What Heat Pumps Actually Achieve in Real British Homes
See measured heat-pump efficiency in British homes, including cold-weather performance, hot water, flow temperature and installation costs.
What the number means
Coefficient of performance (COP) is the heat delivered for each unit of electricity used. A COP of 4 means four kilowatt-hours of heat for one kilowatt-hour of electricity. Running cost also depends on energy prices and the heating demand of the home.
What these homes actually achieve
The main figures use comparable whole-system measurements and show the sample size beside each result.
Whole system metered
The fullest arrangement: what went in and what came out, both measured.
- Everything together
- 3.94middle half 3.55–4.27383 systems
- Heating the rooms
- 4.22middle half 3.84–4.61262 systems
- Heating the hot water
- 3.08middle half 2.64–3.44241 systems
The colder the water, the better it does
Medians for whole-system-metered installations, with the sample size shown for each group.
- Flow temperature 35 to 45°C
- 3.8051 systems
- Flow temperature Under 35°C
- 4.0396 systems
Based on 455 monitored systems from households that chose to publish their results. This is not a representative sample of all British heat pumps.
Performance in cold weather
A separate government-funded trial measured performance across the seasons. Its table shows that heat pumps continued to deliver heat in the coldest temperature band, although they used more electricity for each unit of heat than in milder weather.
Electrification of Heat Demonstration Project
2.74
units of heat for each unit of electricity, over a whole metered year, in the middle of 478 air source installations. The middle half fell between 2.46 and 3.03.
The ratio compares heat measured from the heat pump with whole-system electricity, including back-up and immersion heating. It is not a seasonal performance factor. Trial households volunteered, so this is not a market-wide average.
Performance by outside temperature
Daily results from 737homes, grouped by average outside temperature.
| Outside temperature | Heat per unit of electricity | Homes | Days |
|---|---|---|---|
| -5°C to -2.5°C | 2.24 | 503 | 2,069 |
| -2.5°C to 0°C | 2.35 | 658 | 6,433 |
| 0°C to 2.5°C | 2.56 | 732 | 25,618 |
| 2.5°C to 5°C | 2.74 | 733 | 49,904 |
| 5°C to 7.5°C | 2.94 | 733 | 68,825 |
| 7.5°C to 10°C | 3.04 | 733 | 74,648 |
| 10°C to 12.5°C | 2.95 | 734 | 76,597 |
| 12.5°C to 15°C | 2.55 | 730 | 83,006 |
| 15°C to 17.5°C | 2.23 | 730 | 61,486 |
| 17.5°C to 20°C | 1.95 | 720 | 22,674 |
| 20°C to 22.5°C | 1.75 | 677 | 3,882 |
| 22.5°C and above | 1.72 | 517 | 1,557 |
Hot water and flow temperature
In the comparable whole-system sample, room heating has a median COP of 4.22across 262 systems. Hot water has a median of 3.08 across 241 systems.
Hot water generally needs a higher temperature than room heating, which tends to reduce performance.
Flow temperature is the temperature of the water sent around the home. The Under 35°C group has a median COP of 4.03 across 96 systems, compared with 3.80 across 51 systems in the 35 to 45°C group.
The groups contain different homes, so this shows an association and does not predict the result of changing one system’s setting.
What the electricity itself costs is the other half of the sum, and examples of dedicated heat-pump tariffs include Cosy Octopus and EDF Heat Pump Tracker. If a grant is part of your arithmetic, see the current Boiler Upgrade Scheme terms.
What one costs to install
The final domestic Renewable Heat Incentive statistics include about 84,840 reported installation costs across heat pumps, biomass and solar thermal; 71,360 are air- or ground-source heat-pump applications. The final statistics cover Great Britain between April 2014 and March 2024.
These are self-reported historic prices, not current quotes, and they are not adjusted for inflation.
Domestic Renewable Heat Incentive
Non-Domestic and Domestic Renewable Heat Incentive (RHI) monthly deployment data. Department for Energy Security and Net Zero, from Ofgem data. Final edition, March 2024.
