How To Calculate The National Calculation Methodology

Transcription

1 Building Standards Division Building Research Establishment Scottish building regulations - Assessing the impact of changes to the UK NCM on emissions targets proposed within the 2015 energy standards Final Report 18 September 2014

2 Report prepared by: Steven Scott, Eleftheria Maravelaki and Fraser Walsh Directorate for the Built Environment Building Standards Division Denholm House Almondvale Business Park Livingston EH54 6GA Paul Davidson, Brian Anderson and Christine Pout BRE, Garston, Watford WD25 9XX The opinions expressed in this report are those of the authors. Report commissioned by: Directorate for the Built Environment Building Standards Division Denholm House Almondvale Business Park Livingston EH54 6GA Tel: Fax: web: Crown Copyright 2014 Applications for reproduction of any part of this publication should be addressed to: BSD, Directorate for the Built Environment, Denholm House, Almondvale Business Park, Livingston, EH54 6GA This report is published electronically to limit the use of paper, but photocopies will be provided on request to Building Standards Division.

3 Index Glossary... 2 Executive Summary Introduction TER specification (guidance to standard 6.1) Changes to the calculation methodology (fuel carbon factors) Changes to the calculation methodology (scope/algorithms) Conclusions... 9 Annex A - Research supporting the 2015 review Annex B target setting specifications Annex C - Carbon factor changes 2009 to Annex D - Changes in SAP 2012 (BRE, August 2014) Annex E - Changes in SBEM v5.2 (BRE, August 2014)

4 Glossary BER BRE CH 4 CHP CO 2 CO 2 e DER FF Building Emission Rate of a proposed new non-domestic building Building Research Establishment Methane, one of the six gases identified as contributing to climate change Combine Heat and Power Carbon Dioxide, one of the six gasses identified as contributing to climate change Carbon Dioxide Equivalent, describes GHG emissions associated with fuel use within the NCM which now include carbon dioxide, methane & nitrous oxide. Dwelling Emission Rate of a proposed new dwelling building Frame Factor, proportion of window area which is glazing. g-value Solar heat gain coefficient of glazing (expressed as a value between 0 and 1) GHG LPG N 2 O NCM PV Greenhouse Gases, emissions of which are considered to contribute to climate change Liquefied Petroleum Gas Nitrous Oxide, one of the six gases identified as contributing to climate change National Calculation Methodology Photovoltaic SEDBUK Seasonal Efficiency of Domestic Boilers in the UK see SEER SFP SPF TER U-value Seasonal Energy Efficiency Rating Specific Fan Power Seasonal Performance Factor Target Emission Rate for a proposed new dwelling or non-domestic building Heat loss through a material or construction (measured in watts per square metre per degree kelvin, W/m K) 2

5 Executive Summary In January 2013, the Scottish Government issued consultation proposals for a review of energy standards and an aggregate 21% reduction in emissions from new homes and an aggregate 43% reduction in emissions from new non-domestic buildings. Consultation proposals were developed using the edition of the NCM current at the time (SAP 2009 and SBEM v4.1). Industry asked that implications of the new edition of the NCM (SAP 2012 & SBEM v5.2) on proposed targets be considered before finalising proposals for October This document reports on this issue and considers three areas of this change: the new Target Emission Rate (TER) specifications which will be provided in guidance to standard 6.1 (section 2). changes to the calculation methodology - fuel carbon factors (section 3). changes to the calculation methodology - scope/algorithms (section 4). The new TER specifications are intended to deliver improvement and therefore will drive new solutions and approaches to compliance with building regulations. There are specific implications arising from this change and these are explained in brief. Revised standards and guidance for new buildings from October 2015 will be introduced principally as consulted upon. Of the changes introduced by the new edition of SAP and SBEM, changes to the carbon factors of fuels are the element likely to most influence design decisions. This will be most marked where more than one fuel is used and can result in a positive or negative effect dependent upon the fuels and solutions employed. Other changes within the scope or calculation processes of the NCM are not likely to have a significant impact on solutions considered and implemented, though there are some specific areas where a small change may be anticipated. Changes within the NCM are generally moderated as the same process is applied to both the notional and the actual building calculations. On the basis of findings, no action to revise of the 2015 target setting specification is identified - the combined effect of the NCM changes do not result in the specification more onerous than presented during the 2013 consultation on energy standards. To assist awareness of how methodology changes may influence solutions post- October 2015, it is recommended that a note is published summarising the key points of this report. 3

