Heat pump running cost for a 5+ bedroom semi-detached
A 5+ bedroom semi-detached uses roughly 20,000 kWh of heat a year. At the current Ofgem price cap an air source heat pump (SCOP 3.5) would cost about £1,492/yr to run, versus about £1,735/yr for mains gas. That is roughly £243 saved a year. A typical ~10kW system costs about £14,000, or £6,500 after the £7,500 grant, paying back in about 26.8 years.
Your standard rate. The tariff scenario is shown separately.
Efficiency. 3.5 is typical.
On a standard tariff (price cap)
electricity at 26.11p/kWh
£243 /yr saved
Heat pump £1,492/yr · payback 26.8 yrs
On a heat pump tariff (~15p/kWh)
cheap-rate electricity
£878 /yr saved
Heat pump £857/yr · payback 7.4 yrs
Heat pump tariffs (Octopus Cosy, EDF, Scottish Power) offered off-peak rates of about 14p to 15p/kWh in June 2026. The ~15p scenario assumes most heating runs in the cheap hours.
- Now: mains gas heating
- £1,735/yr
- Gas standing charge saved
- £106/yr
- Heat pump electricity use
- 5,714 kWh/yr (~476/month)
- Indicative system size
- ~10kW
- Install after grant
- £6,500
- CO₂ saved
- 2,884 kg/yr
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Estimate only. Real figures depend on your home, install and tariff. Prices: Ofgem cap, Jul-Sep 2026.
What a 5+ bedroom semi-detached house costs to run in each UK region
Same home, same heat pump (SCOP 3.5), priced at each supply region’s Ofgem cap for Jul-Sep 2026, cheapest first.
| Region | Electricity p/kWh | Heat pump £/yr | Gas boiler £/yr | Saving/yr |
|---|---|---|---|---|
| East Midlands (Nottingham, Leicester) | 25.10 | £1,434 | £1,704 | £269 |
| North East (Newcastle) | 25.22 | £1,441 | £1,724 | £283 |
| Yorkshire (Leeds, Sheffield) | 25.31 | £1,446 | £1,722 | £275 |
| West Midlands (Birmingham) | 25.33 | £1,447 | £1,722 | £274 |
| Scotland: south (Glasgow, Edinburgh) | 25.85 | £1,477 | £1,713 | £236 |
| North West (Manchester) | 26.13 | £1,493 | £1,715 | £222 |
| Wales: south (Cardiff, Swansea) | 26.33 | £1,505 | £1,755 | £250 |
| London | 26.35 | £1,506 | £1,773 | £267 |
| East Anglia & Eastern England | 26.38 | £1,507 | £1,719 | £212 |
| South West (Bristol, Devon, Cornwall) | 26.39 | £1,508 | £1,768 | £260 |
| Scotland: north (Aberdeen, Highlands) | 26.42 | £1,510 | £1,713 | £203 |
| Hampshire & Southern England | 26.42 | £1,510 | £1,779 | £270 |
| South East (Kent, Sussex, Surrey) | 26.67 | £1,524 | £1,748 | £224 |
| Merseyside & North Wales (Liverpool) | 27.66 | £1,581 | £1,724 | £143 |
The tariff you are on matters more than the house
Every figure above uses the 26.11p/kWh price cap. A dedicated heat pump tariff runs nearer 15p in its cheap windows, roughly 43 percent off the unit rate, which moves the running cost further than any change to the property itself.