A typical 3-bedroom semi in the UK uses around 3,750 kWh of electricity a year to run an air source heat pump, which costs about £990. A 1-bed flat uses closer to 1,900 kWh (around £500) and a 4-bed detached house around 5,600 kWh (around £1,475). How much electricity your own heat pump uses comes down to three things: your heat demand, the efficiency of the unit, and the flow temperature the system runs at.
All figures on this page use the Ofgem price cap for 1 October to 31 December 2026: 26.32p per kWh for electricity and 7.97p per kWh for gas.
How a Heat Pump Uses Electricity to Make Heat
A gas boiler burns fuel to create heat. A heat pump works differently: it uses electricity to move heat that already exists in the outside air or the ground into your home. That is why heat pumps deliver far more heat energy than the electricity they consume, and why comparing them to electric radiators is misleading.
There are two types in UK homes. Air source heat pumps extract heat from outdoor air and account for the vast majority of installations. Ground source heat pumps draw heat from buried pipework, cost more to install, and benefit from a stable ground temperature all year.
Electric resistance heating runs at a fixed 1:1 ratio: one unit of electricity gives one unit of heat. Air source heat pumps typically deliver 3 to 4 units of heat per unit of electricity, so they use roughly a quarter to a third of the electricity for the same heating output.
COP, SCOP and SPF: The Numbers That Matter in the UK
COP (Coefficient of Performance) is the instantaneous ratio of heat out to electricity in. A COP of 3.5 means 3.5 kWh of heat for every 1 kWh of electricity consumed. COP changes constantly with outdoor temperature.
SCOP (Seasonal COP) averages that performance across a full heating season and is the figure quoted on UK datasheets. SPF (Seasonal Performance Factor) is what your installation actually achieves once real radiators, pipework and controls are involved, and it is almost always lower than the headline SCOP.
Ignore SEER and HSPF. Those are North American ratings and they do not appear on UK paperwork. For estimating electricity consumption in a British home, SCOP is the number to use.
How Much Electricity Does a Heat Pump Use per Year?
The calculation is straightforward: annual heat demand in kWh divided by SCOP gives annual electricity usage.
A reasonably insulated 3-bed semi needs around 12,000 kWh of heat a year for heating and hot water. At a realistic SCOP of 3.2 that works out at 3,750 kWh of electricity. For context, Ofgem puts typical household electricity use at 2,500 kWh a year, so a heat pump roughly doubles or triples the electricity on your meter while removing the gas bill entirely.
Heat Pump Running Costs by House Size
| Property | Annual heat demand | Electricity used (SCOP 3.2) | Annual cost at 26.32p |
|---|---|---|---|
| 1-bed flat | 6,000 kWh | 1,875 kWh | £494 |
| 2-bed terrace | 9,000 kWh | 2,813 kWh | £740 |
| 3-bed semi | 12,000 kWh | 3,750 kWh | £987 |
| 4-bed detached | 18,000 kWh | 5,625 kWh | £1,481 |
These heat pump running costs assume an average property of each size. A poorly insulated house can need 40% more electricity, while a home with underfloor heating running at a low flow temperature can need 20% less. Add the electricity standing charge of 54.83p a day, roughly £200 a year, which applies whatever heating system you have.
Daily, Monthly and Hourly Costs
Annual averages hide the seasonal swing. A 3-bed semi might draw 25 kWh on a cold January day, costing £6.58, and 7 kWh on a mild October day, costing £1.84. Quoting one daily figure for the whole year tells you very little.
By month, January and February each account for roughly a fifth of annual electricity consumption. For the 3-bed example that is around 700 kWh, or £184 a month at the capped rate. July might cost under £30.
Hourly figures are the least useful measure, but people ask: a heat pump drawing 3 kW costs about 79p an hour to run. In practice a correctly sized unit modulates down and rarely draws its full rated power.
Heat Pump vs Gas Boiler: The 2026 Comparison
A gas boiler running at 85% efficiency turns 7.97p of gas into one kWh of heat, at a cost of 9.4p. A heat pump produces that same kWh of heat for 26.32p divided by its SCOP.
That gives a clean break-even point: above a SCOP of about 2.8, a heat pump costs less to run than a gas boiler. Most modern air source heat pumps commissioned to a sensible flow temperature achieve 3.0 to 3.8, so running costs land below gas in the majority of properties.
Worked through for the 3-bed semi: 12,000 kWh of heat from a gas boiler needs about 14,100 kWh of gas, costing £1,125. The heat pump costs £987. Removing gas also removes the gas standing charge of 29.68p a day, taking a further £108 a year off your energy bills.
Two policy changes matter here. VAT has been removed from domestic electricity between 1 October 2026 and 31 March 2027, and the gas-to-electricity unit price ratio has fallen from 3.6 to 3.3. Both have shifted the economics towards heat pumps and away from gas boilers.
Hot Water: Around a Quarter of Total Consumption
Hot water typically accounts for 20 to 30% of a heat pump's total electricity usage. Producing hot water needs a higher flow temperature than space heating, so the COP during a cylinder reheat drops to roughly 2.2 to 2.8.
Set the cylinder to 48-50°C rather than 60°C, keep the weekly legionella cycle enabled, insulate the primary pipework, and schedule reheats for off-peak hours if you are on a time of use tariff.
