Running costs
The cost of running a heat pump depends on its efficiency and the price you pay for electricity. While electricity is currently more expensive per unit than gas, the high efficiency of a heat pump often makes the total running costs comparable to or lower than a gas boiler.
Running Cost Estimator
Use this tool to compare the estimated annual running costs of a heat pump against your current heating system.
Heat Pump Settings
Efficiency: COP and SCOP
To understand running costs, you need to know two terms:
- COP (Coefficient of Performance): The efficiency at a specific moment. If a heat pump has a COP of 3.0, it is producing 3 units of heat for every 1 unit of electricity used.
- SCOP (Seasonal Coefficient of Performance): The average efficiency over an entire year, accounting for seasonal temperature changes. A typical SCOP for an air source heat pump is between 2.8 and 3.5.
Factors that affect your costs
1. Outside temperature
Heat pumps have to work harder to extract heat when it is very cold outside. This means their efficiency drops slightly in mid-winter.
2. Flow temperature
This is the temperature of the water sent to your radiators.
- Low flow (35-45°C): Highest efficiency. Requires larger radiators or underfloor heating.
- High flow (55-65°C): Lower efficiency. Often used in older homes with standard-sized radiators.
3. Your electricity tariff
Because heat pumps use significant electricity, choosing the right tariff is essential.
- Time-of-Use (TOU) tariffs: Tariffs like “Octopus Cosy” or “Agile” offer cheaper electricity during the night or specific “off-peak” windows, allowing you to heat your hot water tank or pre-heat the house for less.
4. Insulation
A poorly insulated home loses heat quickly, meaning the heat pump has to run more often. Insulation is the single best way to lower your running costs.
Typical cost comparison (Annual)
Based on a typical 3-bedroom semi-detached house using 12,000 kWh of heat per year.
| Heating System | Efficiency | Energy Needed | Est. Annual Cost |
|---|---|---|---|
| Old Gas Boiler | 70% | 17,142 kWh (Gas) | £1,200 |
| New Gas Boiler | 92% | 13,043 kWh (Gas) | £910 |
| Heat Pump | 300% (SCOP 3.0) | 4,000 kWh (Elec) | £960* |
*Assumes electricity at 24p/kWh. Costs can be significantly lower if using a smart tariff or solar panels.
Interactive Cost Estimator
Use this tool to compare your current heating costs with an air source heat pump.
Heat Pump Settings
Pro Tip: Combining a heat pump with solar panels and a battery can reduce your net running costs to near zero during the spring and autumn months.