Radian Group. Performance Standards. Date November Author Rachel Mitchell. Version Final (V2)

Transcription

1 Radian Group Performance Standards Date November 2011 Author Rachel Mitchell Version Final (V2)

2 Radian Building performance standards Contents Introduction... 3 Design considerations for Radian Housing... 3 Improving building performance... 5 Fabric Energy Efficiency Standard and the Code for Sustainable Homes... 5 Minimum Standards for Radian... 6 Improving Building Fabric... 6 Building services... 7 Achieving ENE 1 of the Code for Sustainable Homes and Zero Carbon Homes Appendix one - Building Standards Zero Carbon Homes Passivhaus Standards Further reading and reference material Appendix Two Methodology for the Building Performance Standards Low and zero carbon technologies Building Services House types Appendix Three -Construction Floors Roofs Walls

3 Radian Building performance standards Introduction This document brings together at the changes to Approved Document L1A 2010 of Building Regulations, the technical guidance for the Code for Sustainable Homes November 2010 and the current thinking from the Zero Carbon Hub on the 2016 definition of a Zero Carbon Home. These documents are the background to the priorities and minimum standards of Radian on the energy performance of their new homes. These building performance standards will be integrated into The Employee s Requirements, and look at the interrelation between building fabric and renewable technologies and the preferred approach of Radian in achieving Code level 3, Code level 4 and Zero Carbon Homes. The emphasis will be on improving the building fabric first and this will take on board the principals of the German Passivhaus Standards and how these can be related to achieving Approved Document Part L1A of Building Regulations compliance now, and beyond to 2013 and The purpose of developing these design standards is to foster an approach to development which complies with current standards and also lays the foundation for the predicted changes to Part L1A of Building Regulations in 2013 and 2016, by adopting principals now which will assist in meeting those higher standards for energy use and carbon emissions. Examples of design compliance will be given for wall, roof and floor constructions but one of the purposes of the document is to allow flexibility while setting out clear guidance on what is expected in terms of future buildings energy performance. Design considerations for Radian Housing Improving the building fabric and building service is the first step to consider before adding any low or zero carbon technologies. This reduces the heat loss and energy demand of the building, keeps the running costs to a minimum and helps in reducing fuel poverty. In addition it future proofs the home, as any bolt on technologies will need to be replaced or upgraded at a future date. Figure 1 Building fabric The Building Fabric is defined as the building envelope and building services The Building Envelope includes all the external elements of the building; wall, floor, roof, windows and doors. The Building Services include all services that can reduce the energy demand of the building e.g. low energy lighting, a more efficient boiler, mechanical ventilation with heat recovery, improved cylinder insulation and energy efficient appliance 3

4 Radian Building performance standards Figure 2 Improving the building fabric Improving the building envelope reduces heat loss by: Increasing insulation Reducing thermal bridging Increasing airtightness Improving the building services reduces energy demand by: Improving the efficiency of heating systems Adding more insulation to hot water cylinders Installing mechanical ventilation with heat recovery Supplying 100% low energy lighting Overheating In the summer highly insulated and airtight homes may overheat. Overheating can be avoided by designing in details e.g. cross ventilation overhanging eaves, solar shading devices, thermal mass and night time ventilation. Homes with large areas of west facing glazing tend to overheat the most. This can be considered in the design and orientation of new homes This approach should be used when achieving the mandatory ENE 1 credit for Code level 3, Code level 4 and Zero Carbon Homes and the details of these standards can be founding appendix 1. Code level 3 It is the intention of Radian that all homes, which are only required to meet Code level 3, do so without the use of low or zero carbon technologies. The exception to this is when a development is off gas and details are given later on the minimum fabric requirements in this situation. Code level 4 and Zero Carbon Homes There are two options to achieve these higher levels 1. Use improvements to the building fabric 2. Add low or zero carbon technologies to an improved building fabric 4

5 Radian Building performance standards Improving building performance All new homes should firstly look to improve the building envelope before considering low and zero carbon technologies to deliver the following. Lower energy bills for the life of the building and protection from fuel poverty Lower carbon emissions Ease of use and a passive approach where possible Comfortable internal temperatures and environment Low maintenance and renewal costs Fabric Energy Efficiency Standard and the Code for Sustainable Homes The Code for Sustainable Homes Nov 2010 has a new credit Fabric Energy Efficiency (ENE 2), which awards credits for improving the building envelope. The Fabric Energy Efficiency Standard is the energy demand for space heating and cooling expressed in kilowatt-hours of energy demand per square meter (kwh/m 2 /year). Apartment blocks And mid terrace Figure 4 Fabric energy efficiency standards ENE 2 Dwelling type End terrace, semi detached house and detached house Fabric energy efficiency kwh/m 2 /year ENE 2 Credits for the Code for Sustainable Homes Comment Minimum requirement for Radian Homes * Possible standard for 2013 Building Regulations Part L1A Mandatory for Level 5 and 6 and possible standard for Zero Carbon Homes < Closer to Passivhaus Standard Radian will use these standards, together with the SAP 2009 rating to ensure that new homes meet minimum standards for building fabric and services 5

