12 kW Ground Source Heat Pump running cost — All-day heating (18 h)
A 12 kW Ground Source Heat Pump (COP 3.5, BEIS data) draws 3.43 kW of electricity per hour. Running 18 hours/day uses 61.7 kWh and costs £16.11/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Ground Source Heat Pump — All-day heating (18 h): 12 kW ÷ COP 3.5 = 3.43 kW electricity draw × 18 h = 61.7 kWh/day = £16.11/day. Weekly: £112.80. Annual: £5881.46. Context: UK winter, poor insulation or large detached home. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £16.11
- Per week
- £112.80
- Per month
- £490.12
- Per year
- £5881.46
System specification
- Heat output
- 12 kW
- Type
- Ground-source (GSHP)
- Seasonal COP
- 3.5
- Electricity draw
- 3.43 kW/h
- Daily kWh
- 61.7 kWh
- Scenario
- 18 h/day
BEIS Heat Pump Information Note 2024 — 12 kW GSHP, typical SCOP 3.5
How the cost is worked out
- Electricity draw per hour: 12 kW ÷ COP 3.5 = 3.43 kW.
- Daily kWh: 3.43 kW × 18 h = 61.7 kWh.
- Daily cost: 61.7 kWh × 26.11p/kWh = £16.11.
- Weekly: £16.11 × 7 = £112.80.
- Annual: £16.11 × 365 = £5881.46.
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COP 3.5 from DESNZ/BEIS — Heat Pump Information Note: Seasonal Performance Data 2024 (OGL v3.0). Unit rate 26.11p/kWh from Ofgem — Energy price cap unit rates and standing charges (1 July to 30 September 2026).