Quantifying the spatial variation of the energy performance gap for the existing housing stock in England and Wales

This paper evaluates the energy performance gap between Energy Performance Certificate predictions and annual gas meter reading measurements for the existing housing stock in England and Wales. Energy Performance Certificates predict energy using the SAP model, the UK regulatory tool for existing dwellings widely used in national and local housing energy policies. The results show an energy performance gap of between +16.6% and +17.9% at the national level. Of concern is that the performance gap is shown to vary greatly across different regions of England and Wales (−23.7% to +56.4% for local authorities) and to vary with factors such as built form, construction age and predicted gas consumption. This suggests that there may be structural errors in the EPC/SAP approach resulting in certain spatial areas or dwelling types having more errors in their EPC predictions, impacting on future planning for housing stock retrofits.