What 84,840 contributing applications reported as installation cost, in Great Britain, between April 2014 to March 2024. These are prices from across that whole decade, in the money of the year they were paid, and they have not been adjusted for inflation. Read them as a record of what people paid, not as a quote for today.
| Size band (kW) | Typical cost | Per kW installed | Installations |
|---|---|---|---|
| Air source heat pump | |||
| Less than 5 | £7,500middle half £5,500 to £8,590 | £1,500middle half £1,200 to £1,830 | 9,050 |
| 6 - 10 | £9,400middle half £7,320 to £12,240 | £1,190middle half £930 to £1,530 | 24,980 |
| 11 - 15 | £12,500middle half £10,000 to £15,000 | £1,000middle half £810 to £1,220 | 17,480 |
| 16 - 20 | £14,000middle half £11,000 to £16,740 | £860middle half £680 to £1,010 | 7,400 |
| 21 - 25 | £19,000middle half £15,730 to £24,390 | £820middle half £690 to £1,050 | 690 |
| 26 - 30 | £21,940middle half £18,000 to £27,440 | £800middle half £640 to £1,010 | 270 |
| 31 - 35 | £21,650middle half £17,000 to £27,000 | £670middle half £530 to £840 | 260 |
| 36 - 40 | £29,230middle half £20,000 to £33,910 | £800middle half £550 to £940 | 20 |
| 41 - 45 | £26,580middle half £19,910 to £32,600 | £600middle half £460 to £750 | 30 |
| Biomass | |||
| Less than 5 | Not published — typical cost, Biomass, Less than 5 kW. No installations in this band, so there is no cost to reportmiddle half not published — No installations in this band, so there is no cost to report | Not published — cost per kW, Biomass, Less than 5 kW. No installations in this band, so there is no cost to reportmiddle half not published — No installations in this band, so there is no cost to report | 0 |
| 6 - 10 | £13,000middle half £10,000 to £16,100 | £1,360middle half £1,000 to £1,700 | 120 |
| 11 - 15 | £12,000middle half £8,930 to £16,000 | £840middle half £630 to £1,110 | 1,250 |
| 16 - 20 | £12,790middle half £9,070 to £16,600 | £690middle half £500 to £880 | 1,350 |
| 21 - 25 | £14,260middle half £10,000 to £18,000 | £600middle half £430 to £720 | 2,250 |
| 26 - 30 | £16,440middle half £13,000 to £20,000 | £600middle half £470 to £730 | 1,520 |
| 31 - 35 | £18,000middle half £17,340 to £23,310 | £510middle half £510 to £690 | 1,300 |
| 36 - 40 | £19,250middle half £15,000 to £25,000 | £500middle half £390 to £660 | 820 |
| 41 - 45 | £25,780middle half £18,490 to £34,000 | £580middle half £420 to £760 | 620 |
| Ground source heat pump | |||
| Less than 5 | £8,590middle half £7,210 to £13,490 | £1,800middle half not published — The publisher printed zero here, which is an absent figure rather than a price of nothing | 350 |
| 6 - 10 | £15,000middle half £10,900 to £20,000 | £1,890middle half £1,000 to £2,500 | 3,090 |
| 11 - 15 | £20,000middle half £15,000 to £27,660 | £1,660middle half £630 to £2,230 | 4,550 |
| 16 - 20 | £26,860middle half £20,000 to £35,000 | £1,520middle half £500 to £1,960 | 1,000 |
| 21 - 25 | £30,870middle half £24,920 to £40,290 | £1,360middle half £430 to £1,820 | 1,300 |
| 26 - 30 | £40,060middle half £30,000 to £55,510 | £1,430middle half £470 to £1,970 | 450 |
| 31 - 35 | £49,880middle half £35,040 to £71,070 | £1,460middle half £510 to £2,140 | 170 |
| 36 - 40 | £45,490middle half £32,670 to £67,370 | £1,180middle half £390 to £1,730 | 120 |
| 41 - 45 | £50,000middle half £38,750 to £75,000 | £1,140middle half £420 to £1,720 | 150 |
| Solar thermal | |||
| Less than 5 | £4,500middle half £3,450 to £5,990 | £1,780middle half not published — The publisher printed zero here, which is an absent figure rather than a price of nothing | 4,080 |
| 6 - 10 | £6,000middle half £4,500 to £8,430 | £920middle half £1,000 to £1,240 | 150 |
| 11 - 15 | £4,990middle half £4,130 to £7,530 | £380middle half £630 to £640 | 20 |
| 16 - 20 | Not published — typical cost, Solar thermal, 16 - 20 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Not published — cost per kW, Solar thermal, 16 - 20 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Withheld |
| 26 - 30 | Not published — typical cost, Solar thermal, 26 - 30 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Not published — cost per kW, Solar thermal, 26 - 30 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Withheld |
| 31 - 35 | Not published — typical cost, Solar thermal, 31 - 35 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Not published — cost per kW, Solar thermal, 31 - 35 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Withheld |
| 36 - 40 | Not published — typical cost, Solar thermal, 36 - 40 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Not published — cost per kW, Solar thermal, 36 - 40 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Withheld |
| 41 - 45 | Not published — typical cost, Solar thermal, 41 - 45 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Not published — cost per kW, Solar thermal, 41 - 45 kW. Withheld: fewer than 20 installations in this bandmiddle half not published — Withheld: fewer than 20 installations in this band | Withheld |
There is no total row, because the size bands do not join up: Less than 5 is followed by 6 - 10, so a 5.5 kW installation is in neither and the bands cannot be added. Bands with fewer than 20 installations are withheld by the publisher. Where the publisher printed a zero we show what it means rather than the number, because a zero here is an absent figure and never a price.