6 Radian Building performance standards Therefore it is the preference that all new house types must meet the following energy demand and score at least 3 credits under ENE 2 Fabric Energy Efficiency Standard. In addition all new homes should have at least a B rating in the SAP assessment and a B in the Environmental Impact rating. Apartment blocks, mid terrace Figure 3 Minimum ENE 2 requirements for Radian Dwelling type Fabric energy efficiency kwh/m 2 /year End terrace, semi detached house and detached Code for Sustainable Homes Credits B SAP/EI 2009 Rating Figure 4 shows how this standard corresponds to the all of the available credits for ENE 2- Fabric Energy Efficiency Standard Minimum Standards for Radian The following are seem at the critical design standard which Radian would want to see in all new homes. Improving Building Fabric Air Permeability All homes should achieve a minimum air tightness of 3 m 3 /hm and preferably 1 m 3 /hm This level of air tightness will require all homes to be fitted with Mechanical Ventilation with Heat Recovery (MVHR) of which there are minimum performance requirements (see below) Windows and doors All windows and doors should have a minimum U value of 1.4 W/m 2 K and preferably a U value of 1.2 W/m 2 K. Thermal bridge Thermal bridging is calculations in SAP 2009 have changed. Unless the default value of 0.15 W/m 2 K is used, individual thermal bridge details including Accredited Construction Details have to be individually measured and inputted. At the time of writing Enhanced Construction Details can be used, but they have to be imputed manually with an additional 0.2W/m 2 K confidence factor. 6

7 Radian Building performance standards Using Accredited Construction Details is highly recommended as this is a cost effective way of enhancing building performance. Once more Enhanced Construction Details become available these should also be considered. Building services Flue gas heat recovery systems (FGHRS) Flue gas heat recovery systems recover heat from the flue products to pre- heat the domestic water supply. By utilising a heat store within the devices energy recovered during space heating can also be used to off set the heat required for domestic hot water All houses with a combination gas boiler should, where possible be fitted with a gas flue heat recovery system, though it is recognised that not all boiler manufacturers are able to provide this device at present. The main manufacturers providing this at the time of writing are Alpha, Baxi, Potterton, Ravenheat and Ideal. Where applicable a combination boiler should be used as this works most efficiently with the FGHRS and there are less options if a regular boiler is used. It is acceptable for FGHRS not to be used in flats where space is more of an issue, Heating controls All homes should be fitted with a weather compensator as standard Waste water heat recovery Shower heat recovery units take heat from discharged waste shower water and heat the incoming supply of cold mains water to the shower inlet. These are passive units and once installed are low maintenance. Where possible shower heat recovery units could be installed in all new homes, especially those e.g. wheelchair units where there is only a shower for personal washing. MVHR All systems should have a maximum Specific Fan Power of 0.55w/l/s and the minimum efficiency of the heat exchanger of 90%. To assist with summer over heating in houses all units should have a summer bypass of the heat exchanger or use passive stack. The smaller size of apartments can minimise the benefits of summer bypass as the volume of air changed is less, and therefore whilst this is preferable, it is acceptable for units not to be fitted with summer bypass. 7

8 Radian Building performance standards Off gas It is recognised that there are limited heating options when mains gas is not available. One cost effective option would be to install an air source heat pump, however this must be coupled with good building fabric and services, to be an acceptable solution to Radian As the SAP 2009 assessment makes allowances within Target Emissions Rate (TER) for non gas heating solutions, it is possible to achieve Part L1A compliance with a lesser building fabric (compared to mains gas). Radian wishes to ensure that all new houses are of the same high standard to meet the requirements of energy efficiency and future proofing. As before, it is a preference of Radian that all homes should have a minimum fabric energy efficiency (FEE) standard based on ENE 2 of the Code for Sustainable Homes 2009 and achieve at least a B rating in the SAP assessment. This will be the same for homes designed to use an air source heat pump. Figure 5 Minimum ENE 2 requirements for Radian all heating systems Dwelling type Apartment blocks, mid terrace End terrace, semi detached house and detached Fabric energy efficiency kwh/m 2 /year ENE 2 Credits There are also considerable differences in the performances of heat pumps and an efficient air source heat pump with a good CoP (co-efficient of performance) will have a positive impact on both the SAP assessment and the effectiveness of this form of heating Below are a selection of Air Source Heat Pumps and the comparison of the CoPs as detailed in appendix Q of SAP Figure 6 Comparison of appendix Q data Model Heating Hot water Dalkin EKHBH008B + ERHQ006BV Mitsubushi ECODAN 5kW Worcester Greensource 6kW Kingspan Aeromax Plus 6kW

9 Radian Building performance standards By choosing an air source heat pump with a good CoP and meeting the minimum design standards for Radian in terms of airtightness and Accredited Construction Details, it is likely that the design performance to go beyond compliance with Part L1A and achieve the 25% reduction needed for Code level 4 of ENE 1 of the Code for Sustainable Homes. This higher code level can be achieved while still having considerable flexibility in the U values of floors, walls and roofs. Therefore meeting Code level 4 of ENE 1 is preferred minimum standard for all homes using an air source heat pump. 9

