of buildings, components and end-uses. A thumbnail icon at the top of the first page of each chapter indicates the relationship of that chapter to the rest of the Guide. The first chapter in each part provides a strategic overview of the process being covered. The last two chapters in each part help check that the main options have been considered and that the final outcome meets expectations. The chapters of this Guide particularly relevant to readers from various professions are shown in Table 1.1. Appendix A1 gives some standard conversion factors and properties of fuels. Appendix A2 considers the role of energy consultants and provides model briefs for commissioning energy audits and surveys. Managing the building Aquisition and refurbishment Maintenance and energy efficiency Energy audits and surveys Benchmarking, monitoring and targeting Designing the building Principles of energy efficiency 15 16 17 18 19 Introduction 2 3 4 5 6 7 8 9 10 11 12 13 14 Operating and upgrading the building Part A Part B The design process Developing a design strategy Developing an energy strategy Concept design Control strategies Ventilation and air conditioning design Refrigeration design Lighting design Heating and hot water design Motors and building transportation systems Electrical power systems and office equipment Checking the design Commissioning, handover and feedback 1 20 Energy benchmarks Benchmarks Part C Figure 1.4 Structure of the Guide Table 1.1 Sections relevant to readers from various professions Reader Part Section Building services designers Designing the building 1–14 Building owners/operators Operating and upgrading 15–20 the building Energy managers/consultants Operating and upgrading 15, 18–20 the building Architects/surveyors Designing the building 1–14 Developers/financiers Designing the building 1–6, 15 1-8 Energy efficiency in buildings 1.2.2 Investing in energy efficiency Many organisations are now investing in energy efficiency to improve their overall environmental perfor mance. This usually results in an overall corporate social responsibility (csr) policy, either laid down by senior management or as a result of government initiatives in the public sector. It is recognised by these organisations that measuring and reporting environmental performance against targets can significantly enhance the corporate image, which may influence future investors. Although the policy framework is becoming stronger, in practice cost savings often drive energy efficiency. This Guide therefore concentrates on cost effective measures. Savings in operating costs will flow directly into the building user’s profits. Well-managed organisations tend to re-invest some of the savings in further energy efficiency measures. Additional investment may also be justified for environmental reasons, e.g. emissions trading. Energy efficiency measures should generally be considered in their order of economic payback, complexity and ease of application. Measures fall into three broad types: — no-cost/low-cost: requiring no investment appraisal — medium cost: requiring only a simple payback calculation — high capital cost: measures requiring detailed design and a full investment appraisal. Investment in energy efficiency should be treated on the same basis as any other financial decision, and should have no more onerous conditions placed upon it than any other investment. A variety of financial appraisal methods can be used to assess the viability of energy saving measures (see section 18.8). Assessments should always take into account the wider benefits such as improvements in comfort and the environment. This can be achieved using a life-cycle approach. Energy efficient buildings need cost no more to build than conventional buildings. The integration of the fabric and services design can present opportunities to reduce capital cost. For example, the cost of external shading can be offset by minimising or avoiding air conditioning plant. References 1 Climate Change Act 2008 Elizabeth II Chapter 27 (London: The Stationery Office) (2008) (available at http://www.legislation.gov. uk/ukpga/2008/27) (accessed June 2011) 2 Building the future today — Transforming the economic and carbon performance of the buildings we work in CTC765 (London: The Carbon Trust) (2009) (available at http://www.carbontrust.co.uk/ Publications) (accessed June 2011) 3 Department of Energy and Climate Change (DECC) Digest of United Kingdom Energy Statistics 2010 (London: The Stationery Office) (2010) (available at http://www.decc.gov.uk/en/content/ cms/statistics/publications/dukes/dukes.aspx) (accessed June 2011) 4 Conservation of fuel and power in new buildings other than dwellings The Building Regulations 2000 Approved Document L2A (London: NBS/RIBA Publications) (2010) (available at http:// www.planningportal.gov.uk/buildingregulations/approveddocu- ments/partl) (accessed June 2011) 5 Conservation of fuel and power in existing buildings other than dwellings The Building Regulations 2000 Approved Document L2B (London: NBS/RIBA Publications) (2010) (available at http://www.planningportal.gov.uk/buildingregulations/approved documents/partl) (accessed June 2011) 6 CRC Energy Efficiency Scheme (website) (London: Department of Energy and Climate Change) (2011) (http://www.decc.gov. uk/en/content/cms/emissions/crc_efficiency/crc_efficiency. aspx) (accessed June 2011) 7 Building a low-carbon economy — the UK’s contribution to tackling climate change (London: The Stationery Office) (2008) (available at http://www.theccc.org.uk/reports/building-a-low-carbon-economy) (accessed June 2011) 8 Pachauri RK and Reisinger A (Eds.) Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (Geneva, Switzerland) (2007) (available at http://www.ipcc.ch/publications_and_data/ publications_ipcc_fourth_assessment_report_synthesis_report. htm) (accessed June 2011) 9 The UK renewable energy strategy Cm. 7686 (London: (The Stationery Office) (2009) 10 The UK low carbon transition plan: national strategy for climate and energy (London: The Stationery Office) (2009) (available at http://www.decc.gov.uk/publications) (accessed June 2011) 11 Carbon Plan (website) (London: Department of Energy and Climate Change) (2011) (http://www.decc.gov.uk/en/content/cms/ tackling/carbon_plan/carbon_plan.aspx) (accessed June 2011) 12 Zero carbon for new non-domestic buildings: Consultation on policy options (London: Department for Communities and Local Government) (2009) (available at http://www.communities.gov. uk/publications/planningandbuilding/newnondomesticcon- sult) (accessed June 2011) 13 Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (recast) Official J. of the European Union L153 13–35 (18.6.2010) (available at http://eur-lex.europa.eu/JOHtml.do?uri=OJ:L:201 0:153:SOM:EN:HTML) (accessed June 2011) 14 Planning Policy Statement 1: Delivering Sustainable Development (London: The Stationery Office) (2005) (available at http:// www.communities.gov.uk/publications/planningandbuilding/ planningpolicystatement1) (accessed June 2011) 15 Sustainability CIBSE Guide L (London: Chartered Institution of Building Services Engineers) (2007) 16 The Building Regulations 2010 Statutory Instruments 2010 No 2214 (London: The Stationery Office) (2010) (available at http:// www.legislation.gov.uk/uksi/2010/2214) (accessed December 2011)

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