Before you use any of these figures
- The prices are self-reported and were never audited
- Self-reported by applicants on the RHI application form and not validated by Ofgem. DESNZ removed installations with a zero capacity or cost and any above 45 kW, but did not audit prices.
- Nominal money across a decade, not today’s prices
- Nominal pounds spanning April 2014 to March 2024, undeflated. There is no deflator in the release, and these figures must not be rebased into today’s money.
- A published zero is a missing figure, never a price of nothing
- A published zero is an absent figure, never a price. Where a technology and capacity band has no installations the workbook writes 0 rather than a suppression marker.
- The size bands do not join up and cannot be added together
- The capacity bands are the publisher’s and do not tile: “Less than 5” is followed by “6 - 10”, so nothing between 5 and 6 kW appears in either, and the bands are not a partition that can be totalled.
- Great Britain, and a scheme that has closed
- Great Britain only, and a closed scheme: the domestic RHI stopped taking applications on 31 March 2022 and was replaced by the Boiler Upgrade Scheme.
- This edition replaces its predecessor rather than extending it
- The register revises downward, so this edition supersedes rather than extends its predecessor. Earlier editions disagree with it and must not be spliced onto it.
- The scheme’s efficiency figures are design values and are not shown here
- Seasonal performance factors here are design values from the MCS certificate, truncated at the scheme’s own 2.5 eligibility floor. They are not monitored performance and must never sit on the same axis as a measured figure.
Contains public sector information from the Department for Energy Security and Net Zero (RHI deployment statistics, Ofgem data), licensed under the Open Government Licence v3.0. Licensed under the UK Open Government Licence (OGL).
Frequently asked questions
What is a COP?
The coefficient of performance: units of heat delivered for each unit of electricity used. A COP of 4 means four kilowatt-hours of heat from one kilowatt-hour of electricity. It can exceed one because the delivered heat includes energy moved from outside; it is not the same measure as combustion efficiency.
Why is there no overall average on this page?
Because the monitored systems did not all measure the same thing. Some metered the whole system, others only part of it, and a COP that excludes some of the electricity a system draws reads higher than one that includes it. Averaging across those arrangements produces the single number everyone wants and it does not mean anything, so the figures stay grouped by what was actually measured.
Do these figures apply to my house?
Not directly. These are households who chose to publish their monitoring, which selects for people who are interested in getting it right — well-specified installations, often carefully commissioned. Read them as what a heat pump can achieve in a British home rather than what an average installation does.
Why is hot water so much worse than heating?
In the current self-selected, whole-system-metered sample, median room-heating COP is 4.22 across 262 systems and hot-water COP is 3.08 across 241. Hot-water production generally uses a higher water temperature, but this observational read does not isolate the cause of the gap.
Do heat pumps stop working in cold weather?
No. In the volunteer Electrification of Heat trial's daily dataset, the measured ratio was 2.24 in -5°C to -2.5°C and peaked at 3.04 in 7.5°C to 10°C. This is the heat pump's metered heat divided by whole-system electricity, not a market-wide efficiency rate.