10 Radian Building performance standards Achieving ENE 1 of the Code for Sustainable Homes and Zero Carbon Homes The following section gives examples of three different house types Three bed end terraced or semi detached house Two bedroom mid terraced house Two bedroom mid floor low rise apartment Each house type has been modelled in NHER SAP software to show compliance with ENE 1 of the Code for Sustainable Homes for Code levels 3 and 4, and predicts based on current information what compliance with a Zero Carbon Homes may look like. Further detail of these standards can be found in appendix 1. The performance standards are based on the following approaches. Figure 7. Achieving Code levels for ENE 1 ENE 1 Code level 3 Building Regulations Compliance Base* Meeting Approved Documents L1A 2010 using building fabric and services alone ENE 1 Code level 4 Building Regulations Compliance + 25% improvement Base Meeting Approved Documents L1A 2010 using building fabric + low carbon technologies to achieve 25% improvement Better Exceeding Approved Documents L1A 2010 using building fabric + some low carbon technologies to achieve 25% improvement Best Passivhaus Standard for building fabric and services to exceed 25% improvement Zero carbon homes 11kgCO 2 /m 2 /year for end and mid terraced house 14kgCO 2 /m 2 /year for low rise apartment Base and Better Exceeding Approved Documents L1A 2010 using building fabric alone + low carbon technologies to achieve zero carbon home Best Passivhaus Standard for building fabric and services to achieve Code level 4 + low carbon technologies to achieve zero carbon homes *for some off gas solutions, in order to either achieve a B SAP rating or the minimum FEE requirements, this may result in an improvement over Part L1A. The tables show how different combinations of U values, building services and low and zero carbon technologies, based on Radians minimum standards can achieve different the Code levels for ENE 1 of the Code for Sustainable Homes 2010 and a Zero Carbon home. For three different house types. 10

11 Radian Building performance standards A three bed end of terraced house A two bed mid terraced house A two bed mid floor flat Further details for the specification of the house types used can be found in appendix three All the examples meet the preferred minimum standard of Radian all new homes achieve at least a SAP rating of B and achieve at least 3 credits for ENE 2 Fabric Energy Efficiency of the Code for Sustainable Homes ( Nov 2010) There are two sets of tables, dealing with a site with gas and the other without gas. For the sites without gas, the solar hot water options has not been used Code Level 3 It is the preference of Radian that for the Mandatory Credit Ene 1, all home achieve Code level 3 without the use of low or zero carbon technologies Two examples of how to achieve this are given, one gas and one off gas. Both the examples meet the preferred specification of having high levels of air tightness, an efficient MVHR system, better controls and more efficient use of the heating system. Generally Radian does not wish to use air source heat pumps and therefore a direct electrical solution is given as an alternative, for when there is no natural gas on site. In some situations, where direct electric heating is used, it may be necessary to use photo voltaics to offset some of the carbon emissions to achieve Code level 3 and B rating in SAP and EI. In this instance this is an acceptable solution, providing there is a good building fabric and all the minimum standards are met Code level 4 (Compliance with Part L1A 2013) Three examples are given to achieve the 25% improvement over Approved Document Part L1A 2010 of Building Regulations. 11

12 Radian Building performance standards 1. Base The specification to achieve Building Regulations compliance is used and photo voltaics (PV) are added to achieve code level 4 for ENE 1 2. Better A better building fabric is used, which gives more choice for a low or zero carbon technology and solar hot water is added. 3. Best A Passivhaus specification is used, which will more that comply with the requirements of Code level 4 for ENE 1 without the use of low or zero carbon technologies Zero Carbon Homes (Compliance with Part L1A 2016) These have been modelled in SAP This is a design performance assessment and the current thinking is that by 2016 compliance will be based on built performance. The gap between the two is unknown at this stage but could, according to the Zero Carbon Hub, range between 0kg and 6kg CO 2 /m 2. There is also an assumption that the carbon content of fuels will increase and the current thinking is that the Carbon Compliance levels will be based on the higher carbon emissions from gas and electrify. Further details can be found in appendix 1. Therefore these examples are based on a best guess and probably will change as the picture becomes clearer. Three examples are given modelled in SAP 2009 with the DER adjusted using the different carbon content of the fuels used. 1. Base The specification to achieve code level 4 for ENE 1 using solar hot water is used and sufficient photo voltaics added instead of the solar hot water, to achieve the standard for a zero carbon home 2. Better A better building fabric is used and solar hot water added to meet the standard 3. Best The Passivhaus specification is used and shower waste heat recovery added to meet the zero carbon standard with the minimum use of technologies 12

13 Radian Building performance standards Code level 3 Meeting part L1A Code level 4 (25% improvement Part L1A 2010) 3 BED END TERRACED HOUSE Zero carbon homes ( Compliance Part L1A 2016) Minimum DER 11 kgco 2 /m 2 /year (using 2016 emissions factors) Description On gas Photo voltaics solar hot water Passivhaus Standard Enhanced building Fabric plus PV Further Enhanced building Fabric plus solar hot water Heat loss elements U values W/m 2 K Floors Wall Roof Windows /doors 1.4/ / / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes yes Thermal Bridge details ACD* ACD* ACD* 0.01 ACD* Heating system Heating and hot water Low or zero carbon technology Gas boiler + FGHRS Gas boiler + FGHRS Gas boiler + weather compensator 0.9kWp PV 3m 2 flat plate solar hot water Gas boiler + weather compensator Gas boiler + FGHRS Gas boiler + weather compensator 1.4 kwp PV 3.2m 2 flat plate solar hot water + shower waste heat recovery Passivhaus- Zero carbo home Standard Gas boiler 90.2% efficient + weather compensator Shower waste water heat recover RESULTS DER in SAP 2009 ( 2016 assumed emission rates in brackets) TER DER (10.87) 9.95 (10.85) 9.78 (10.64) Improvement -1.24% % % % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 60 kwh/m 2 : MEETING CODE LEVE 5/6 MINIMUM STANDARDS 46 kwh/m 2 SAP rating of B or more FEE SAP B 82 B 86 B 85 B 86 B 89 B 88 B 87 EI B 85 B 89 B 88 B 90 A 94 A 92 A 92 13

