12 kW Ground Source Heat Pump running cost — Always-on low-modulating (6 h equivalent)
A 12 kW Ground Source Heat Pump (COP 3.5, BEIS data) draws 3.43 kW of electricity per hour. Running 6 hours/day uses 20.6 kWh and costs £5.37/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Ground Source Heat Pump — Always-on low-modulating (6 h equivalent): 12 kW ÷ COP 3.5 = 3.43 kW electricity draw × 6 h = 20.6 kWh/day = £5.37/day. Weekly: £37.60. Annual: £1960.49. Context: Inverter heat pump in modulating mode, UK average. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £5.37
- Per week
- £37.60
- Per month
- £163.37
- Per year
- £1960.49
System specification
- Heat output
- 12 kW
- Type
- Ground-source (GSHP)
- Seasonal COP
- 3.5
- Electricity draw
- 3.43 kW/h
- Daily kWh
- 20.6 kWh
- Scenario
- 6 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 × 6 h = 20.6 kWh.
- Daily cost: 20.6 kWh × 26.11p/kWh = £5.37.
- Weekly: £5.37 × 7 = £37.60.
- Annual: £5.37 × 365 = £1960.49.
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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).