12 kW Ground Source Heat Pump running cost — Domestic hot water only (2 h)
A 12 kW Ground Source Heat Pump (COP 3.5, BEIS data) draws 3.43 kW of electricity per hour. Running 2 hours/day uses 6.9 kWh and costs £1.79/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Ground Source Heat Pump — Domestic hot water only (2 h): 12 kW ÷ COP 3.5 = 3.43 kW electricity draw × 2 h = 6.9 kWh/day = £1.79/day. Weekly: £12.53. Annual: £653.50. Context: Summer use, hot water production only. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £1.79
- Per week
- £12.53
- Per month
- £54.46
- Per year
- £653.50
System specification
- Heat output
- 12 kW
- Type
- Ground-source (GSHP)
- Seasonal COP
- 3.5
- Electricity draw
- 3.43 kW/h
- Daily kWh
- 6.9 kWh
- Scenario
- 2 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 × 2 h = 6.9 kWh.
- Daily cost: 6.9 kWh × 26.11p/kWh = £1.79.
- Weekly: £1.79 × 7 = £12.53.
- Annual: £1.79 × 365 = £653.50.
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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).