What does an EPC point cost?

Warm Homes: Local Grant asks local authorities to reach EPC band C where they can, within twin cost caps of £16,600 a home, and to take a value for money and strategic approach to measures where they cannot. The guidance is explicit that there is no fabric first mandate, and that a mixed package such as insulation and solar, or a smart package of solar, controls and battery storage, may achieve higher bill savings for a lower price depending on the home.

That leaves a practical question on every property: which measures buy the most improvement per pound spent here? We are asked it often, and we could not find a published answer, so we worked one out.

The calculation uses Ofgem’s own deemed scores, the SAP modelled annual savings that the ECO4 and Great British Insulation Scheme obligations were scored on, converted into rating points using BRE’s published rating equation. Measure costs are scheme delivery averages from the government’s own statistics. We then ran the same model against 28 of our completed Warm Homes properties and compared it with the RdSAP ratings lodged after the works. Every figure and its source is set out in the method below the calculator.

Nothing here decides eligibility, and nothing here replaces a retrofit assessment. It is a way of comparing measures before the design is commissioned.