A heat pump typically costs somewhere between £700 and £2,500 a year to run in a UK home, depending on property size, insulation standard, and how the system is set up and used, with a well-insulated 3-bed semi on a decently performing system usually landing in the £900-£1,300 region. That’s a wide range on purpose: running costs are driven far more by your specific property and system setup than by the fact that it’s a heat pump rather than a boiler, and anyone quoting you a single national average figure is skipping the part that actually matters.
I’ll walk through how these figures are actually worked out, what makes the biggest difference to your bill, and how to get a number that reflects your own home rather than a national average.
How is a heat pump’s running cost actually calculated?
A heat pump’s running cost is worked out from three numbers: your annual heat demand, your system’s SCOP, and your electricity unit rate. Divide heat demand by SCOP to get electricity consumed, then multiply by the unit rate. The maths is simpler than most people expect, and understanding it explains almost everything else in this article. There are three numbers involved:
- Annual heat demand: the total heat energy (in kWh) your home needs over a year to stay warm and provide hot water. This comes from a heat loss calculation and depends on floor area, insulation, wall/roof/floor construction, window performance, and ventilation.
- SCOP (Seasonal Coefficient of Performance): the average ratio of heat output to electricity input across a full year. A SCOP of 3.5 means the heat pump delivers 3.5 kWh of heat for every 1 kWh of electricity it consumes.
- Electricity unit rate: what you pay per kWh, in pence.
The formula is:
Annual heat demand (kWh) ÷ SCOP = electricity consumed (kWh), then electricity consumed × unit rate = annual running cost.
So a home with a 12,000 kWh annual heat demand and a heat pump running at a SCOP of 3.4 would consume roughly 3,530 kWh of electricity a year. At an illustrative rate of around 27p/kWh, that comes to roughly £950 a year. Change any one of those three inputs and the answer moves significantly, which is exactly why running cost estimates need to be specific to your home rather than generic.
A quick note on unit rates before we go further: electricity and gas prices in the UK move with the Ofgem price cap, which is reviewed quarterly, plus whatever tariff you’re actually on. Every cost figure in this article uses round, illustrative unit rates, roughly 25-30p/kWh for electricity and roughly 6-7p/kWh for gas, purely to demonstrate the calculation method. For a precise, current figure, check the unit rates on your actual tariff, since real prices will differ from these illustrative ones.
Why does SCOP matter so much to my heat pump bill?
SCOP matters enormously because it sits on the bottom of the division sum that determines electricity consumption, so a poorly performing system doesn’t cost a bit more to run. It can cost dramatically more, even with identical heat demand and identical electricity prices. Of the three variables above, SCOP is the one installers and homeowners argue about most, and for good reason.
Here’s the same 12,000 kWh annual heat demand run through two different performance levels, using an illustrative electricity rate of 27p/kWh:
| Scenario | Annual heat demand | COP/SCOP | Electricity consumed | Illustrative annual cost |
|---|---|---|---|---|
| Poorly set up system | 12,000 kWh | 2.5 | 4,800 kWh | £1,296 |
| Well set up system | 12,000 kWh | 4.0 | 3,000 kWh | £810 |
That’s an illustrative saving of nearly £500 a year, roughly 37% lower, on the exact same house with the exact same heating requirement. The only thing that changed is how efficiently the heat pump is running. This is why a badly commissioned installation (oversized radiators skipped, flow temperature left too high, controls left on factory defaults) can leave a homeowner paying well over the odds indefinitely, while a properly designed and commissioned system delivers the efficiency the technology is actually capable of. It’s also why we spend time at the design and commissioning stage getting flow temperatures and radiator sizing right, rather than just fitting a unit and leaving.
How much does a heat pump cost to run by property type?