14 Radian Building performance standards 2 BED MID TERRACED HOUSE Code level 3 Code level 4 Meeting part L1A 2 Description On gas Photo voltaics solar hot water Passivhaus Standard Zero carbon homes. Minimum DER 11 kgco 2 /m 2 /year (using 2016 emissions factors) Enhanced building Fabric plus PV Further Enhanced building Fabric plus solar hot water Heat loss elements U values W/m 2 K Floors Wall Roof Windows /doors 1.4/ / / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes yes Thermal Bridge details Heating and hot water Passivhaus- Zero carbo home Standard ACD* ACD* ACD* 0.01 ACD* Heating system Gas boiler + Gas boiler + FGHRS Gas boiler + weather Gas boiler + Gas boiler +FGHRS Gas boiler + weather 90.2% efficient Gas weather compensator weather compensator boiler + FGHRS compensator compensator Low or zero carbon technology 0.7Wp 2 m 2 flat plate solar hot water RESULTS 1.1 kwp PV 2.m 2 flat plate solar hot water + Shower waste heat recovery Shower waste water heat recovery TER DER (10.58) 9.70 (10.53) 9.98 (10.85) Improvement -0.22% % % % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 48 kwh/m 2 : MEETING CODE LEVE 5/6 MINIMUM STANDARDS 39 kwh/m 2 SAP rating of B or more FEE SAP B 83 B 87 B 86 B86 B 90 B 87 B 87 EI B 87 A 91 B 90 B 90 A 94 A 93 A 92 14

15 Radian Building performance standards Code level 3 Meeting part L1A Code level 4 2 BED MID FLOOR APPARTMENT ( LOW RISE) Zero carbon homes. Minimum DER 14 kgco 2 /m 2 /year (using 2016 emissions factors) Description On gas Photo voltaics solar hot water Passivhaus Standard Enhanced building Fabric plus PV Further Enhanced building Fabric plus solar hot water Heat loss elements U values W/m 2 K Floors/roof n/a n/a n/a n/a n/a n/a n/a Wall Semi exposed wall Windows /doors 1.4/ / / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes yes Thermal Bridge details Heating and hot water ACD* ACD* ACD* 0.01 ACD* Heating system Gas boiler + weather Gas boiler +weather Gas boiler + weather Gas boiler + weather compensator compensator compensator compensator Communal gas boiler plus shower waste heat recovery Passivhaus- Zero carbo home Standard Communal gas boiler Gas boiler + weather compensator plus Low or zero carbon technology 0.6kWp 1.5 m 2 flat plate solar hot water 0.6 kwp PV 1.m 2 flat plate solar hot water (shared system) + shower waste heat recovery Shower waste water heat recovery RESULTS DER in SAP 2009 ( 2016 assumed emission rates in brackets) TER DER (13.70) (13.68) (13.23) Improvement -1.00% % % % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 48 kwh/m 2 : MEETING CODE LEVE 5/6 MINIMUM STANDARDS 39 kwh/m 2 SAP rating of B or more FEE SAP B 83 B 86 B 85 B 85 B 87 B 86 B 85 EI B 87 B 90 B 90 B 90 A 92 B 86 A 91 15

16 Radian Building performance standards 3 BED END TERRACED HOUSE OFF GAS Code level 3 Code level 3 and 4 Code level 4 (25% improvement Part L1A 2010) Zero carbon homes ( Compliance Part L1A 2016) Minimum DER 11 kgco 2 /m 2 /year (using 2016 emissions factors) Description Off gas Off Gas Photo voltaics Passivhaus Standard Enhanced building Fabric plus PV Passivhaus- Zero carbon home Standard Heat loss elements U values W/m 2 K Floors Wall Roof Windows /doors 1.4/ / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes Thermal Bridge details ACD* ACD* ACD* 0.01 ACD* 0.01 Heating system Heating and hot water Low or zero carbon technology Electric panel heater and immersion heater 1.1 kwp This is needed to achieve a B SAP and EI rating Air source heat pump and weather compensator Electric storage heater and immersion heater Electric panel heater and immersion heater Electric panel heater and immersion heater 1.5 kwp PV Shower waste water heat recover 3.4 kwp PV Electric panel heater and immersion heater Shower waste water heat recover 0.9 kwp PV RESULTS TER DER (10.59) ( 10.53) Improvement % % % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 60 MEETING CODE LEVE 5/6 MINIMUM STANDARDS 46 kwh/m 2 kwh/m 2 : SAP rating of B or more FEE SAP B 82 B 82 B 83 B 86 A 96 A 95 EI B 81 B 84 B 82 B 84 A 95 A 93 16

17 Radian Building performance standards 2 BED MID TERRACED HOUSE OFF GAS Code level 3 Code level 3 and 4 Meeting part L1A Code level 4 (25% improvement Part L1A 2010) Zero carbon homes ( Compliance Part L1A 2016) Minimum DER 11 kgco 2 /m 2 /year (using 2016 emissions factors) Description Off gas Off Gas Photo voltaics Passivhaus Standard Enhanced building Fabric plus PV Passivhaus- Zero carbon home Standard Heat loss elements U values W/m 2 K Floors Wall Roof Windows /doors 1.4/ / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes Thermal Bridge details ACD* ACD* ACD* 0.01 ACD* 0.01 Heating system Heating and hot water Low or zero carbon technology Electric storage heater and immersion heater 0.4 kwp This is needed to achieve a B SAP and EI rating Air source heat pump and weather compensator Electric storage heater and immersion heater Electric panel heater and immersion heater Electric storage heater and immersion heater 1.2 kwp PV Shower waste water heat recover 2.5 kwp PV RESULTS TER Electric storage heater and immersion heater Shower waste water heat recover 1.3 kwp PV DER (10.65) ( 10.43) Improvement -8.73% % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 48 kwh/m 2 : SAP rating of B or more MEETING CODE LEVE 5/6 MINIMUM STANDARDS 39 kwh/m 2 FEE SAP B 87 B 84 B 91 B 88 A 100 A 96 EI B 81 B 85 B 85 B 85 A 95 A 94 17

