Heat pump running costs in the UK
Running costs depend on three things: how much heat your home needs, the heat pump's SCOP, and your electricity tariff. Get those right and a heat pump beats a gas boiler on running cost. Get them wrong and it can be more expensive.
The running-cost formula
Annual running cost = (Heat demand kWh ÷ SCOP) × Electricity price £/kWh
The three inputs:
- Heat demand: how much heat your home needs in a year, in kWh. A typical 3-bed UK semi is 11,000–14,000 kWh. An older detached house can be 18,000–22,000.
- SCOP: the heat pump's annual efficiency. Realistic UK ASHP installs are 3.0–4.0.
- Electricity price: standard variable rate per the current Ofgem cap is around 24.5 p/kWh. Time-of-use heat-pump tariffs can drop the effective average to 15–20 p.
Worked examples
Example 1: Well-insulated 3-bed semi
- Annual heat demand
- 11,000 kWh
- SCOP
- 3.8
- Electricity (standard cap)
- 24.5 p/kWh
- Annual running cost
- £710
On a heat-pump tariff at an effective 18 p/kWh, this drops to £520/year.
Example 2: Average UK 3-bed semi
- Annual heat demand
- 13,000 kWh
- SCOP
- 3.3
- Electricity
- 24.5 p/kWh
- Annual running cost
- £965
Example 3: Older 4-bed detached, partial retrofit
- Annual heat demand
- 18,000 kWh
- SCOP
- 2.9
- Electricity
- 24.5 p/kWh
- Annual running cost
- £1,520
This is the case where running costs can underwhelm. SCOP under 3.0 is a sign the system is fighting the property — radiators too small, flow temperatures too high, or insulation gaps. Often fixable.
Tariffs that genuinely help
UK suppliers now offer tariffs specifically priced for heat pump owners. The headline rate is often slightly higher than standard, but the off-peak hours are much cheaper, and most heating energy is consumed when you can schedule the cylinder reheat:
- Octopus Cosy — three rate bands; ~13 p in off-peak windows that the heat pump can target.
- OVO Heat Pump Plus — flat heat-pump-only rate.
- EDF Heat Pump tracker — fixed rate dedicated to heat pump use.
Compare these against the standard cap each quarter; the gap moves.
The SCOP lever
SCOP is the single biggest factor inside your control. Improving SCOP from 3.0 to 3.8 cuts running cost by ~25%. Ways to improve SCOP:
- Lower the design flow temperature — every 5 °C reduction is worth ~10% on SCOP.
- Bigger radiators in the rooms that struggle.
- Weather compensation correctly tuned.
- Set the cylinder thermostat to 45–48 °C (with weekly Legionella cycles to 60 °C).
"Should I run it 24/7 or use a schedule?"
Heat pumps prefer steady, low-temperature output. For most homes, a gentle setback at night (1–2 °C below daytime target) and a continuous low-temperature run during the day will be more efficient than a deep timer-based schedule. The exact answer depends on insulation; many installers will recommend "set it and forget it" with weather compensation doing the work.
What heat pumps cost to run vs gas boilers
On the same 13,000 kWh heat demand, an 88%-efficient gas boiler uses ~14,800 kWh of gas at 6.0 p/kWh (current cap) for an annual cost of £890. The heat pump at SCOP 3.3 costs £965 on standard cap, £660 on a heat-pump tariff. The gap moves with energy prices — gas/electric ratios have widened and narrowed several times since 2021.
See our full heat pump vs gas boiler comparison for a 15-year total cost view.
Related
Heat pump vs gas boiler · Install costs · How heat pumps work