Scottish Energy Performance Certificates - new metrics: research

Footnotes

1 The term useful energy is used throughout this report, but a less technical name is likely to be used if this comes into public use.

2 Chapter 8 Developing a Regulatory Framework for Zero Emissions Buildings - Heat in Buildings Strategy - achieving net zero emissions in Scotland's buildings - gov.scot (www.gov.scot)

3 SAP and RdSAP are methodologies used for estimating the energy performance of dwellings in the UK – see here for details. For details see SAP 10.2 - 21-04-2022.pdf (bregroup.com).

4 In very rare cases it can exceed 100 if on-site renewable generation is used.

5 It might be possible to undertake a project to reopen all existing EPCs in the registry using new SAP software and add FEE to the XML. This would be a big undertaking, however.

6 This takes into consideration all the system losses (e.g. pipework distribution losses and hot water cylinder standing losses), to represent the heat load on the heat generator.

7 10% of homes in the SHCS were excluded from the analysis due to problems processing the data into the format required. The excluded cases did not appear to be clustered in such a way as would systematically change the proportions.

8 HTC = Heat Transfer Coefficient; HLP = Heat Loss Parameter, DFEE = Dwelling Fabric Energy Efficiency; UE/m² = Useful Energy per m², where UE includes space heating/cooling, water heating, pumps and fans, and lighting energy.

9 The UE/m² level at which this levelling off occurs is also dependant on the water heating energy, which will be giving a roughly constant floor level of energy use of around 40 kWh/m² per year.

10 Using the alternative UE metric (excluding water heating energy) the equivalent value is 120 kWh/yr/m².

11 A database containing energy performance related data for products used in SAP assessments is available here: Building Energy Performance Assessment - Support Website :Product Characteristics Database (PCDB) (ncm-pcdb.org.uk)

12 This is because in practice such a heat pump would have to run 24 hours per day in order to provide sufficient heat for much of the heating season.

13 Uninsulated cavity walls, no loft insulation, no floor insulation, old double glazing.

14 Insulated cavity walls, 270mm loft insulation, still no floor insulation, post-2012 double glazing.

15 RdSAP 2012 improvement measure logic was used because RdSAP 10 is not yet available.

16 “Mapping options for new EPC metric 31-01-2023.xlsx”