18 Radian Building performance standards 2 BED MID FLOOR FLAT LOW RISE OFF GAS Code level 3 Code level 3 and 4 Meeting part L1A Code level 4 (25% improvement Part L1A 2010) Zero carbon homes ( Compliance Part L1A 2016) Minimum DER 14 kgco 2 /m 2 /year (using 2016 emissions factors) Description Off gas Off Gas Photo voltaics Passivhaus Standard Enhanced building Fabric plus PV Passivhaus- Zero carbon home Standard Heat loss elements U values W/m 2 K Floors n/a n/a n/a n/a n/a n/a Wall Roof n/a n/a n/a n/a n/a n/a Windows /doors 1.4/ / / / / /0.8 Ventilation Air permeability MVHR yes yes yes yes yes yes Thermal Bridge details ACD* ACD* ACD* 0.01 ACD* 0.01 Heating system Heating and hot water Low or zero carbon technology Electric storage heater and immersion heater 0.3 kwp This is needed to achieve a B SAP and EI rating Air source heat pump and weather compensator Electric panel heater and immersion heater 18 Electric panel heater and immersion heater Electric panel heater and immersion heater 1 kwp PV Shower waste water heat recover 1.6 kwp PV Electric panel heater and immersion heater Shower waste water heat recover 0.4 kwp PV RESULTS DER in SAP 2009 ( 2016 assumed emission rates in brackets) TER DER (13.46) (13.78) Improvement -8.06% % % % % MEETING RADIANS MINIMUM STANDARDS Fabric Energy Efficiency FEE 48 MEETING CODE LEVE 5/6 MINIMUM STANDARDS 39 kwh/m 2 kwh/m 2 : SAP rating of B or more FEE SAP B 87 B 84 B 87 B 89 A 94 A 93 EI B 81 B 86 B 85 B 86 A 92 B 90

19 Appendix one Building Standards Appendix one - Building Standards Approved Document Part L1A of Building Regulations The 2016 Part L1A zero carbon requirement for new buildings is only a few years away and to help the transition, there will be an interim set of revisions to the Regulations in These will act as a stepping stone to the challenging performance requirements to come and among other changes, are likely to place more emphasis on narrowing the gap between as designed and as built performance. Whilst the 2013 Part L requirements are yet to be decided and are still subject to consultation, the flowing are being considered Further reductions in carbon emissions based on current Code level 4 requirements Increases in minimum air tightness Measuring as built rather than design performance Setting minimum Fabric Energy Efficiency standards based on the Code for Sustainable Homes The figure below shows the relationship between the Fabric Energy Efficiency Standards and the possible changes to Approved Document Part L1A Figure 1 Fabric energy efficiency standards ENE 2 and Compliance with Part L1A Apartment blocks And mid terrace Dwelling type End terrace, semi detached house and detached house Fabric energy efficiency kwh/m 2 /year ENE 2 Credits for the Code for Sustainable Homes Comment Minimum requirement for Radian Homes * Possible standard for 2013 Building Regulations Part L1A Mandatory for Level 5 and 6 and possible standard for Zero Carbon Homes < Closer to Passivhaus Standard Compliance with Part L1A in 2016 will be based on the definition of a Zero Carbon Home, details of which can be found later in this document 19

20 Appendix one Building Standards The Code for Sustainable Homes 2010 is the current measure for the sustainability of new homes. It provides a framework within which home builders can be recognised for going beyond Building Regulations on both energy efficiency and range of other sustainability issues. The Code awards new homes a Code rating from 1-6 based on their performance against nine sustainability categories as shown in Figure 1. Figure 1. Code 2010 categories and total number of points available for each category Code Categories Number of Category Weighed credits weighting value of available factor each credit Ene 1-9 *Energy and CO 2 Emissions Ene 1 Dwelling Emission Rate 10 Ene 2 Fabric Energy Efficiency 9 Ene 3 Ene 4 Ene 5 Ene 6 Ene 7 Ene 8 Ene 9 Energy Display Devices Drying space Energy Labelled White goods External Lighting Low or Zero Carbon Energy technologies Cycle Store Home Office Total % 1.17 Wat 1-2 *Water 6 9% 1.50 Mat 1-3 *Materials % 0.30 Sur 1-2 *Surface Water Run off 4 2.2% 0.55 Was 1-3 *Waste 8 6.4% 0.80 Pol 1-2 Pollution 4 2.8% 0.70 Hea 1-4 Health and Wellbeing 12 14% 1.17 Man 1-4 Management 9 10% 1.11 Eco 1-5 Ecology 9 12% 1.33 Total % * Categories that have minimum mandatory requirements The Building Performance Standards developed in this document, are a guide to help interpret the different levels of the Code for Sustainable Homes from 3-6 into design and construction details for the Ene 1, Ene 2 section of the Code. 20

