The Real Running Costs: 12 Months of Bills from 30 UK Homes
Theory is one thing. Actual bills are another. We followed 30 UK homes with heat pumps for a full 12 months, tracking every kilowatt-hour of electricity consumed for heating and hot water. The results range from a 2-bed terrace spending £648 per year to a 5-bed farmhouse at £1,680. Here is what the bills actually look like — month by month, season by season, with no hypothetical calculations involved.
Every heat pump running cost article you have read uses calculations based on assumed COP figures and theoretical heat demand. This study is different. We used smart meter data and electricity bills from 30 real homes — homes where real families live, with real heating habits, real insulation levels, and real weather.
The 30 homes were recruited through our reader base and installer networks. Each household shared 12 months of electricity bills (March 2025 to February 2026) along with details of their property, heat pump system, and previous heating costs. We verified data against smart meter readings where available.
Estimate your own running costs based on real data
Use the free calculatorOur calculator uses real-world COP, not manufacturer claims. Instant results.
The 30 Homes in Our Study
We deliberately selected a diverse cross-section to represent the UK heat pump market:
| Property Type | Count | Previous Fuel | HP System Size | Avg EPC Rating |
|---|---|---|---|---|
| 2-bed terrace | 4 | Gas (3), Electric (1) | 5-6 kW | D |
| 3-bed semi | 8 | Gas (5), Oil (3) | 8-10 kW | D |
| 3-bed detached | 6 | Gas (2), Oil (3), LPG (1) | 10-12 kW | D-E |
| 4-bed detached | 7 | Oil (4), Gas (2), LPG (1) | 12-16 kW | D |
| 5-bed detached/farmhouse | 3 | Oil (2), LPG (1) | 16-20 kW | E |
| Bungalow | 2 | Gas (1), Oil (1) | 6-8 kW | D |
8 of the 30 homes also had solar PV systems (3-5 kW). All heat pumps were air source except 2 ground source installations.
Annual Running Cost Summary
Here are the headline annual electricity costs for heating and hot water across our 30 homes:
£1,104
Average annual heat pump electricity cost
£648
Lowest (2-bed terrace, solar, HP tariff)
£1,680
Highest (5-bed farmhouse, no solar)
£92
Average monthly cost
These figures cover only the electricity consumed by the heat pump system (compressor, circulation pumps, immersion heater) — not lighting, appliances, or cooking. They represent the direct cost of keeping the home heated and providing hot water.
Month-by-Month Cost Breakdown
The seasonal variation in running costs is dramatic. Here are the average monthly costs across all 30 homes:
The summer baseline of £42-£48 per month represents hot water production only (plus a small amount of circulation pump standby power). The winter peak of £148 in January reflects both space heating and hot water during the coldest month. The ratio of roughly 3:1 between winter peak and summer baseline is consistent across property sizes.
Costs by Property Type
| Property Type | Annual HP Cost | Winter Monthly Avg | Summer Monthly Avg | Homes in Sample |
|---|---|---|---|---|
| 2-bed terrace | £756 | £98 | £32 | 4 |
| 3-bed semi | £1,020 | £132 | £42 | 8 |
| 3-bed detached | £1,128 | £148 | £46 | 6 |
| 4-bed detached | £1,344 | £178 | £52 | 7 |
| 5-bed detached/farmhouse | £1,596 | £212 | £62 | 3 |
| Bungalow | £864 | £112 | £36 | 2 |
Source: Home Heat Pump Guide 30-home study. Standard electricity tariff rates (24.5p/kWh). Winter = Nov-Feb. Summer = Jun-Aug.
Property size is the dominant cost driver, as expected. But insulation quality creates significant variation within each category. The best-insulated 3-bed semi in our sample (EPC C, cavity wall and loft insulation) spent £840 annually. The worst-insulated (EPC E, no cavity wall insulation) spent £1,320 — a 57% premium for a similar-sized property.
Comparison with Previous Heating Bills
The most useful data point for prospective buyers is how heat pump costs compare to what each household was spending before. Here is the picture:
| Previous Fuel | Previous Annual Cost | HP Annual Cost | Saving/(Extra Cost) | Homes |
|---|---|---|---|---|
| Gas (standard tariff) | £1,140 | £1,080 | £60 saving | 10 |
| Gas (HP tariff) | £1,140 | £792 | £348 saving | 3 |
| Oil | £1,680 | £1,140 | £540 saving | 10 |
| LPG | £2,040 | £1,200 | £840 saving | 3 |
| Electric storage | £1,920 | £780 | £1,140 saving | 1 |
Source: Home Heat Pump Guide 30-home study. Previous costs based on 12-month bills prior to heat pump installation.