6 1 Introduction 1.1 In January 2013, the Scottish Government issued consultation proposals for a review of energy standards. These included proposals for an aggregate 21% reduction in emissions from new homes and an aggregate 43% reduction in emissions from new non-domestic buildings. Consultation proposals were developed using the edition of the NCM current at the time (SAP 2009 and SBEM v4.1). One of the requests made by industry was that the implications of the new edition of the NCM (SAP 2012 & SBEM v5.2) on proposed targets be considered before finalising proposals for October This document reports on this issue. 1.2 In considering the potential impact of the move to the new editions of the National Calculation Methodology (NCM) on both reported emissions in target setting (Target Emissions Rate - TER) and on the solutions adopted by developers, the following elements are identified as having relevance: a) The TER specification provided in guidance to standard 6.1. This identifies the components used in calculation of the emissions target. The specification is set by the Scottish Government. See section 2. b) Changes to the calculation methodology (fuel carbon factors). This affects reported emissions and therefore the contribution of any fuel element towards an overall emissions rating. Carbon Factors are set by the UK government. See section 3. c) Changes to the calculation methodology (scope/algorithms). This affects calculated energy demand for any given building specification and will subsequently also influence the overall emissions rating. These changes introduced by the NCM contractor (BRE) on instruction of the UK government. See section Work on this report undertaken by officials within Building Standards Division provides initial analysis on items (a) and (b) above. Work on this report undertaken by the Building Research Establishment, as current NCM contractor, addresses item (c) above whilst also offering further commentary on the BSD analysis. 1.4 This report does not seek to re-quantify carbon impact or development cost through example as this will depend primarily on solutions employed. It is instead an overview assessment and commentary on the impact of NCM changes 1. This illustration should assist developers in considering how the revised emissions targets within the 2015 regulations may influence design choices. However, this paper does not discuss changes in the availability or cost of specific elements or solutions for new buildings since consultation, except in 1 Any implications identified will be fed into the cost/benefit analysis within the final Business and Regulatory Impact Assessment for the 2015 changes to standards and guidance. However, reassessment and presentation of abatement in the light of the revised NCM will be determined separately. 4

7 the most general terms. It is considered that such changes, on an ongoing basis, will influence on design choices made by developers in response to the 2015 standards but that this is an aspect of the procurement of new buildings that sits independent of this analysis and of changes to the NCM. Research papers published in support of the 2015 standards are listed in Annex A. 1.5 This report identifies any need to consider further review of target setting specification within consultation proposals in the light of NCM changes. This is based upon the need to identify if resulting legislation and supporting guidance will remain no more onerous than as proposed within the 2013 consultation document. 1.6 An illustration of the target setting specifications for new dwellings and new non-domestic buildings is attached as Annex B. A summary of changes in carbon factors between the current and proposed editions of the NCM is attached as Annex C. 2 TER specification (guidance to standard 6.1) 2.1 New Dwellings The method of setting targets, defined by the proposed primary heating fuel remain broadly as applied in the 2010 standards with five fuel packages specified in the table to clause A low carbon equipment element, where present in packages, is now represented by photovoltaic panels, replacing previous use of solar thermal hot water, as a more universally applicable element. 2.2 The low carbon equipment element is present only in the three fossil fuel packages mains natural gas, LPG and oil. It is omitted in the electricity and biomass fuel packages in recognition of these both already including a low carbon equipment element (heat pump and biomass boiler respectively) and in recognition of the continued importance of such fuels to development in remote and rural areas. 2.3 New non-domestic buildings 2010 standards compare the proposed building against a target set using mains natural gas as the primary heating fuel (or oil where mains gas was not available). Aside from a move to a concurrent notional building specification (as opposed to a 2002 notional building which is then subject to an improvement factor), the main change for 2015 is that the same fuels are used in both notional building (TER) and actual building (BER). This supports the options for delivery of an energy efficient building more consistently across all fuel types. 2.4 Commentary on interaction of NCM with TER specification The proposed building form is defined within the applicant s chosen SAP, SBEM or DSM tool and the values set out in the TER specification are assigned to that building model. This provides a calculation of overall building 5

