EPC rating explained

An EPC (Energy Performance Certificate) rates your home's energy efficiency on a scale from A (most efficient) to G (least efficient). It also gives a score from 1 to 100. Most UK homes are rated D or E. The certificate is valid for 10 years and is required when you sell or rent your home.

To qualify for the Boiler Upgrade Scheme (BUS) grant, your EPC must be dated within the last 10 years and must not contain an outstanding recommendation for loft or cavity wall insulation (unless that insulation has since been done, or has been assessed as technically unsuitable). A poor EPC rating does not disqualify you, but unresolved insulation recommendations do.

Yes. Adding solar panels typically improves your EPC score by 10–20 points and can move a D-rated home to a C. The EPC calculation considers both expected energy costs and CO₂ emissions — solar PV directly reduces both. A heat pump usually has an even bigger positive impact on EPC than solar alone.

For the ECO4 scheme, properties generally need to be rated D, E, F or G to qualify (EPC C or above is typically excluded). The Great British Insulation Scheme (GBIS) also requires an EPC of D or below for most properties. If your home has a good EPC, you may not qualify for free insulation under these schemes — but you can still benefit from the Boiler Upgrade Scheme.

You need a Domestic Energy Assessor (DEA) to visit your home and produce a new EPC. You can find accredited assessors at the government's EPC register. The cost is typically £60–£120. An assessor will check insulation, heating system, windows, and other factors that affect your home's energy efficiency.

SAP (Standard Assessment Procedure) is the underlying calculation method used to produce EPCs. Your SAP score (0–100+) translates to an EPC band. SAP considers factors like insulation, heating efficiency, renewable energy generation, and glazing. An EPC is the certificate produced from the SAP assessment. You may see SAP referred to in planning or building regulations documents.