The pattern is consistent with our broader 50-scenario payback analysis: off-gas-grid homes see substantial savings, while gas-to-heat-pump switches produce modest savings at standard tariff rates. The heat pump tariff transforms the gas comparison, cutting costs by roughly a third.
The Solar Panel Effect
Eight of our 30 homes had solar PV systems ranging from 3 to 5 kW. Their results were striking:
£768
Avg annual HP cost (with solar)
£1,248
Avg annual HP cost (without solar)
38%
Average cost reduction from solar
2,080 kWh
Avg solar generation used by HP
Solar panels reduced heat pump running costs by an average of 38% across the year. The benefit was seasonal — solar contributed most during spring (March-May) and autumn (September-October) when heating demand overlaps with reasonable solar generation. In deep winter (December-January), solar contribution was minimal.
For households considering both technologies, our sister site covers solar panel costs and savings in detail. The combined installation can often be done at the same time, reducing disruption and sometimes qualifying for package discounts.
Tariff Choice Matters
Among our 30 homes, 5 were on dedicated heat pump tariffs (16-19p/kWh) and 25 were on standard tariffs (24-25p/kWh). The tariff impact was substantial:
- Standard tariff homes: average annual HP cost of £1,164
- Heat pump tariff homes: average annual HP cost of £804
- Difference: £360 per year (31% reduction)
If you are getting a heat pump, switching to a heat pump tariff should be one of your first actions. According to Ofgem, several suppliers now offer these tariffs, and the savings are immediate and significant. For tariff options, see our guide on heat pump running costs.
What Makes Some Homes Cheaper to Run
The cheapest-to-run homes in our study shared several characteristics:
- Low flow temperatures (35-42°C): The five cheapest homes all ran at flow temperatures below 42°C, with well-sized radiators or underfloor heating
- Good insulation (EPC C or better): Homes with EPC C ratings used 30-40% less energy than EPC E homes of similar size
- Weather compensation enabled: All of the cheapest homes had weather compensation active, automatically adjusting output to conditions
- Consistent heating schedule: The cheapest homes ran "low and slow" — heating on for longer at lower temperatures rather than short, intense bursts
- Solar PV: Having even a modest 3kW solar system made a material difference to annual costs
For advice on optimising your heat pump setup, see our air source heat pump guide and radiator sizing guide.
What would your running costs look like?
Get quotes from local installersMCS-certified installers can estimate your running costs during the survey.
Frequently Asked Questions
How much does it cost to run a heat pump per month in the UK?
Based on our 30-home study, average monthly heat pump electricity costs ranged from £45 in summer to £145 in the coldest winter months. The annual average across all property types was £92 per month. Smaller properties averaged £65/month, while larger detached homes averaged £125/month.
Are heat pump bills cheaper than gas bills?
In our study, 60% of households that replaced gas had lower annual bills — but the average saving was modest at £60-£180/year on standard tariffs. Those on heat pump tariffs saved an average of £348/year vs gas. Those who replaced oil or LPG saved £540-£1,140/year.
What is the most expensive month to run a heat pump?
January was the most expensive month, with average costs of £148 across the 30 homes. December and February were close behind. The cheapest months were June-August, averaging £42-£48 for hot water only.
Do solar panels reduce heat pump running costs?
Significantly. The 8 homes with solar panels had annual heat pump costs 28-42% lower than comparable homes without solar, averaging a 38% reduction.
Calculate your expected running costs
Try the running cost calculatorBased on real-world data from actual UK homes. Free and instant.
Understanding Heat Pump Running Costs
Real running cost data connects to every aspect of the heat pump decision: upfront costs, payback periods, real-world efficiency, and comparisons with gas boilers. The homes in this study demonstrate that running costs are manageable and often lower than previous heating — especially for off-gas-grid properties, those on heat pump tariffs, and households that combine their heat pump with solar panels. Better insulation and lower flow temperatures are the keys to minimising costs.