How Outdoor Temperature Changes Electricity Consumption
Outdoor temperature is the biggest day-to-day variable. At an outside temperature of 7°C an air source heat pump might run at a COP of 3.5 to 4.0. At -7°C the same unit can fall to 2.2 to 2.5, so it draws more electricity for identical heat output.
Defrost cycles add to this. When the outdoor coil ices up the unit briefly reverses to clear it, which costs energy. Modern controls keep this to a minimum, but in damp cold weather defrosting can add a few percent to electricity usage.
Air Source vs Ground Source Heat Pumps
Air source heat pumps are cheaper to install and perform well in the mild UK climate, but their heating efficiency tracks the weather. Ground source heat pumps draw from soil that stays close to 10°C year round, so they hold a higher SCOP through winter and use less electricity in the coldest weeks.
The trade-off is capital cost and space, since ground source heat pumps need boreholes or a large trench field. For most UK homes the sums favour air source. For rural properties with land and a high heat demand, ground source can pay back.
Flow Temperature: The Biggest Single Lever
Nothing you can change after installation affects heating efficiency more than flow temperature, the temperature of the water sent to your radiators. Typical SCOP by flow temperature:
- 35°C (underfloor or oversized radiators): around 4.0
- 45°C (correctly sized radiators): around 3.3
- 55°C (existing boiler-sized radiators): around 2.7
Dropping from 55°C to 45°C cuts electricity consumption by roughly 18% for the same heat. That usually means upsizing radiators in a few rooms, which costs far less than the electricity it saves over a decade.
Weather compensation goes further by varying flow temperature automatically against outdoor temperature, so the system only runs hot on the coldest days. If your installer left it disabled, switching it on is free efficiency.
Short Cycling and Minimum System Volume
An oversized heat pump in a system holding too little water reaches target temperature, shuts down, cools, and restarts over and over. This short cycling is one of the most common reasons a heat pump uses more electricity than its datasheet suggests, because every start costs energy and the compressor never settles into efficient modulation.
As a rule of thumb, allow 10 to 12 litres of system volume per kW of output. An 8 kW unit wants 80 to 100 litres, and a typical radiator circuit holds well under that. A buffer cylinder or volumiser makes up the difference: the Buffer Cylinder / Volumiser VOLANO TERMICO PDC 25l suits most domestic systems, while larger installations or those needing longer defrost protection use the 50l version.
Heat Pump Tariffs and Solar Panels
Standard variable tariffs are the most expensive way to run a heat pump. Several UK suppliers now offer dedicated heat pump tariffs with cheaper off-peak units, which can cut running costs by 20 to 30% if hot water and thermal storage are scheduled into those windows.
Solar panels help less than people expect, because heat demand peaks in December when solar output is at its lowest. Across a year, solar panels might cover 10 to 20% of heat pump electricity usage. Adding a battery and a smart tariff improves that considerably.
The Boiler Upgrade Scheme
The Boiler Upgrade Scheme does not change running costs, but it changes the heat pump cost you pay up front. In England and Wales the grant is £7,500 towards an air source or ground source heat pump, £2,500 towards air-to-air, and £5,000 towards a biomass boiler.
Homes off the gas grid currently running on oil or LPG can claim £9,000 for applications made between 21 July 2026 and 31 March 2027. Work must be carried out by an MCS-certified installer, who applies for the grant and deducts it from your invoice.
Why Is My Electricity Bill So High With an Air Source Heat Pump?
Unexpectedly high electricity bills after installation almost always trace back to a short list of causes:
- Flow temperature left too high. The commonest fault by far. A system running at 55°C where 45°C would do costs about a fifth more.
- Backup immersion heater doing the work. Resistance heating runs at COP 1. A control fault that leaves it enabled can double consumption.
- Short cycling caused by an oversized unit or insufficient system volume.
- Poor insulation pushing heat demand beyond the design figure.
- The wrong comparison. Electricity costs more per unit than gas, so a bigger electricity bill does not mean higher total energy bills once the gas bill has gone.
- A standard tariff rather than a dedicated heat pump tariff.
If the numbers look wrong, ask your installer for the design flow temperature and the room-by-room heat loss calculation, then compare them against what the system is actually doing.
How to Cut Your Heat Pump Running Costs
- Lower the flow temperature as far as comfort allows and enable weather compensation.
- Let the system run continuously at low output rather than in short boosts. Heat pumps are least efficient when recovering a cold house quickly.
- Check system volume and fit a buffer or volumiser if the unit is cycling.
- Set the cylinder to 48-50°C and reheat off-peak.
- Switch to a heat pump tariff.
- Improve loft and cavity insulation before spending on the heat pump itself.
- Service annually and keep the outdoor unit clear of leaves and debris.
Frequently Asked Questions
Do heat pumps use a lot of electricity?
A heat pump roughly doubles or triples a household's electricity usage, typically adding 1,900 to 5,600 kWh a year. It also removes the gas bill completely, and because it produces 3 to 4 units of heat per unit of electricity, total energy costs usually fall rather than rise.
How much does a heat pump cost to run per month?
For a 3-bed semi, about £82 a month averaged over the year. The spread is wide: roughly £184 in January and under £30 in July. Larger or poorly insulated homes should budget more.
What is the downside of having a heat pump?
The main drawbacks are installation cost, the space needed for an outdoor unit and a hot water cylinder, and the fact that existing radiators often need upsizing to run efficiently at a low flow temperature. Performance depends heavily on the quality of the design and commissioning.