Heat pump running cost for a 3-bedroom detached house
A 3-bedroom detached house uses roughly 14,500 kWh of heat a year. At the current Ofgem price cap an air source heat pump (SCOP 3.5) would cost about £1,082/yr to run, versus about £1,287/yr for mains gas. That is roughly £205 saved a year. A typical ~7kW system costs about £12,000, or £4,500 after the £7,500 grant, paying back in about 21.9 years.
Your region (sets local prices)
Property type
Bedrooms
Insulation
Current heating & its price
p/kWh
p/kWh
A heat-pump tariff can be ~13-15p.
Efficiency. 3.5 is typical.
£
A heat pump would cut your heating bill by
£205/yr
16% cheaper to run · ~7kW system
- Now: mains gas heating
- £1,287/yr
- Heat pump running cost
- £1,082/yr
- Gas standing charge saved
- £106/yr
- Install after grant
- £4,500
- Payback time
- 21.9 years
- CO₂ saved
- 2,091 kg/yr
Estimate only. Real figures depend on your home, install and tariff. Prices: Ofgem cap, Jul-Sep 2026.