Heat pump running cost for a 5+ bedroom detached house
A 5+ bedroom detached house uses roughly 24,000 kWh of heat a year. At the current Ofgem price cap an air source heat pump (SCOP 3.5) would cost about £1,790/yr to run, versus about £2,061/yr for mains gas. That is roughly £270 saved a year. A typical ~12kW system costs about £15,500, or £8,000 after the £7,500 grant, paying back in about 29.6 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
£270/yr
13% cheaper to run · ~12kW system
- Now: mains gas heating
- £2,061/yr
- Heat pump running cost
- £1,790/yr
- Gas standing charge saved
- £106/yr
- Install after grant
- £8,000
- Payback time
- 29.6 years
- CO₂ saved
- 3,461 kg/yr
Estimate only. Real figures depend on your home, install and tariff. Prices: Ofgem cap, Jul-Sep 2026.