8 energy demand which is used to calculate both primary energy demand and CO 2 emissions for the Target Emission Rating. It is noted that changes in carbon factors used within the new editions of the NCM will affect reported emissions and this is discussed in the next section. In terms of the calculation of energy demand, the new edition of the NCM does introduce smaller changes to the calculation of auxiliary energy for fans and pumps and the calculation of energy use for lighting. The change in auxiliary energy will in all cases be small and, depending on the particular HVAC system installed in the Actual building could vary in either direction. For lighting, the difference will again be very small and, depending on the geometry of the spaces being modelled, could move in either direction. 3 Changes to the calculation methodology (fuel carbon factors) 3.1 The UK NCM now uses carbon factors which are CO 2 equivalent (CO 2 e) which consider CO 2, CH 4 and N 2 O emissions and their effect on the environment. The paper setting out how revised factors were calculated is published on the BRE SAP 2012 website. 3.2 As stated in section 2, an element of on-site electricity generation is now present in the majority of target setting specifications (3 out of five domestic and both non-domestic specifications). It is anticipated that a change in the relationship between the carbon factor of electricity as a fuel and the carbon factors of other fuels will have the most noticeable effect on the choice of solutions implemented. 3.3 Comparative carbon factors are noted in Annex B. The table below shows how the five fuels commonly associated with domestic development have changed to be either more or less carbon intensive. Table 1 changes in carbon factors of common fuels for dwelling example. Fuel Emissions (kg.co 2 /kwh) % increase Mains gas Bulk LPG Oil (domestic) Fuel oil wood pellets (bulk) standard tariff Electricity Electricity displaced from grid What this means in practice is that where a designer is considering solutions to meeting the Target Emission rates set in guidance to standard 6.1, the relative efficacy of those solutions will differ from what they were under the 2009 editions. 6

9 3.5 The significance of this variation will depend on three main factors a) The positive or negative effect of the change in carbon factor of the fuels used; b) The extent to which a proposed solution deviates from the specification used to set the Target Emissions rating; and c) The relative carbon intensity of the fuels in question where either a lower carbon fuel is used to mitigate the BER/DER; or where generation of heat or power is applied to offset emissions arising from energy demand. 3.6 Efficacy of on-site electricity generation in offsetting energy demand In the new edition, onsite generation of electricity is slightly less effective in offsetting energy demand from mains gas, oil or biomass and remains almost the same where LPG is a heating fuel. The carbon factor for electricity as a fuel has increased only marginally (0.4%) compared to those other fuels (9.1%, 8.8%, 39.3%). The carbon factor of biomass, although almost 40% higher, remains very low in comparison to fossil fuels and to electricity. Accordingly, this change in carbon factor will have little impact on the proportion of overall emissions in an offsetting scenario. 3.7 New Dwellings New house heated by mains natural gas. TER is calculated using an element of PV. Where designers choose to broadly follow the TER approach (broad balance between fabric and service efficiency with low carbon component) - no impact in terms of solution needed though reported emissions (both TER and DER) will be higher. Where designers choose a stronger fabric first approach or more effective controls (reduces demand for heating fuelled by mains gas) demand reduction becomes more effective than offsetting due to greater increase in carbon factor for mains gas than for electricity. Where the designer chooses a larger Low Carbon Equipment (LCE) element such as a larger PV array and poorer fabric, offsetting is less effective for the same reason. 3.9 New Non-domestic buildings For a new non-domestic building, the main changes that will affect specification relate to how emissions targets are set in the notional building specification. The move from the 2002 notional building, with improvement factor, and use of gas/oil as heating fuel, to the 2015 concurrent notional building where the same heating fuel is used for both notional and actual building. In addition to those provisions, the impact of carbon factors within the NCM will be broadly similar to that described in paragraph 3.7 for new dwellings. 7

10 4 Changes to the calculation methodology (scope/algorithms) 4.1 Domestic Published changes to SAP within the new 2012 Edition are noted as follows: climatic data has been extended to allow calculations using regional weather (not used in compliance calculation). an allowance for height above sea level is incorporated into external temperature data. CO 2 emission factors have been extensively revised (per section 3 above). fuel price and primary energy factors have been revised (not used in compliance calculation). the options for heat losses from primary pipework have been extended. 4.2 In more detail, changes within the methodology that have an impact on the calculated energy performance are as follows (see Annex D): The effect of including height above sea level increases the energy needed for space heating (by 1-2% for both DER/TER calculations). Thermal bypass must be considered in relation to walls separating any heated spaces. Weather compensators for condensing boilers must be present in the product characteristics database and may be restricted as to boilers they can operate with. Efficiency enhancements for condensing boilers and heat pumps are applicable if the system is specifically designed for low temperature operation. Less electricity is included for new circulation pumps; impact minor. Primary pipework losses are reduced slightly, different impact on stored hot water and combi boilers as options. The contribution from solar water heating is reduced if the only shower type present is electric. 4.3 Non-domestic Published changes to the ND NCM within the new Edition are noted as follows: A new set of fuel emission factors (per section 3 above) and primary energy factors. Enhanced methodology for modelling PVs. Enhanced methodology for modelling movable window shading devices. Facility for modelling non-transpired solar collectors. Modified methodology for calculating auxiliary energy for fans and pumps. 8

