How Much Does Air Conditioning Cost to Run in the UK?
How to work out what air conditioning costs to run in the UK, with worked examples for cooling and heating, what SEER and SCOP mean, and how to keep running costs down.
By Max Tuleberg · Founder, Vento · Last updated 24 October 2026
Founder of Vento. Worked on the tools before building the software.
A modern air conditioner usually costs tens of pounds to run for a UK summer, not hundreds. As a worked example at 25p per kWh, cooling a bedroom on summer nights comes to about £17 for the season, and a living room on summer afternoons about £36. The workings are below so you can swap in your own numbers.
Worked examples
| Scenario | Unit | Use | Efficiency | Electricity used | Cost |
|---|---|---|---|---|---|
| Bedroom, summer nights | 2.5 kW | 6 h/day × 60 days | SEER 6.5 | 69 kWh | £17 |
| Living room, summer afternoons | 3.5 kW | 6 h/day × 90 days | SEER 6.5 | 145 kWh | £36 |
| Living room, winter heating | 3.5 kW | 8 h/day × 150 days | SCOP 4 | 525 kWh | £131 |
Assumptions: an inverter unit averaging 50% of its rated output while running (they rarely run flat out), the efficiency shown, and an example electricity price of 25p per kWh. Check your own tariff — the result scales directly with it.
How the sum works
Running cost = (unit size × average load × hours) ÷ efficiency × electricity price. For the bedroom: 2.5 kW × 0.5 × 6 h × 60 days = 450 kWh of cooling. Divide by a SEER of 6.5 and you buy 69 kWh of electricity, which at 25p is £17.
SEER and SCOP: the numbers that set your bill
- SEER (Seasonal Energy Efficiency Ratio) is cooling efficiency over a season. A SEER of 6.5 means 6.5 units of cooling for every unit of electricity.
- SCOP (Seasonal Coefficient of Performance) is the same idea for heating. A SCOP of 4 means four units of heat per unit of electricity.
A higher number means a cheaper bill. Two units of the same size can differ noticeably in SEER and SCOP, so it's worth asking your installer for both figures when comparing quotes.
Heating with air conditioning
Most modern splits heat as well as cool. In our winter example the 3.5 kW unit delivers 2,100 kWh of heat for about £131 — the same heat from a direct electric heater would cost about £525 at the same price. If the system replaces your existing heating across the whole home, it may also qualify for the £2,500 Boiler Upgrade Scheme grant.
Keeping running costs down
- Choose a unit sized for the room — oversized units cycle on and off and run less efficiently.
- Set cooling to around 21–24°C rather than as low as it goes.
- Close curtains or blinds on sunny windows during the hottest part of the day.
- Keep the filters clean and have the system serviced as the manufacturer recommends.
Want your own figure? Use the running cost calculator with your unit size, efficiency and tariff.
This guide is general information for UK installers, not legal or regulatory advice. Always check the current regulations and manufacturer instructions for your specific job.
Frequently asked questions
How much does air conditioning cost to run in the UK?
Less than most people expect. As a worked example at 25p per kWh, a 2.5 kW bedroom unit used six hours a night for 60 summer nights costs about £17 for the season, and a 3.5 kW living-room unit used six hours a day for 90 days about £36. Your figure depends on the unit's efficiency (SEER), how long you run it and your electricity price.
Is air conditioning cheaper to run than an electric heater?
Much cheaper. In heating mode an air conditioner is a heat pump: with a SCOP of 4 it delivers about 4 units of heat for every unit of electricity. In our winter example the same heat would cost about £131 from the heat pump and about £525 from a direct electric heater at the same 25p per kWh.
How do I work out air conditioning running costs?
Multiply the cooling or heating you need (unit size in kW × average load × hours) by your electricity price, then divide by the unit's efficiency — SEER for cooling, SCOP for heating. The running cost calculator does this for you.
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