12 kW Air Source Heat Pump running cost — All-day heating (18 h)
A 12 kW Air Source Heat Pump (COP 2.5, BEIS data) draws 4.80 kW of electricity per hour. Running 18 hours/day uses 86.4 kWh and costs £22.56/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Air Source Heat Pump — All-day heating (18 h): 12 kW ÷ COP 2.5 = 4.80 kW electricity draw × 18 h = 86.4 kWh/day = £22.56/day. Weekly: £157.91. Annual: £8234.05. Context: UK winter, poor insulation or large detached home. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £22.56
- Per week
- £157.91
- Per month
- £686.17
- Per year
- £8234.05
System specification
- Heat output
- 12 kW
- Type
- Air-source (ASHP)
- Seasonal COP
- 2.5
- Electricity draw
- 4.80 kW/h
- Daily kWh
- 86.4 kWh
- Scenario
- 18 h/day
BEIS Heat Pump Information Note 2024 — 12 kW ASHP, conservative SCOP 2.5 for larger homes
How the cost is worked out
- Electricity draw per hour: 12 kW ÷ COP 2.5 = 4.80 kW.
- Daily kWh: 4.80 kW × 18 h = 86.4 kWh.
- Daily cost: 86.4 kWh × 26.11p/kWh = £22.56.
- Weekly: £22.56 × 7 = £157.91.
- Annual: £22.56 × 365 = £8234.05.
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COP 2.5 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).