A heat pump runs on electricity, the dearest fuel on the bill, yet a well-designed one heats a typical home for roughly what a gas boiler costs, and sometimes less. That apparent contradiction is the whole story of heat pump running costs, and it comes down to a single number, the SCOP, which measures how many units of heat the pump squeezes out of each unit of electricity. Get that number right and the pump is cheap to run; get it wrong, with a badly set-up system, and the expensive fuel bites. This guide works out what a heat pump costs a year, what decides the figure, and how to keep it down.
The short answer. A well-run air source heat pump heating a typical UK home uses roughly 3,500 to 4,500 kWh of electricity a year, costing around £850 to £1,100 at the standard rate of about 26p a unit. That is close to a gas boiler's yearly cost, and a heat-pump tariff or a well-designed low-temperature system can push it lower. A poorly set-up pump running at a high flow temperature can cost noticeably more, which is why the install matters as much as the kit.
The one number that decides the cost: SCOP
A heat pump does not turn electricity into heat the way a heater does. It uses electricity to move heat in from the outside air or the ground, so it delivers more heat energy than the electrical energy it consumes. The measure of this is the SCOP, the seasonal coefficient of performance, which averages the pump's efficiency across a whole heating season. A SCOP of 3.5 means that for every unit of electricity drawn, the pump delivers 3.5 units of heat into the home. A gas boiler, by contrast, delivers under one unit of heat per unit of gas, since some goes up the flue.
That multiplier is what lets an appliance running on 26p electricity compete with one running on 7p gas. At a SCOP of 3.5, each unit of heat costs the electricity price divided by 3.5, which is roughly 26p divided by 3.5, or about 7.5p per unit of heat, right alongside gas. Push the SCOP up to 4 and the heat costs about 6.5p a unit, cheaper than gas. Let it drop to 2.5, which happens with a poorly designed system or very cold weather, and each unit of heat climbs to around 10p, dearer than gas. The SCOP is everything, and the heat pumps explained guide covers how it is set.
A worked yearly cost
The sum is the same one used for any appliance: the heat the home needs, divided by the SCOP to find the electricity used, multiplied by the unit rate. Take a typical home needing around 12,000 kWh of heat across a year. At a SCOP of 3.5 that is 12,000 divided by 3.5, or about 3,430 kWh of electricity. At 26p a unit that comes to roughly £890 a year. The table shows how the figure shifts with the SCOP and the tariff.
| System and tariff | SCOP | Electricity used | Yearly running cost |
|---|---|---|---|
| Standard rate, average install | 3.0 | ~4,000 kWh | ~£1,045 |
| Standard rate, well-designed | 3.5 | ~3,430 kWh | ~£895 |
| Standard rate, excellent install | 4.0 | ~3,000 kWh | ~£785 |
| Heat-pump tariff (~15p), SCOP 3.5 | 3.5 | ~3,430 kWh | ~£515 |
Worked examples for a home needing about 12,000 kWh of heat a year, at a 26p standard rate and an illustrative 15p heat-pump tariff. Your figure depends on the home's heat demand, the SCOP achieved and your tariff.
Two things stand out. A standard-rate heat pump lands close to a typical gas heating bill, which is why it is fair to call it cost-neutral to run for most homes rather than a clear win or loss. And a dedicated heat-pump electricity tariff, which charges a low rate for the hours the pump runs hardest, can cut the bill by a third or more, which is often what tips a heat pump ahead of gas on cost.
Why the flow temperature matters so much
The single biggest thing you control, once the pump is installed, is the flow temperature, the temperature of the water it sends to the radiators or underfloor loops. A heat pump is far more efficient when it heats water gently, to 35 or 40 degrees, than when it is pushed to 55 or 60 to mimic a boiler. Every degree lower lifts the SCOP and lowers the bill. This is why heat pumps pair so well with underfloor heating and larger radiators, which give off enough warmth at a low water temperature, and why a system sized and set up to run cool costs much less than one straining to run hot. The same principle scaled down applies to a gas boiler's flow temperature, but for a heat pump it is the difference between cheap and expensive heat.
The house matters more than the pump
A heat pump's running cost is decided as much by the building as by the appliance. A well-insulated, draught-sealed home needs less heat in the first place, so the pump runs less and at a gentler output, keeping the SCOP high. A leaky, poorly insulated home needs more heat and often demands a higher flow temperature to keep up, which drags the efficiency down and the bill up. This is why the advice for anyone considering a heat pump is to sort the fabric first: top up the loft insulation, seal the draughts, and the pump you then fit will be smaller, cheaper to run and more comfortable. Spending on insulation before the pump is almost always money better spent than a bigger pump into a cold house.
Keeping the running cost down
Several levers bring a heat pump's bill down, and most cost nothing. Run it at the lowest flow temperature that keeps the house comfortable, and resist the urge to turn it up in mild weather. Let it run steadily rather than blasting on and off, since heat pumps are most efficient ticking over gently for long stretches. Move to a dedicated heat-pump tariff if your supplier offers one, as the cheaper units make a real difference. Keep the outdoor unit clear of leaves and snow so it can breathe. And improve the home's insulation over time, because every improvement lets the pump work less hard. Done together these can move a system from the top of the cost table toward the bottom.
The bottom line
A heat pump costs roughly £850 to £1,100 a year to heat a typical home at the standard electricity rate, close to a gas boiler, and a heat-pump tariff or an efficient low-temperature install can bring it well below that. The figure is driven by the SCOP, and the SCOP is driven by how the system is set up and how well the house holds heat, far more than by the badge on the unit. For the head-to-head against gas see heat pump running cost vs a gas boiler, and to put your own numbers in, the heat pump running cost calculator does the sum for you.
Common questions
How much does a heat pump cost to run per year?
Around £850 to £1,100 a year to heat a typical UK home at the standard electricity rate of about 26p a unit, using roughly 3,500 to 4,500 kWh of electricity. A dedicated heat-pump tariff can cut that by a third or more.
Is a heat pump expensive to run?
Not if it is set up well. Because it delivers three to four units of heat per unit of electricity, its running cost lands close to a gas boiler despite electricity being the dearer fuel. A poorly designed system running at a high flow temperature costs more.
What is SCOP and why does it matter?
SCOP is the seasonal coefficient of performance, the average number of units of heat a pump delivers per unit of electricity across a heating season. A SCOP of 3.5 means each unit of heat costs about 7.5p at a 26p electricity rate, right alongside gas. A higher SCOP means a lower bill.
How can I reduce my heat pump running costs?
Run it at the lowest flow temperature that keeps you comfortable, let it run steadily rather than cycling on and off, move to a heat-pump electricity tariff if available, keep the outdoor unit clear, and improve the home's insulation so the pump works less hard.