12 kW Ground Source Heat Pump running cost — Mild winter day (8 h)
A 12 kW Ground Source Heat Pump (COP 3.5, BEIS data) draws 3.43 kW of electricity per hour. Running 8 hours/day uses 27.4 kWh and costs £7.16/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Ground Source Heat Pump — Mild winter day (8 h): 12 kW ÷ COP 3.5 = 3.43 kW electricity draw × 8 h = 27.4 kWh/day = £7.16/day. Weekly: £50.13. Annual: £2613.98. Context: UK winter (Nov–Mar), outdoor temp 5–10°C. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £7.16
- Per week
- £50.13
- Per month
- £217.83
- Per year
- £2613.98
System specification
- Heat output
- 12 kW
- Type
- Ground-source (GSHP)
- Seasonal COP
- 3.5
- Electricity draw
- 3.43 kW/h
- Daily kWh
- 27.4 kWh
- Scenario
- 8 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 × 8 h = 27.4 kWh.
- Daily cost: 27.4 kWh × 26.11p/kWh = £7.16.
- Weekly: £7.16 × 7 = £50.13.
- Annual: £7.16 × 365 = £2613.98.
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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).