Illustrative annual running costs range from around £475 for a well-insulated 1-2 bed flat up to around £2,505 for a poorly insulated older property, with a typical 3-bed semi landing around £950. The table below gives ballpark figures by property type, based on typical UK heat demand, typical SCOP performance for a reasonably well-designed system, and an illustrative electricity rate of around 27p/kWh. These are estimates to give you a sense of scale, not a quote, and not a substitute for a proper heat loss calculation on your own home.
| Property type | Typical annual heat demand | Typical SCOP | Electricity consumed | Illustrative annual running cost |
|---|---|---|---|---|
| 1-2 bed flat (well insulated) | ~6,000 kWh | 3.4 | ~1,765 kWh | ~£475 |
| 3-bed semi (average insulation) | ~12,000 kWh | 3.4 | ~3,530 kWh | ~£950 |
| 4-bed detached (average insulation) | ~18,000 kWh | 3.3 | ~5,455 kWh | ~£1,475 |
| Poorly insulated older property (solid wall, limited loft insulation) | ~26,000 kWh | 2.8 | ~9,285 kWh | ~£2,505 |
Notice the poorly insulated property doesn’t just have a higher heat demand. It also has a lower achievable SCOP, because higher flow temperatures are typically needed to heat the same rooms adequately when the fabric is leaking heat faster than it should. That combination is why draughty, under-insulated homes see the biggest bills, and often the biggest improvement potential once insulation and radiator sizing are addressed alongside the heat pump itself.
How does a heat pump compare to a gas boiler and electric heating on running cost?
A well-run heat pump comes out roughly comparable to a modern gas boiler on running cost and dramatically cheaper than direct electric resistance heating. Using the 3-bed semi example above (12,000 kWh annual heat demand) and illustrative unit rates of 27p/kWh for electricity and 6.5p/kWh for gas:
| Heating system | Typical efficiency | Energy consumed | Illustrative annual running cost |
|---|---|---|---|
| Air source heat pump (SCOP 3.4) | 340% | ~3,530 kWh electricity | ~£950 |
| Modern gas boiler | ~85% | ~14,120 kWh gas | ~£920 |
| Electric resistance heating (panel heaters, storage heaters) | ~100% | ~12,000 kWh electricity | ~£3,240 |
The headline takeaway: because electricity typically costs several times more per kWh than gas, a heat pump needs a decent SCOP just to match a modern gas boiler on running cost. At these illustrative rates the two come out broadly comparable, with the heat pump often edging ahead once it’s well designed and on a favourable tariff. What a heat pump comprehensively beats, every time, is direct electric heating, because it’s moving heat from outside air rather than generating it from scratch. As the electricity-to-gas price ratio shifts over time (and it does move with the market), the gap between heat pump and gas running costs shifts too, which is another reason to check current rates rather than rely on a fixed comparison.
What factors actually swing your real-world heat pump bill?
Insulation quality, flow temperature, thermostat habits, hot water usage, your electricity tariff, and house size and occupancy patterns are what push individual bills up or down considerably. The numbers above assume a “typical” well-run system, but in practice:
- Insulation quality. Every degree of heat lost through walls, roof, floor, and draughts has to be replaced by the heat pump. Insulation improvements reduce heat demand directly, which reduces electricity consumption regardless of SCOP.
- Flow temperature setting. This is the single biggest lever on efficiency. A heat pump running at 35-40°C flow temperature will achieve a noticeably better COP than the same unit pushed to 55-60°C, because the compressor has to work harder to lift the temperature further.
- Thermostat habits. Heat pumps are most efficient running gently and steadily rather than being switched off and blasted back up. Large temperature swings force higher flow temperatures and short, inefficient bursts of high output.
- Hot water usage. Heating water to 50-55°C for a cylinder is inherently less efficient than space heating at lower flow temperatures, so households with high hot water demand (large families, frequent baths) will see a bigger contribution from hot water to their total bill.
- Your electricity tariff. Standard variable tariffs aren’t the only option. A number of UK suppliers now offer tariffs specifically aimed at heat pump owners, or cheaper off-peak rates that reward running the system (or pre-heating hot water) outside peak hours. These products and their pricing change fairly often, so it’s worth checking what’s currently available from suppliers in your area rather than assuming your existing tariff is the cheapest fit.
