Heat pump running costs against gas
Figures updated 15 November 2026
At today's price cap, a heat pump with the efficiency the government's field trial measured (a seasonal figure of 2.78) delivers heat for 9.5p per kWh. A gas boiler delivers it for 9.7p. A heat pump beats gas once its seasonal efficiency is above 2.70, or about 2.84 once VAT on electricity returns in April 2027.
| Heating | Per kWh of heat |
|---|---|
| Gas boiler (82% efficient), gas at 8.0p | 9.7p |
| Heat pump (2.78), electricity at 26.3p | 9.5p |
Great Britain average energy price cap, 1 October to 31 December 2026. Boiler efficiency from SAP 10.2. Heat pump efficiency: the median measured in the Electrification of Heat trial, including backup heating and pumps. Sources
What it means for a whole bill
A gas-heated semi in Birmingham pays £1,882 a year for gas and electricity. With a heat pump on Cosy Octopus, which has cheap hours for heating, the bill falls by £144 a year if the gas supply is taken out, or £35 if gas stays for cooking and the standing charge carries on.
A quarter of the heat pumps in the trial reached 3.19 or better, measured at the heat pump. At 3.19 the saving is £246 a year.
Annual figures at electricity prices from April 2027. Heat demand from the median gas use of a semi in England and Wales (DESNZ).
Why a heat pump tariff matters
Cosy Octopus charges its lowest rate 04:00 to 07:00, 13:00 to 16:00, 22:00 to 00:00, every day. The figures above assume the heat pump runs when the house needs heat, not only in those hours. The calculator below picks the cheapest tariff for your home.