Quick answer
Yes, for now. Under today's RdSAP 10 methodology, a well-controlled gas boiler can still contribute to an EPC C rating. But from 1 October 2029, the Home Energy Model (HEM) becomes compulsory, and under its Heating System Metric a gas boiler alone cannot achieve band C - gas-heated properties will need to qualify via the alternative Smart Readiness Metric instead.
How a Gas Boiler Is Scored Today
Under the current RdSAP 10 methodology, your heating system is scored on efficiency (mainheat/mainheatc energy efficiency) and on the controls fitted alongside it - a programmer, room thermostat, and thermostatic radiator valves (TRVs). A modern condensing combi boiler with full heating controls can score well, and combined with reasonable insulation and glazing, many gas-heated properties reach EPC C comfortably today.
Where gas-heated properties fall short is usually elsewhere on the certificate - missing insulation evidence, older glazing, or an untested air tightness default - not the boiler itself.
Why HEM Changes the Picture
From 1 October 2029, the Home Energy Model (HEM) replaces RdSAP 10 as the only permitted EPC methodology. HEM introduces a dual metric standard: a Fabric Performance Metric, plus either a Heating System Metric or a Smart Readiness Metric.
A gas boiler alone cannot achieve band C here, regardless of how efficient or well-controlled it is.
The alternative route - typically solar PV plus a smart meter - can achieve C without touching the boiler.
The Practical Takeaway
If your property currently has gas heating and reaches (or is close to) EPC C, securing that rating under RdSAP 10 before October 2029 locks it in for up to 10 years - before the Heating System Metric rules gas out of band C. Read more in our guide to EPC grandfather rights.
Frequently Asked Questions
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