11 Modified approach to calculating the energy consumption for general lighting in the notional building, based on luminous efficacy values and the geometry of each zone Facility to carry out Green Deal analysis (not used in compliance calculation) Range of purposes of analyses available (not used in compliance calculation) 4.4 Aside from the effect of revised carbon factors for fuels, changes within the methodology will have an impact on calculated energy performance (see Annex E). In general terms, these can be summarised as follows: The only changes to affect the TER are those related to auxiliary energy and lighting. In all cases the changes are very small, but could vary in either direction depending on geometry and particular HVAC systems. However, the same changes are also applied to the BER. The changes for PV panels and shading devices will only affect the Actual building calculation. Such changes to the BER are small, though could be in either direction depending on the simplifying assumptions made when using the previous version of the NCM. The new facility to model a nontranspired solar collector was not available in the previous version. 5 Conclusions 5.1 Key points noted Changes within the domestic and non-domestic methodologies calculating energy demand for new buildings will result in minor changes to calculated energy for space and water heating, with minor to moderate changes in energy demand from auxiliary systems and minor changes to lighting in non-domestic buildings). The scale of these effects will be less than the impact of uncertainties in some of the other parameters in the calculation. They could introduce either an increase or decrease in calculated absolute energy consumption, depending on the particular geometry and systems involved. Because of the complex interactions involved, no generic guidance can be provided. In any given circumstance, the effect of different design choices can only be determined by modelling different options a process which the calculation tools make very easy. For domestic, installation certificates have been introduced for the following: o installation certificate for MCS installed heat pumps o design, installation and commissioning certificate for low temperature heating systems o inspection checklist for mechanical ventilation systems 9

12 o installation checklist and certificate for waste water heat recovery systems Changes in carbon factors will result in different emissions targets for new buildings than under the 2009 edition of the NCM. The impact of this in terms of design solutions is mitigated to a great extent by the application, in target setting, of the same primary heating fuel source(s) to both target setting (TER) within the notional building and the compliance calculation for the proposed building (BER/DER). The impact of revised emission factors, albeit small, will be most evident in solutions which depart more significantly from the specification used to set emissions targets, primarily where solutions introduce or omit elements present in target setting, such as use of more than one fuel source or through on-site generation. There will be small increase in the generation capacity needed to offset demand from some fossil fuels. In isolation this might favour a more traditional fabric and services approach but developers will also take into account cost of and simplicity of solutions so any direct impact, however small, is not certain Observations Designers may, subject to meeting backstops in guidance to standards , still propose solutions which meet the TER in any way they deem appropriate through the NCM calculation. The flexibility inherent in this approach enables the widest possible range of solutions to a particular development. This is a feature of the use of functional standards and a holistic approach to energy design within Scottish building regulations. 5.3 Conclusion On that basis, no action to revise of the 2015 target setting specification is identified as the combined effect of the NCM changes do not result in the specification presented during the 2013 consultation being more onerous to deliver. In some cases, as illustrated by the fabric first example in paragraph 3.7, the new edition of the NCM may favour a design approach which emphasises demand reduction over offsetting. 5.4 Recommendation Designers would benefit from being aware of how changes may influence the design solutions proposed and adopted after October It is therefore recommended that a note summarising the key points of this paper is published to accompany the implementation of revised Technical Handbooks. 2 For example, from most recent published data, cost of PV arrays continues to reduce in line with predictions made in Solar PV cost update (Department of Energy & Climate Change, May 2012). 10

