12 kW Ground Source Heat Pump running cost — Cold winter day (12 h)
A 12 kW Ground Source Heat Pump (COP 3.5, BEIS data) draws 3.43 kW of electricity per hour. Running 12 hours/day uses 41.1 kWh and costs £10.74/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Ground Source Heat Pump — Cold winter day (12 h): 12 kW ÷ COP 3.5 = 3.43 kW electricity draw × 12 h = 41.1 kWh/day = £10.74/day. Weekly: £75.20. Annual: £3920.98. Context: UK winter (Dec–Feb), outdoor temp < 5°C. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £10.74
- Per week
- £75.20
- Per month
- £326.75
- Per year
- £3920.98
System specification
- Heat output
- 12 kW
- Type
- Ground-source (GSHP)
- Seasonal COP
- 3.5
- Electricity draw
- 3.43 kW/h
- Daily kWh
- 41.1 kWh
- Scenario
- 12 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 × 12 h = 41.1 kWh.
- Daily cost: 41.1 kWh × 26.11p/kWh = £10.74.
- Weekly: £10.74 × 7 = £75.20.
- Annual: £10.74 × 365 = £3920.98.
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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).