12 kW Air Source Heat Pump running cost — Domestic hot water only (2 h)
A 12 kW Air Source Heat Pump (COP 2.5, BEIS data) draws 4.80 kW of electricity per hour. Running 2 hours/day uses 9.6 kWh and costs £2.51/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
12 kW Air Source Heat Pump — Domestic hot water only (2 h): 12 kW ÷ COP 2.5 = 4.80 kW electricity draw × 2 h = 9.6 kWh/day = £2.51/day. Weekly: £17.55. Annual: £914.89. Context: Summer use, hot water production only. Source: DESNZ/BEIS (OGL v3.0) + Ofgem.
- Per day
- £2.51
- Per week
- £17.55
- Per month
- £76.24
- Per year
- £914.89
System specification
- Heat output
- 12 kW
- Type
- Air-source (ASHP)
- Seasonal COP
- 2.5
- Electricity draw
- 4.80 kW/h
- Daily kWh
- 9.6 kWh
- Scenario
- 2 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 × 2 h = 9.6 kWh.
- Daily cost: 9.6 kWh × 26.11p/kWh = £2.51.
- Weekly: £2.51 × 7 = £17.55.
- Annual: £2.51 × 365 = £914.89.
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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).