Heat pump vs electric heaters: how much could you save?
Compare the yearly running cost of electric heaters and a heat pump from your actual heating use. With a measured seasonal efficiency of 3.4, the heating bill falls by more than two thirds.
- Heat pump electricity use
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- Current cost (heaters)
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- Cost with a heat pump
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- Simple payback
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Assumption: a resistive heater turns about 1 kWh of electricity into 1 kWh of heat, so its annual use ≈ your heat demand. Measured efficiencies: Fraunhofer ISE “WP-QS im Bestand” field study (77 heat pumps monitored in real homes). Standing charges, maintenance and any cooling use are not included. Results are indicative estimates based on the values you enter. Always check your appliance labels, your tariff and the manufacturer’s data.
- A resistive electric heater delivers about 1 kWh of heat per kWh used; air-to-water heat pumps averaged 3.4 in real homes (Fraunhofer ISE field study, 61 systems).
- UK example: 6,000 kWh a year of electric heating at the price cap (26.32p/kWh) costs about £1,579; the same heat from a heat pump at 3.4 costs about £464, saving about £1,115 a year.
- US example at the 18.31¢ average: about $1,099 down to $323, a saving of about $776.
- Results vary widely between installations (2.6 to 4.9 measured for air source): design and installation quality matter as much as the unit.
The calculator starts from how much electricity your heaters use today. Because a resistive heater turns practically all of its electricity into heat, that figure is a good estimate of your home’s heat demand. A heat pump delivers the same heat with less electricity, divided by its seasonal efficiency.
How to find your heating consumption
- All-electric home: compare winter bills with months when the heating is off. The extra consumption over the season is a good approximation.
- Smart meter: your supplier’s app or online account shows monthly use, which makes the winter increase easy to spot.
- Otherwise: your home’s energy performance certificate (EPC) or an energy audit gives an estimate of space heating demand.
Leave out hot water unless the heat pump will provide it too.
Seasonal efficiency is the key number
The seasonal coefficient of performance (SCOP), also called seasonal performance factor, tells you how many kWh of heat the heat pump delivers on average for each kWh of electricity over a full heating season.
Label figures come from lab tests. In real homes, Fraunhofer ISE monitored 77 heat pumps in existing houses in Germany for four years, most of them built before 1995:
| Type | Measured average | Range |
|---|---|---|
| Air-to-water (61 systems) | 3.4 | 2.6 to 4.9 |
| Ground source (16 systems) | 4.3 | 3.6 to 5.4 |
German winters are broadly similar to or colder than most of the UK, so 3.4 is a reasonable starting point for British homes. Very cold US climates may see lower figures unless the unit is designed for low temperatures.
Worked example
For a home using 6,000 kWh a year of electric heating:
| Option | Electricity used | UK cost (26.32p) | US cost (18.31¢) |
|---|---|---|---|
| Electric heaters | 6,000 kWh | £1,579 | $1,099 |
| Heat pump, 2.6 | 2,308 kWh | £607 | $423 |
| Heat pump, 3.4 | 1,765 kWh | £464 | $323 |
| Heat pump, 4.9 | 1,224 kWh | £322 | $224 |
UK: storage heaters change the maths
Many electrically heated British homes use night storage heaters on an Economy 7 or similar tariff, charging at a cheaper overnight rate. In that case the comparison is not with the price cap’s single rate: enter your actual average price for heating electricity in the calculator, and compare it with the rate the heat pump would pay (heat pumps run mostly during the day unless you have a suitable time-of-use tariff).
Air-to-air or air-to-water?
- Air-to-water heats water for radiators or underfloor heating. In a home with no wet heating system, the pipework and radiators add a lot to the cost.
- Air-to-air (a “ductless mini-split” in the US, sometimes called a reversible air conditioner in Europe) blows warm air into rooms and can directly replace electric heaters. Use the SCOP or HSPF on its label, with some margin since real-world results are usually lower.
Simple payback
If you enter the installed cost (after any grant or rebate you are entitled to), the calculator estimates a simple payback: cost ÷ annual saving. Treat it as an order of magnitude: it ignores maintenance, future price changes and equipment life. Get several quotes and ask how the system was sized; the Fraunhofer study found many units oversized relative to actual demand, which hurts efficiency.
What the calculation leaves out
- Efficiency drops in very cold weather, and some systems use a backup resistive element.
- Summer cooling with a reversible unit adds consumption not counted here.
- Standing charges are ignored because they usually do not change.