Heat pump running costs depend on efficiency (COP) and electricity rates. We explain the maths and provide real-world UK examples.
COP Explained Simply
Coefficient of Performance (COP) measures heat pump efficiency. A COP of 3 means 1 kWh electricity produces 3 kWh heat.
| COP | Heat Output | Effective Cost (£0.245/kWh) |
|---|---|---|
| 2.5 | 2.5 kWh | 9.8p per kWh heat |
| 3.0 | 3.0 kWh | 8.2p per kWh heat |
| 3.5 | 3.5 kWh | 7.0p per kWh heat |
| 4.0 | 4.0 kWh | 6.1p per kWh heat |
| 4.5 | 4.5 kWh | 5.4p per kWh heat |
Heat Pump vs Gas Boiler Running Costs
Gas Boiler: 90% efficient. Gas costs 7p/kWh. Real cost: 7.8p per kWh heat
Heat Pump (COP 3): Electricity 24.5p/kWh. Effective cost: 8.2p per kWh heat
Heat Pump (COP 4): Effective cost: 6.1p per kWh heat
A COP 4 heat pump is 20-30% cheaper to run than gas. COP 3 systems cost similar to gas but depend on electricity rates.
Real UK Household Examples
London Terrace, COP 3 Air Source: 15,000 kWh heating demand. Cost: £1,238 annually. Saves £0 vs gas (similar).
Manchester Detached, COP 3.5 Air Source: 20,000 kWh demand. Cost: £1,400 annually. Saves £240 vs gas boiler.
Scotland Ground Source, COP 4: 18,000 kWh demand. Cost: £1,101 annually. Saves £640 vs gas.
Seasonal Variations
Heat pumps are less efficient in winter (lower outdoor temperature). COP drops 0.5-1.0 points in January-February. Running costs increase 15-20% in winter months.
Calculate Your Costs
Get quotes from MCS installers to see your specific running cost projections.