- House size and occupancy patterns. A home that’s occupied and heated all day has different demand patterns to one heated mainly mornings and evenings.
How can I reduce my heat pump running costs?
You reduce heat pump running costs mainly by changing how the system is configured and used, not by buying a bigger or more expensive unit. Most of the effective levers are:
- Run the lowest flow temperature that still keeps rooms comfortable. This usually means correctly sized radiators (or underfloor heating) able to deliver enough heat output at a lower water temperature. Get this right at installation and it pays back every single day the system runs.
- Use weather compensation controls. A weather-compensated system automatically adjusts flow temperature based on outdoor conditions, so it isn’t running hotter than necessary on a mild day.
- Avoid unnecessary overnight setback. Unlike a gas boiler, a heat pump generally performs better running steadily at a lower, consistent temperature than being switched off overnight and having to recover the heat loss in the morning with a burst of high-flow-temperature output. A modest, consistent setpoint is usually cheaper than an aggressive on/off schedule.
- Get radiators sized correctly for lower flow temperatures. Undersized radiators are one of the most common reasons a heat pump ends up running at a higher, less efficient flow temperature than it should.
- Address insulation gaps. Loft top-ups, draught-proofing, and cavity or underfloor insulation reduce heat demand directly and are often the most cost-effective improvement available before or alongside a heat pump installation.
- Use smart heating schedules sensibly. Smart controls that anticipate warm-up time and maintain steady temperatures generally outperform manual on/off toggling.
- Consider a heat-pump-friendly tariff. If one is available and suits your usage pattern, shifting some hot water heating or pre-heating to cheaper off-peak hours can meaningfully reduce cost.
Why does my heat pump bill vary so much between seasons?
Your bill varies by season because an annual running cost figure is an average across a full year, and that average hides substantial seasonal swings. A heat pump working to maintain a warm home when it’s 2°C outside is doing considerably more work, and consuming more electricity per hour, than the same system on a mild October evening. It’s entirely normal to see winter months (December to February) account for a disproportionate share of the annual bill, sometimes 40-50% of total yearly running cost concentrated into the coldest quarter, while spring and autumn running costs are comparatively modest and summer costs are largely just hot water.
If your January bill looks alarming compared with your April bill, that’s expected behaviour, not necessarily a sign something’s wrong. What’s worth checking is how that winter cost compares with a cold spell in previous years, or with the running cost estimate given at installation for a similarly cold period. That’s a more useful comparison than month-to-month swings within the same winter.
How do I estimate my own heat pump running cost?
You estimate your own running cost by getting a proper heat loss calculation done, asking your installer for a property-specific projection, and checking your actual SCOP after the first year of use. Every figure in this article is illustrative, based on typical UK houses and typical unit rates. Your actual number depends on your specific property, so here’s how to get a figure that means something for your home:
- Get a proper heat loss calculation done. This is a room-by-room assessment of how much heat your home loses, based on its actual construction, insulation, glazing, and floor area, not a rule-of-thumb estimate. It’s the foundation for both correct system sizing and an accurate running cost projection.
- Ask your installer for a running cost estimate specific to your property. A competent installer should be able to combine your heat loss figure with the expected SCOP of the proposed system and current unit rates to give you a realistic annual estimate, not a generic national average.
- Check your actual SCOP after the first year via smart monitoring. Most modern heat pump systems can be fitted with monitoring that tracks electricity input and heat output, letting you see your real achieved SCOP rather than the design-stage estimate. This is useful. It tells you whether the system is performing as intended and flags whether flow temperatures or controls need adjusting.
- Compare like with like when reviewing your bill. Look at cost per kWh of heat delivered, or compare against a similarly cold period in a previous year, rather than comparing a winter month against a summer one.
Running cost is ultimately a function of your specific building, your specific system design, and how it’s used day to day, which is exactly why we work out a heat loss calculation and a tailored running cost estimate for every property before recommending a system, rather than quoting a one-size-fits-all number.