13 Annex A - Research supporting the 2015 review Non-Domestic Buildings - Investigating aspects of the calculation methodology for the proposed 2013 standards for new non-domestic buildings: Phase 3 Final Report Contractor: AECOM Project Year 2012/13 This project investigates variations on the notional building specification of within 2013 Phase 2 research and their cost impact, together with commentary on credits available within the NCM and potential for assessment of overheating. Non-domestic energy standards 2013: Investigating improved CO 2 emission and energy targets for new non-domestic buildings compared to 2010 standards: Phase 2 Final report Contractor: AECOM Project Year 2011/12 This project informed the process of setting minimum carbon dioxide and energy standards for new-build non-domestic buildings from It investigated the application of absolute values for energy efficiency and an aggregate approach to setting CO2 emissions across a range of nine building examples. It also provides an assessment of the national impact of a range of improvement levels. Domestic Buildings - Cost Impact of potential improvements to energy standards for new domestic buildings: Phase 2 Final report Contractor: Building Research Establishment Project Year 2011/12 This research provided a comprehensive assessment of the potential technical and cost implications of improvements to energy standards in building regulations. It provides further analysis of the six example dwellings used in the Phase 1 research as well as detail on a further eight dwelling types. Domestic Research - Research to further assess the difference in capital costs of constructing a gas and electricity fuelled dwelling: Phase 1 Addendum Final report Contractor: Gleeds Cost Management Ltd Project Year 2011/12 This research concentrated on the cost difference of compliance with the building standards using gas or electricity as the main dwelling fuel. The study provides data to inform discussions on the impact on development in areas where mains gas is not available such as more remote and rural areas. Domestic Buildings - Feasibility of further reductions in CO 2 arising from regulated energy use in new homes: Phase 1 Final report Contractor: Gleeds Cost Management Ltd Project Year 2010/11 Using a range of six example dwelling types this research investigated the technical and commercial feasibility of further reductions in carbon dioxide emissions arising from regulated energy use in new homes. Non-Domestic Buildings - Cost impact of potential improvements to energy standards for new buildings within building regulations: Phase 1 Final report Contractor: Davis Langdon Project Year 2010/11 This project identified the cost and practicality of further improvements in the carbon dioxide emissions standard (6.1) by development of a range of example buildings, showing cost-effective solutions to both the 2009 and 2010 building standards and to three specified further levels of improvement. 11

14 Annex B target setting specifications Domestic target setting. Commentary method of setting targets based upon primary heating fuel remain broadly as applied in the 2010 standards. A low carbon equipment element, where present in packages, is now represented by photovoltaic panels, replacing previous use of solar thermal hot water as a more universally applicable element. The measures identified in this table are set to delivery, on aggregate, 45% fewer carbon dioxide emissions than the 2007 standards. Whilst it is possible to construct a dwelling using one of the packages of measures (see clause 6.1.6), this table is provided for the purpose of setting the target emission rate (TER) for the notional dwelling. Main space heating system fuel [1] [2] [3] Element or System Gas (Package 1) LPG (Package 2) Oil (Package 3) Electricity (Package 4) Biomass [4] (Package 5) Walls U = 0.17 U = 0.17 U = 0.17 U = 0.17 U = 0.17 Floors U = 0.15 U = 0.15 U = 0.15 U = 0.15 U = 0.15 Roofs U = 0.11 U = 0.11 U = 0.11 U = 0.11 U = 0.11 Openings [5] U = 1.4 U = 1.4 U = 1.4 U = 1.4 U = 1.4 Allowance for thermal bridging [6] 0.08 x total exposed surface area 0.08 x total exposed surface area 0.08 x total exposed surface area 0.08 x total exposed surface area 0.08 x total exposed surface area Open flues None One One None One Heating system, pump in heated space [7] Gas boiler room-sealed fan flued 89% efficiency LPG boiler room-sealed fan flued 89% efficiency Oil boiler room-sealed fan flued 90% efficiency Air to water heat pump 175.1% efficiency [8] Wood pellet boiler 86% efficiency, HETAS approved Heating system controls Hot water (HW) system (not applicable if combi-boiler) Secondary space heating Heat recovery systems Time and temperature zone control + Boiler interlock + weather compensation + delayed start Stored HW (from boiler) separate time control for space and water heating none Instantaneous waste water heat recovery system 45% efficiency Time and temperature zone control + Boiler interlock + weather compensation + delayed start Stored HW (from boiler) separate time control for space and water heating 10 % closed wood logburning room heater [9] Instantaneous waste water heat recovery system 45 % efficiency Time and temperature zone control + Boiler interlock + weather compensation + delayed start Stored HW (from boiler) separate time control for space and water heating 10 % closed wood logburning room heater [9] Instantaneous waste water heat recovery system 45% efficiency Time and temperature zone control Stored HW by air to water heat pump and electric immersion 10% electric none Instantaneous waste water heat recovery system 45% efficiency Photovoltaics Yes [10] Yes [10] Yes [10] No No Time and temperature zone control + + delayed start Stored HW (from boiler) separate time control for space and water heating Instantaneous waste water heat recovery system 45% efficiency 12

