What is SAP Appendix Q?

SAP Appendix Q is part of the UK’s system for measuring how energy efficient a home is. This system is called SAP (Standard Assessment Procedure), and it’s used to calculate Energy Performance Certificates (EPCs) for homes. Because SAP is only updated periodically, it cannot always immediately reflect new technologies or innovations. SAP Appendix Q exists to bridge this gap. It allows proven new products to be recognised between SAP updates by using independently verified performance data. Appendix Q acts as a temporary mechanism, ensuring innovative products are not penalised simply because SAP assumptions have not yet caught up.

Why Does SAP Appendix Q Matter And How Does It Work?

Some energy-efficient products use less energy, but standard SAP calculations don’t always reflect this properly. SAP Appendix Q helps by using real performance data, so genuine energy savings are recognised. This supports lower energy bills, reduced carbon emissions and fairer, more accurate energy ratings. In standard SAP calculations, showers are assumed to use at least 8 litres of water per minute. However, air-powered showers typically use much less – around 4.5 litres per minute, while still delivering a satisfy ing shower.  

Appendix Q allows assessors to calculate the reduced hot water and energy use and include this in the SAP assessment before the EPC is produced. This ensures the home’s energy rating more accurately reflects real-life performance. For a product to be included in SAP Appendix Q:

– It must be independently tested

– The tests must prove it performs better than standard options

– The results are reviewed and approved

Approved products are added to the SAP Appendix Q database for assessors to use.

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