21 Appendix one Building Standards Ene 1 is the Dwelling Emission Rate (DER) section of the Energy and CO 2 Emissions category. To pass Building Regulations 2010 DER must be equal to or less than the Target Emissions Rate (TER). This is calculated using SAP 2009 (Standard Assessment Procedure) which is the approved methodology for the rating the energy performance of a home. DER and TER are defined below. The Dwelling Emission Rate (DER) is the actual carbon dioxide emissions in kg per m 2 for the building. The Target Emission Rate (TER) is the maximum allowable carbon dioxide emissions per m 2 for energy in use in heating, hot water and lighting in a home which meets Building Regulations. Ene 1 is a mandatory credit within the Code for Sustainable Homes assessment, and in the November 2010 Technical Guide the following improvements of DER over TER must be achieve in order to obtain the following Code levels Figure 2Improvements of DER over TER to achieve higher Code levels ( Code level 3 Code level 4 Compliance with Approved Document L1A % improvement 2010 DER/TER Code level 5 100% improvement 2010 DER/TER Zero net CO 2 emissions ( all carbon Code level 6 emissions associated with the running of the home off set on site) Now that there is a new definition of a zero carbon home, it may be that Code levels 5 and 6 are redefined to be in line with this definition, of they may remain as exemplar standards which go beyond the requirements of Building Regulations. The Zero Carbon Hub is currently considering this issue. Ene 2 looks at Fabric Energy Efficiency and gives credits for reducing the energy demand of a dwelling and thus futures proofing CO 2 reductions for the life of that dwelling. The Fabric Energy Efficiency Standard is the energy demand for space heating and cooling expressed in kilowatt-hours of energy demand per square meter (kwh/m 2 /year). 21

22 Appendix one Building Standards The figure below show the Fabric Energy Efficiency Standings being used in the Code for Sustainable Homes and their relationship to Part L1A of Building Regulations. Apartment blocks And mid terrace Figure 3Fabric energy efficiency standards ENE 2 Dwelling type End terrace, semi detached house and detached house Fabric energy efficiency kwh/m 2 /year ENE 2 Credits for the Code for Sustainable Homes Comment Minimum requirement for Radian Homes * Possible standard for 2013 Building Regulations Part L1A Mandatory for Level 5 and 6 and possible standard for Zero Carbon Homes < Closer to Passivhaus Standard The Building Performance Standards developed by Radian will focus on scoring higher credits in this section by specifying minimum standards for the building fabric and increasing energy efficiency. Code level requirements It is still a requirement of the Homes and Communities Agency that all new homes with grant subsidy reach level 3 of the Code for Sustainable Homes, which for Ene 1 is compliance with Approved Document L1A In addition many local authorises are starting to include the Code for Sustainable Homes within their own planning policies and have set local standards for new homes. 22

23 Appendix one Building Standards Zero Carbon Homes The Zero Carbon Hub have been commissioned by the Government to provide a definition of what a zero carbon home will be in This has not been an easy task and a number of scenarios have been considered before the final definition has been agreed on. Previously, to achieve Code level 6 (which was the old definition of a zero carbon home) all the carbon emissions which result from heating, hot water, fixed lights and building services taken from the SAP assessment plus the emissions estimated from appliances and cooking had to be offset on site. This meant that there needed to be a significant improvement of DER over TER ( 140% 160%) A zero carbon home has been redefined by the Zero Carbon Hub. The government commitment to use this new definition was made in the 2011 Budget s Plan for Growth document. This new definition has several significant changes from the original definition of a zero carbon home 1. Only emissions cover by part L1A of Building Regulations (heat, fixed lighting, hot water and building services) are considered. This means only the carbon emissions calculated in the SAP assessment will be included in the assessment of a zero carbon home 2. Of these emissions, not all need to be mitigated on site as some can be off set using allowable solutions. These allowable solutions are being defined and details are found later in the document. 3. Rather than measuring building performance as a percentage reduction in DER over TER, minimum built performance emissions from new homes should be required not to exceed the following limits 10kgCO 2 /m 2 /year detached houses 11kgCO 2 /m 2 /year for other houses ( semi detached, terraced etc) 14kgCO 2 /m 2 /year for low rise apartments ( consultation is still on going for the built performance standard for high rise apartments) 23

24 Appendix one Building Standards The recommendation is also for carbon compliance to be assessment across the whole of the development site instead of the individual dwellings on site. Whist they cannot be directly compared, the Zero Carbon Hub has given the following comparison with SAP 2006 and the approximate improvements of DER over TER Figure 4 Comparison of SAP 2006 and Zero Carbon Hub Standards House type Zero carbon minimum standards Approximate improvement DER /TER 2006 regulations Detached house 10kgCO 2 /m 2 /year 60% All other house types 11kgCO 2 /m 2 /year 56% Low rise flats 14kgCO 2 /m 2 /year 44% One of the major changes within the definition of a zero carbon home is that compliance will be on the as built performance rather than the design performance which is what the SAP assessment currently is. This has been introduced because post occupancy evaluation studies have show that there is a gap between the predicted energy use at design stage and the actual energy use one the building is occupied. The Zero Carbon Hub think this gap could be between 0Kg and 6kg of CO 2 /m/ year. It is also predicated that the carbon content of fuel (the emissions factors) will change as the mix of fuels use to generate grid electricity changes and the increase in the amount of imported gas used. As the carbon content of fuel increases so the Dwelling Emission Rates will increase (DER). These predicted changes in fuel emissions are summarised below. Figure 5 Carbon Content of Fuel 2016 Fuel Current carbon content 2016 Carbon content Electricity Kg per kwh Kg per kwh Electricity generated on site Kg per kwh Kg per kwh Mains gas Kg per kwh Kg per kwh Wood pellets Kg per kwh Kg per kwh Wood chips Kg per kwh Kg per kwh 24

