Defining a Fabric Energy Efficiency Standard for Zero Carbon Homes
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DEFINING A FABRIC ENERGY EFFICIENCY STANDARD FOR ZERO CARBON HOMES Task Group Recommendations November 2009 FACILITATING THE MAINSTREAM DELIVERY OF LOW AND ZERO CARBON HOMES Defining a Fabric Energy Efficiency Standard for zero carbon homes Zero Carbon Hub Acknowledgements Further copies of this report are available as a The Zero Carbon Hub is very grateful to the PDF download from www.zerocarbonhub.org following organisations for their involvement and contributions in developing these London Office recommendations. 62-68 Rosebery Avenue London EC1R 4RR Association for Environment Conscious Building (AECB) Aecom Milton Keynes Office Anser Project Managers NHBC House, Davy Avenue Barratt Developments PLC Milton Keynes MK5 8FP British Electrotechnical and Allied Manufacturers' Association (BEAMA) T 0845 888 7620 Building Research Establishment (BRE) F 0871 813 0569 Building Regulations Advisory Committee (BRAC) Construction Products Association (CPA) [email protected] Countryside Properties PLC www.zerocarbonhub.org Crest Nicholson PLC Davis Langdon Energy Saving Trust (EST) Fairview New Homes Ltd. Federation of Environmental Trade Associations (FETA) Federation of Master Builders (FMB) Fulcrum Consulting Good Homes Alliance (GHA) Heating and Hotwater Industry Council (HHIC) Heatrae Sadia Home Builders Federation (HBF) Homes and Communities Agency (HCA) Hot Water Association (HWA) House Builders Association (HBA) Ian Andrews Associates Inbuilt Leeds Metropolitan University Lighting Industry Federation (LIF) London Borough of Barnet (Building Control) Haringey Council (Planning) National House-Building Council (NHBC) Richard Partington Architects Robust Details Limited (RDL) Royal Institute of British Architects (RIBA) Space Air University College London (UCL) Vent Axia WWF Observers Department for Communities and Local Government Department of Energy and Climate Change Scottish Government Welsh Assembly The views and recommendations within this report are those of the Task Group and do not necessarily reflect the views of Government 2 Defining a Fabric Energy Efficiency Standard for zero carbon homes Contents Executive summary .................................................................................................... 6 Introduction ............................................................................................................... 16 Task Group process ................................................................................................. 18 Policy level considerations........................................................................................ 20 Technical considerations .......................................................................................... 22 Defining the scope of energy efficiency .................................................................... 23 Technical investigations ........................................................................................... 30 Definition of dwelling types ....................................................................................... 30 Financial investigations ............................................................................................ 41 Capital cost of Energy Efficiency .............................................................................. 45 Whole life cost modelling exercise ............................................................................ 48 Metric investigations ................................................................................................. 50 Performance standard .............................................................................................. 52 Preferred metric – Performance with design guidance ............................................. 53 Task Group wider analysis ....................................................................................... 55 Defining the Fabric Energy Efficiency Standard ....................................................... 58 Demonstrating compliance ....................................................................................... 69 Introduction timeframe for the Fabric Energy Efficiency Standard ............................ 70 Policy definition announcement date ........................................................................ 71 Requirements for future work ................................................................................... 72 Appendices ............................................................................................................... 75 3 Defining a Fabric Energy Efficiency Standard for zero carbon homes List of figures Figure 1: Zero carbon policy relationships ............................................................... 16 Figure 3 Task Group Structure ............................................................................... 19 Figure 4: Task Group assessment matrix ................................................................ 20 Figure 5: Task Group scope of activity .................................................................... 22 Figure 6: Scope 1 Dwelling energy demand only .................................................... 24 Figure 7: Scope 2 Dwelling energy demand and appliance efficiency of energy conversion ................................................................................................ 25 Figure 8: Scope 3 Dwelling energy demand, efficiency of energy conversion and energy distribution ................................................................................... 26 Figure 9: Task Group definition of the energy efficiency standard scope ............... 27 Figure 10: Consultation on scope of standard .......................................................... 29 Figure 11: Core dwelling types for energy, buildability and financial modelling ........ 30 Figure 12: Construction specifications for energy, buildability and financial modelling ................................................................................................................................. 31 Figure 13: Indicative masonry wall construction sections for Spec A – D ................. 33 Figure 14: Full fill cavity masonry wall construction sections .................................... 34 Figure 15: Partial fill cavity masonry wall construction sections ................................ 34 Figure 16: Timber frame wall construction sections .................................................. 35 Figure 17: Suspended beam and block floor construction sections .......................... 35 Figure 18: Ceiling level insulated ceiling construction sections ................................ 36 Figure 19: Event construction opinion boards........................................................... 37 Figure 22: Initial energy modelling results – Energy demand breakdown ................. 40 Figure 23: 70% Carbon Compliance capital costs (Second Quarter 2009) .............. 43 Figure 24: Consultation feedback on 70% Carbon Compliance capital costs ........... 44 Figure 25: Additional capital cost compared to baseline for energy efficiency measures only (Second Quarter 2009) ................................................... 46 Figure 26: Consultation feedback on the energy efficiency related capital costs ..... 47 Figure 28: Summary whole life costs for 70% Carbon Compliance semi detached house over 60 years with differing energy inflation rates ........................ 49 Figure 27: Whole life costs for 70% Carbon Compliance semi detached house over 60 years .......................................................................................... 49 Figure 30: Illustration of the implications of a Performance metric ........................... 52 Figure 31: Consultation feedback on the preferred metric ........................................ 54 Figure 32: Task group Assessment Matrix completed .............................................. 56 Figure 33: Pros and cons of setting a multiple level ................................................. 59 4 Figure 35: Thermal mass sensitivity analysis ........................................................... 62 Figure 36: Orientation sensitivity analysis ................................................................ 63 Figure 37: Air permeability sensitivity analysis ......................................................... 64 Figure 38: Hot water (DHW) system related internal gains sensitivity analysis ........ 65 Figure 39: Task Group recommended Fabric Energy Efficiency Standard ............... 66 Figure 40: Example of the relationship between build specification and standard level ......................................................................................... 67 Figure 42: Consultation feedback on the degree of challenge represented by the suggested performance requirements .............................................. 68 Figure 43: Demonstrating compliance with the Standard ......................................... 69 Figure 46: Overview of supplementary work required .............................................. 72 5 Executive The context In December 2008 Government consulted on the definition of zero carbon homesb to provide summary industry with a clearer concept of what this would mean from 2016 onwards. The definition is based around a hierarchical approach to achieving ‘zero carbon’ (Figure i): 1. Ensuring an energy efficient approach to building design 2. Reducing CO2 emissions on-site via low and zero carbon technologies and connected heat networks 3. Mitigating the