15 For the 'notional dwelling' in addition all of the following applies in every fuel type: Windows, doors & rooflights area 25% of total floor area [11] Orientation Shading (glazing) Number of sheltered sides 2 Chimneys Ventilation system Air infiltration (building fabric) Hot water cylinder Primary water heating losses (where applicable) Low energy light fittings Thermal mass parameter Party wall heat loss (applicable to cavity separating walls) Waste water heat recovery unit (WWHR) Notes: all glazing orientated east/west (no roof windows) average overshading None natural ventilation with intermittent extract fans, 4 for dwellings with floor area more than 80 m 2, 3 for smaller dwellings 7 m 3 /h m 2. at 50 Pa 150 litre cylinder insulated with 80 mm of factory applied foam (cylinder in heated space); cylinder temperature controlled by thermostat primary pipework insulated 100% of fixed outlets The value identified for the proposed building should be used 0.0 W/m 2 K 2 assumed in dwellings with floor area more than 100m 2, 1 for smaller dwellings 1. Where a multi-fuel appliance is proposed, assessment of both TER and DER should be based upon the fuel option with the highest carbon factor (e.g. multi-fuel stove capable of burning coal or wood is assessed as solid mineral fuel). 2. Where heat is supplied to a dwelling from more than one source, through a generation mix (e.g. community heating using both oil and biomass where heat is provided from both sources simultaneously), the primary heating element within the TER should be calculated pro rata, on the basis of the identified fuel mix. The same mix should be used in calculation of the DER, including any pro rata contribution made by solutions such as CHP. This does not apply where heat demand can be provided solely from one of the identified generating sources, in which case other identified heat sources should be considered as back-up systems and excluded from assessment. 3. Where solid mineral fuel is proposed for the main space heating system, the TER should be calculated using the values identified for oil as a fuel (package 3). This will require improvements in performance within the DER specification for compliance. 4. The biomass column should be used not only where biomass fuel is to be used but also for biogas, large scale waste combustion from boilers and waste heat from power stations. 5. U is the average U-value of all openings (windows, doors, rooflights) based on one opaque door of area 1.85 m² and U=1.4, any other doors fully glazed. For windows, doors, etc. a frame factor of 0.7, light transmittance of 0.80 and solar energy transmittance of 0.63 are assumed. 6. For the purposes of setting the TER, a y-value of 0.08 is identified. Note: for DER, this element of calculation must use either default y=0.15 or Htb calculated from length of junctions and individual psi values. 7. In the case of gas, LPG and oil, the specified efficiency values for the boiler in the notional dwelling are SEDBUK(2009); distribution temperature 55 C (e.g. radiators as emitters). 13

16 8. Seasonal Performance Factor (SPF) specified for the system includes application of a distribution temperature of 55 C (e.g. radiators as emitters). 9. The closed room heater included within the fuel package table should be capable of burning wood only, not multi-fuel. 10. For purpose of calculating the benefit of the PV element in the TER reduction, region is UK average, orientation SW, pitch 30 and overshading no or little. and kwp is the smaller of: - dwelling total floor area (in m²) x 0.01, and - roof area limit. The roof area limit is to ensure that the PV area does not exceed 30% of the roof area (based on 30 roof pitch and 0.12kWp per m² PV area). In the case of a flat or maisonette the roof area limit is divided by the number of storeys in the block. 11. If total exposed facade area is less than 25% of the floor area, the area of windows, doors and roofs should be taken as the area of the total exposed facade area. Non-domestic target setting. Commentary - Aside from a move to a concurrent notional building specification (as opposed to a 2002 notional building which is then subject to an improvement factor), the main change for 2015 is that the same fuels are used in both notional building (TER) and actual building (BER) standards compare the proposed building against a target set using mains natural gas as the primary heating fuel (or oil where mains gas was not available). The fabric and services specifications of the notional building are assigned on a zone by zone basis, based upon the activity type defined for each zone. There are two specification categories applied on the basis of the daylighting and conditioning strategy assigned to each activity type within the NCM Side-lit, heated only or Side-lit, heated and cooled. The zone by zone approach allows designers to assign the heated and cooled specification only to those zones of an otherwise heated only building where both heating and cooling is required, therefore reducing the overall energy use and carbon dioxide emissions of the building. The following table includes the standard notional building zone specifications for fabric and fixed building services depending on the zone daylighting and conditioning strategy. 14

17 Notional building zones - fabric and fixed building services values Element Zone heated & naturally ventilated Zone heated & mechanically ventilated/ cooled Roof (U-value, W/m 2.K) Wall (U-value, W/m 2.K) Floor (U-value, W/m 2.K) Window (U-value (W/m 2.K) 1.8 (10% FF) 1.6 (10% FF) (g-value, %) 60% 50% (transmittance, %) 71% 71% Roof-light (U-value (W/m 2.K) 1.8 (15% FF) 1.8 (15% FF) (g-value, %) 52% 52% (transmittance, %) 57% 57% Vehicle access and similar large doors Pedestrian doors and high usage entrance doors Thermal capacity of element Refer to NCM Modelling Guide for details Thermal bridging - Junctions Refer to NCM Modelling Guide for details Air-permeability m 3 /m 2.hr [1] 5 3 Lighting Efficiency (Luminaire lumens/ Circuit watt) Occupancy control (Yes/No) Yes Yes Daylight control (Yes/No) Yes Yes Heating and DHW (% efficiency) Fuel(s) for actual building applied to the notional building. Refer to NCM Modelling guide for details. Central Ventilation (SFP, W/l/s) N/A 1.8 Terminal Unit (SFP, W/l/s) N/A 0.4 Cooling (SEER) N/A 4.5 Heat recovery (% efficiency) N/A 70% Variable speed control of fans, pumps and circulators (Y/N including multiple Yes Yes sensors) Photovoltaic Panels (% of floor area) 4.5% 4.5% Notes: 1. In certain buildings, air permeability is further differentiated by building size. Refer to NCM Modelling Guide Environment/Building/Building-standards/techbooks/techhandbooks/ncmg