25 Appendix one Building Standards Whilst these changes are small they can have a significant impact on a dwellings overall carbon emissions This increase in the carbon content of fuel has been added in to the assessment of Dwelling Emission Rate (DER) when looking at Zero Carbon Homes in the examples. Passivhaus Standards The Passivhaus standard is a German design pioneered by Dr Wolfgang Feist who is head of building physics at the University of Innsbruck. Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling, They are built with high level of detailing and design and constructed according to the principles developed by the Passivhaus Institute in Germany. A Passivhaus will typically achieve a 75% reduction in space heating requirements compared to standard practice within the UK and provides a robust methodology to help the industry achieve the 80% reduction in carbon emissions that are the legislative target for the UK Government. The Passivhaus standard requires A maximum space heating and cooling demand of less than 15kWh/m 2 or a maximum heating and cooling load of less than 10 W/m 2 A maximum total primary energy demand of 120kWh/ m 2 An air change rate of no more than 0.6air changes per hour To achieve this a Passivhaus typically with have Very high levels of insulation minimum U values of 0.15 W/m 2 K for all elements Extremely high performance windows with insulated frames (whole window U value of 0.8 W/m 2 K Airtight building fabric with mechanical ventilation with heat recovery Thermal bridge free design and construction Use of solar gain through south facing windows Control of overheating through design and solar shading The benefits of the Passivhaus approach are to produce a home with very high levels of internal comfort with very low energy bills for heating and hot water, which protect against rising fuel prices and fuel 25

26 Appendix one Building Standards poverty. The design has been thoroughly tested through post occupancy monitoring and the results repeatedly show that design and built performance are consistent. Further reading and reference material Getting Warmer: a field trial of heat pumps The Energy Saving Trust September 2010 Carbon Compliance: What is the appropriate level for 2010? Interim Report Zero Carbon Hub December 2010 Carbon Emissions Factors for Fuels Zero Carbon Hub October 2010] Modelling 2016 using SAP 2009 technical guide Zero Carbon Hub March 2011 The Government s Standard Assessment Procedure for Energy Rating of Dwellings 2009 Published on behalf of DECC by the BRE March 2010 The Code for Sustainable Homes Technical Guide November 2010 Department of Communities and Local Government November 2010 Allowable Solutions for Tomorrows New Homes Towards and Workable Solution Zero Carbon Hub July

27 Appendix Two Methodology for the Building Performance Standards Appendix Two Methodology for the Building Performance Standards The examples given to illustrate how to achieve the required DER for the different levels of the Code for Sustainable Homes and achieving the Zero Carbon Homes standards, were created by modelling three different property types, in NHER SAP 2009 software using the general specification shown in Table 1 below. Table 1 Specification for the three property types 3 bed end terrace 2 Bed Mid terrace 2 bed mid floor apartment Floor area 85m 2 74m m 2 Roof area South facing 25m 2 South facing 20m 2 Communal flat roof Build date 2011 Region S England Location Low rise urban Dense urban Sheltered sides 1 2 Heating systems Generally Individual unless specified Party Walls All sealed and filled U=0 Heating systems gas boiler 88.9 % efficient ( SEDBUK 2009) Vailant Ecotech plus 824 Maximum standing heat loss Maximum standing heat loss Solar Hot Water 1.85kWh per day 250 litres ( solar hot 1.40kWh per day 180 litres ( solar Store water only) hot water only)n/a Distribution system Flue Gas Heat Recovery system MVHR Unless specified MVHR for Passivhaus certified product Shower waste heat recovery systems Internal lighting Overheating Thermal Mass Parameter Orientation Itho HRU ECO 4 SFP 0.46 w/l/s 91% efficient Summer by pass Radiators Zenex gas saver Paul Thermos 300 DC Itho SHRU % low energy Cross ventilation with windows fully open half the time Medium North/South Itho Advance SFP 0.37 w/l/s 90% efficient No supper by pass No cross ventilation windows fully open half the time Medium 27

28 Appendix Two Methodology for the Building Performance Standards Low and zero carbon technologies Solar hot water and photo voltaics Where solar hot water and photo voltaics are specified, it is assumed that the system is south facing on a 30 o angle with little or no shading Air Source heat pumps Where an air source heat pump has been specified a Dalkin EKHBH008B + ERHQ008BVS, with a weather compensator and controlled with a programmer, TRV s and bypass Building Services Flue gas heat recovery systems Flue gas heat recovery systems work with a domestic boiler, and using a heat exchanger, extract heat from the exhaust flue gases and use to heat stored water which is then used the preheat the cold water supply to the boiler. This technology can be used with a combination or a system boiler. Manufactures information estimates that a gas flue heat recovery devices will save up to 37% on energy required to deliver hot water. Pre-heating incoming cold water supply will be particularly effective in winter. Flue gas heat recovery systems are appendix Q eligible which means they can be used in the SAP assessment to reduce Dwelling Emission Rate (DER). When adding a flue gas heat recovery system you have to take off the weather compensator to prevent double counting. The impact on the SAP assessment using the flue gas heat recovery system can be seen in the table below. The Flue gas heat recovery unit was not used on the apartments, where space in the kitchen may be limited Table 2 Flue gas heat recovery systems : energy saved from appendix Q data standard 3 bed house 2 bed house Compliance with part L1A 392 kwh/year 283 kwh/year Better building fabric 323 kwh/ year 237 kwh/year Shower Heat Recovery Systems Shower heat recovery systems take heat from discharged waste shower water and heat the incoming supply of cold mains water to the shower inlet. These are passive units and once installed are low maintenance. As this is a relatively new technology it was only used on the Passivhaus to help achieve the carbon compliance 28

