Smarter Heating & Hot Water

COP Breakeven Calculator

Boiler vs heat-pump running cost: the COP a heat pump needs to match a gas boiler, then the saving (or extra cost) at a chosen COP.

Electricity Price £/kWh 0.27
Gas Price £/kWh 0.0678
Boiler Efficiency 0.90
Heat Pump COP 2.8
Electric / Gas Ratio
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Breakeven COP
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Heat pump vs boiler
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Positive = cheaper; negative = more costly

Formula

Ratio = Electricity ÷ Gas
Breakeven COP = Ratio × Boiler efficiency
Saving % = ((Heat-pump COP − Breakeven COP) ÷ Breakeven COP) × 100

Unit rates must be the same basis (usually £/kWh). Boiler efficiency is a fraction (0.9 = 90%). A heat pump cheaper than gas needs a seasonal COP above the breakeven figure.

Important: This is a unit-rate comparison only. It does not include standing charges, heat-loss, emitter temperature, or installation cost. Information is guidance; gas work needs a Gas Safe engineer.