12 kW Air Source Heat Pump running cost — Always-on low-modulating (6 h equivalent)
A 12 kW Air Source Heat Pump (COP 2.5, BEIS data) draws 4.80 kW of electricity per hour. Running 6 hours/day uses 28.8 kWh and costs £7.52/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Air Source Heat Pump — Always-on low-modulating (6 h equivalent): 12 kW ÷ COP 2.5 = 4.80 kW electricity draw × 6 h = 28.8 kWh/day = £7.52/day. Weekly: £52.64. Annual: £2744.68. Context: Inverter heat pump in modulating mode, UK average. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £7.52
- Per week
- £52.64
- Per month
- £228.72
- Per year
- £2744.68
System specification
- Heat output
- 12 kW
- Type
- Air-source (ASHP)
- Seasonal COP
- 2.5
- Electricity draw
- 4.80 kW/h
- Daily kWh
- 28.8 kWh
- Scenario
- 6 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 × 6 h = 28.8 kWh.
- Daily cost: 28.8 kWh × 26.11p/kWh = £7.52.
- Weekly: £7.52 × 7 = £52.64.
- Annual: £7.52 × 365 = £2744.68.
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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).