18 Annex C - Carbon factor changes 2009 to 2012 Source: SAP Table 12, NCM Modelling guide for each edition. Note that less common fuels and those not present in both editions omitted for simplicity. Fuels modelled in SBEM shown in bold. Fuel Gas: 16 Emissions (kg.co 2 /kwh) % increase Mains gas Bulk LPG Bottled LPG Oil: Heating oil (SAP) Fuel oil (SBEM) Biodiesel from any biomass source Biodiesel from used cooking/vegetable oil only appliances able to use mineral oil or liquid biofuel B30K Solid fuel: House coal anthracite manufactured smokeless fuel wood logs wood pellets (in bags for secondary heating) wood pellets (bulk supply for main heating) wood chips dual fuel appliance (mineral and wood) Electricity: standard tariff hour tariff (high rate) hour tariff (low rate) hour tariff (high rate) hour tariff (low rate) hour heating tariff Electricity displaced from grid Community heating schemes: Heat from boilers mains gas Heat from boilers LPG Heat from boilers oil Heat from boilers B30D Heat from boilers coal

19 Fuel Emissions (kg.co 2 /kwh) % increase Heat from electric heat pump Heat from boilers waste combustion Heat from boilers biomass Heat from boilers biogas (landfill/sewage gas) Waste heat from power station Geothermal heat source / Heat from CHP Electricity generated by CHP Electricity for pumping in distribution network

20 Annex D - Changes in SAP 2012 (BRE, August 2014) Climatic data New climatic data was acquired from the Met Office, calculated by interpolation of weather station data throughout the UK and averaged over the period 1992 to Weather data is now defined by postcode giving more local data for applications like Green Deal and ECO as well as cost information on EPCs. Calculations for building regulation compliance and ratings use UK average climatic data irrespective of where the property is situated, as before. It is the climatic data averaged over the East Pennines region but now designated as "UK average". All calculations use external temperature based on the actual readings, rather than being corrected to mean sea level as they were previously. The effect of climate data amendments is to increase the calculated energy needs for heating by about 1-2% for UK average conditions. Emission factors All emission factors (and primary energy factors) were reviewed to take account of the latest information from government sources and more significantly to (a) to use CO 2 - equivalent factors that incorporate the global warming effect of methane and nitrous oxide and (b) to include emissions associated with transportation and also upstream emissions that occur outside the UK (for imported fuels). As a result the factors for most fuels have increased. The factor for electricity is (coincidently) almost unchanged, however, it being affected also by the changing mix of fuels used in the generation of electricity throughout the UK. Other changes Semi-rigid ductwork whose air flow characteristics have been tested can be treated as rigid when used with MVHR systems. Clarification that thermal bypass can occur with unfilled cavity walls between any heated spaces, for example between flats and heated access corridors. Lower efficiency for generic heat pumps, unless installed under MCS. Recognition that the efficiency of condensing boilers and heat pumps are affected by the temperature at which they operate, rather than whether they supply radiators or underfloor heating. Efficiency enhancements are available for low temperature design, rather than according to the heat emitter type. Weather and load compensators for use with condensing boilers can now be used only when located in the product database. This allows BRE to check their efficacy before they can be used in SAP calculations, and it will be possible to adjust the efficiency uplift for specific devices where that is appropriate. 18-hour tariff has been added to the electricity tariff options, specifically for CPSUs. 18

