EPC Heat Pump Calculator

No. The EPC band is the Energy Efficiency Rating, which is based on modelled running COST per m² per year, not carbon. Electricity costs roughly 3.5× gas per unit (Ofgem cap ~26.11p vs ~7.33p/kWh), and a typical air-source heat pump achieves a seasonal efficiency (SCOP) of only about 2.8–3.0. So the cost of useful heat from a heat pump is similar to, or higher than, a modern condensing gas boiler. Replacing an efficient gas boiler with a heat pump therefore often gives no band improvement and can lower the rating. Switching from oil, LPG, direct-electric heating or storage heaters — all more expensive or less efficient per useful kWh — is more likely to raise the band.

Band C requires a SAP score of 69 or above (band C covers SAP 69–80). Under the government Warm Homes Plan published on 21 January 2026, privately rented homes in England and Wales must reach EPC C by 1 October 2030 (raised from the current minimum of E), subject to a cost cap of £10,000 per property and a set of exemptions. A heat pump alone may not get a gas-heated home to band C; insulation and solar PV are usually needed too.

Not for the band shown on the certificate. SAP 10 cut the electricity carbon factor from 0.519 to 0.136 kgCO₂/kWh, but that improves the separate Environmental Impact Rating (the carbon score), not the cost-based Energy Efficiency Rating that sets the A–G band. Because the electricity-to-gas price ratio is unchanged, a heat pump still scores similarly to, or below, an efficient gas boiler on the EER. From the second half of 2027 a new-style EPC based on the Home Energy Model is being phased in, replacing the single headline rating with four separate metrics — fabric performance, heating-system efficiency, smart readiness and estimated energy cost — and the legacy A–G cost-based rating is expected to continue alongside it until around October 2029. Reporting heating-system performance separately is expected to treat heat pumps more favourably than today.

Yes — and for gas-heated homes the fabric measures usually do the heavy lifting on the EER, because the heating change alone is roughly cost-neutral. Insulation and glazing cut the modelled heat demand and cost, and solar PV cuts modelled electricity cost. For example, on an old non-condensing gas boiler: heat pump (≈0 SAP) + cavity wall insulation (≈+8) + solar PV (≈+8) ≈ +16 points. The Boiler Upgrade Scheme grant of £7,500 (ASHP or GSHP, until March 2030) helps with the heat-pump cost regardless of the EPC effect.

The figures here are indicative heuristics, not a SAP/RdSAP result. The actual change depends on the specific property, so only a qualified domestic energy assessor running RdSAP can confirm the band. The key factors are property age, size, fabric insulation, heating system efficiency, and any renewable technologies installed. Always get a SAP/RdSAP assessment before relying on a predicted band for MEES compliance or a sale.