29 Appendix Two Methodology for the Building Performance Standards for a zero carbon home. These systems are also appendix Q approved and the impact on energy saved can be seem in the table below Table 3 Shower heat recovery systems : energy saved from appendix Q data Standard 3 bed house 2 bed house 2 bed apartment Passivhaus 438 kwh/year 408 kwh/year 361 kwh/year House types Passivhaus Standards It is not possible to do a direct comparison with the Passivhaus Standard and a SAP assessment as the build form and services are measured in very different ways. The main difference being that for a Passive House Planning Package (PHPP) assessment external measurements are taken rather than internal measurements which is the case for SAP. This means that SAP tends to underestimate heat loss whereas PHPP will over estimate it. There are also difference in how usable floor space, MVHR, windows, solar gain and over shading are assessed. The certification of a Passivhaus dwelling is more complex that a SAP assessment and is very site specific, and therefore the thermal values given are for guidance only. The three bed roomed house was modelled in Passivhaus Planning Package (PHHP) and the values used to obtain compliance then inputted into SAP. These values were then used for the 2 bed house and the 2 bed apartment. Terraces houses and apartment blocks are assessed on the whole row or apartment building in PHPP rather than individual houses, which is the approach of SAP. As this assessment will depend on so many different variables these values are indicative rather the absolute. For the Passivhaus standard house there is additional southerly glazing to maximise solar gain and the northerly windows have been reduced in size 29

30 Appendix Three Construction Appendix Three -Construction This section looks at some potential construction solutions to meet some of the higher U values needed to achieve the higher levels of the Code for Sustainable Homes and Zero carbon homes. These U values have been used in the Examples on pages Figure 1 Example U values for Code level 4 and Zero Carbon Homes Code 4 Zero Carbon Passivhaus Floors Walls Roof Floors Generally Radian prefers a robust floor construction and in the examples either a solid floor or a block and beam construction with a screed covering are used. 1. Solid Concrete floors 60mm of PU foam insulation (floor board) with 70mm of screed, using edge insulation will give a U value of Increasing the insulation to 120mm will give a U value of 0.15 and 170mm of insulation will give a U= 0.11 floor 2. Beam and block flooring systems Flooring systems such as the Rackham Premium Plus can deliver a U= 0.11 floor and go as low as U= 0.08 using polystyrene infill in a beam and block floor Details from 30

31 Appendix Three Construction Roofs 1. Pitched roof insulated at joist level 300mm of mineral wool above and between joists will give a U value of An increase to 400mm of mineral wool will give a U value of Pitched roof insulated at rafter 150mm of mineral wool between rafters with 90mm of PU foam board will give a U value of in a typical warm roof construction. 150mm PU foam between the rafters plus 100mm foam board will reduce the U value to 0.11 The figure above from the Kingspan website gives details on how to achieve reducing U value for a timber deck roof. Further details can be found at 3. Flat roofs 31

32 Appendix Three Construction Walls In general Radian would like to move away from timber frame construction for a variety of reasons, the most significant being fire risk on the construction site. Masonry construction will provide more thermal mass, which can help regulate internal temperatures and help with overheating. As well as traditional cavity wall construction Radian is interested in looking at other options such as Ziegle Block, Thin Joint and solid wall constructions. 1. Cavity Wall A cavity wall construction with a 0.28 U value is achievable with a traditional approach. To achieve higher U values then wider walls are inevitable with a cavity wall construction. 32

33 Appendix Three Construction The above details are from The Concrete Centre Document Energy and CO2- Achieving Targets with concrete and masonry and show a range of options to achieve wall U values from 0.28 to 0.15 using a range of insulation materials. 2. Thin Joint The use of thin joint and large format blocks can have a significant impact on build times. A pre mixed mortar is specially formulated and easily applied and gives a full bond which can help with air tightness. It is also a winter grade mortar which allows construction to continue in the colder months. When calculating U values, the heat loss through the mortar joints is taken into account. Using thin joint can reduce heat loss by minimising the relative area of mortar per m 2 of a wall by roughly 0.01W/m 2 K. 3. ThermoPlan Ziegle Block The Themoplan system is a thin bed insulated structural wall system which can be rendered or clad with stone, brick or timber. The mortar bed follows the princiapals of thin joint and is applied by roller, which allows for a faster build and the system is suitable for low rise buildings up to 4 stories. The system is approved by Zurich Insu ran ce and is considered a Modern Method of Construction (MMC) The following extract shows the U values which are achievable using Ziegle Block Further details can be found at 4. Solid Wall construction The Concrete Centre Document Energy and CO2- Achieving Targets with concrete and masonry also provide 33

34 Appendix Three Construction details on achieving a range of U values using solid wall constructions to achieve a range of U value from 0.28 to Solid wall constructions can also help with air tightness 34