21 Database tables have been added for gas condensing warm air systems and high heat retention storage heaters. This allows due credit to be given to these better performing heating appliances. Provision has been made for a database table containing technical data for community heat networks. This is the start of a process for better assessment of community schemes, which hitherto have been given far less attention than individual heating appliances in dwellings. The methodology includes the treatment of a storage waste water heat recovery system, which enables heat recovery from all bathing water, not only mixer showers (with less overall efficiency as heat is lost from the store). A more detailed treatment of heat loss from solar collectors is included to counter some anomalies that had arisen. Solar hot water systems now have less effect if electric showers are used, and more if electric showers are not used. More data on thermal bridging, which will have the effect of increasing thermal bridges heat loss in some cases like dwellings with roof rooms. Amendments to losses from primary pipework, to take to allow for the extent of pipework insulation and time the pipework is hot. The loss is reduces with separate timing of water heating, and in summer months if there is solar water heating. There is less electricity used by circulation pumps installed in 2013 or later (taking account of Energy Related Products Directive legislation). 19

22 Annex E - Changes in SBEM v5.2 (BRE, August 2014) Emission factors All emission factors (and primary energy factors) were reviewed (under the SAP contract) to take account of the latest information from government sources and more significantly to (a) use CO 2 -equivalent factors that incorporate the global warming effect of methane and nitrous oxide and (b) include emissions associated with transportation and also upstream emissions that occur outside the UK (for imported fuels). As a result the factors for most fuels have increased. The factor for electricity is (coincidently) almost unchanged, however, being affected also by the changing mix of fuels used in the generation of electricity throughout the UK. The effect of these changes on Section 6 compliance is expected to be negligible, given that they apply to both the actual and notional buildings and that the fuel and HVAC strategy in the notional building is matched to the situation in the actual building. However, there is potential for solutions that vary more significantly from the target setting specification to be influenced by changes in these factors. The impact on EPC ratings will be more noticeable, but will depend very largely on the fuel choices. A quick analysis of a typical, existing, shallow-plan office building under various HVAC and fuel scenarios shows a variance in the Building Emission Rate of between zero and an increase of 4.5% (see separate spreadsheet). The largest increases are for a) electric cooling and gas-oil heating (3.1%), b) electric cooling and biomass heating (2.6%) and c) electric cooling and gas-oil heating, with 25% of the electricity supplied by on-site generation (4.5%) The increase for case c) above is because the factor for exported electricity used to be higher than for bought-in electricity but is now the same. This case also has the highest absolute increase in emissions from 36.2 to 37.8 kg.co 2 /m 2 /yr. Except where the previous EPC rating fell just below a band boundary, these small increases will make no difference to the EPC band. Other changes Most other changes to the software apply only where there are particular features present in the modelled building (such as PV panels or transpired solar collectors). Their impact is likely to be small in all case, but the direction and scale of change will depend on the particular circumstances of the building under consideration. The changes to the software are described below. The enhanced methodology for modelling PV systems in v5.2.x allows the calculation of more accurate results for PV output electricity by allowing the user to either input the peak power of the PV array, if known, or select the PV module technology and input the area of the array (which was the only option available in v4.1.e). The new methodology also allows the user to define further specifics regarding any overshading on the PV array and its ventilation strategy. The new PV methodology in v5.2.x could, therefore, have an impact on the amount of CO 2 emissions displaced by 20

23 PV systems in the building and, hence, the emission rate of the building could change in either direction compared to that calculated using v4.1.e. The new methodology in v5.2.x for modelling movable shading devices on windows improves on the limited approach and simplified input options which were in v4.1.e, in order to apply a more accurate calculation of the likely operation of these devices and the resulting solar gains. The user is allowed to define the location of the shading device with respect to the window glazing, as well as the colour and translucency of the shading device. The new window shading methodology in v5.2.x could have an impact on the calculated heating and cooling energy demand calculated in the building, and consequently, the heating, cooling, and auxiliary energy consumption and CO 2 emission rate of the building compared to those calculated in v4.1.e. The change can be in either direction. In addition to transpired solar collectors, SBEM v5.2.x includes the facility to model non-transpired solar collectors. Allowing users to model new technologies, such as these, in SBEM should result in a more accurate representation of the energy performance of their buildings. Including this technology in the model could have an impact on the calculated heating and cooling energy demand calculated in the building, and consequently, the heating, cooling, and auxiliary energy consumption and CO 2 emission rate of the building compared to those calculated in v4.1.e. Changes which existed in SBEM v4.1.e for other countries in the UK and are proposed to be adopted by Scotland in v5.2.x within the notional building methodology Modified approach for calculating the auxiliary energy as the sum of the pump energy and fan energy after they have been calculated separately using a specified method. This could lead to a change in the CO 2 emission rate of the building, in either direction, compared to that calculated in v4.1.e. Modified approach for calculating the energy consumption for general lighting based on a notional luminous efficacy value for the luminaires and the geometry of each zone. This could lead to a change in the CO 2 emission rate of the building, in either direction, compared to that calculated in v4.1.e. 21