Glossary · Air conditioning
How much does air conditioning cost to run?
Air conditioning running costs are the electricity charges for operating a unit. You work them out by multiplying the unit's power draw in kilowatts by the hours it runs and by your price per kilowatt hour. Inverter models, room size, insulation and the temperature you set all change the result.
Key points
- The sum is kW multiplied by hours multiplied by your unit rate. Check your own tariff, because rates differ by region.
- Ofgem's price cap from 1 October to 31 December 2026 averages 26.32p per kWh for electricity paid by Direct Debit, with no VAT on electricity.
- Bosch's example puts a split unit at about 220 kWh for 30 days at 8 hours a day. At 26.32p that is about £57.90.
- In Bosch's example a portable unit costs about 1.5 times as much to run as a fixed split unit.
- Daikin says inverter units use up to 30% less power than non-inverter units.
How air conditioning running costs work
The cost of running an air conditioner is an electricity bill like any other. The sum has three parts: the power the unit draws in kilowatts (kW), the hours it runs, and your price per kilowatt hour (kWh).
Bosch says running costs depend on the electricity price, power consumption, usage time and the efficiency of the unit.[2]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts Energy use also depends on room size, insulation and how you use the unit.[2]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts
For the price, use the unit rate on your own bill. As a guide, Ofgem says that from 1 October to 31 December 2026 the price cap averages 26.32p per kWh for electricity paid by Direct Debit. This is an average across England, Scotland and Wales, and it does not include VAT, because the government has removed VAT from electricity bills from 1 October 2026 to 31 March 2027.[1]Ofgem, Changes to energy price cap between 1 October and 31 December 2026 If you are on a fixed tariff, the cap does not apply to you.[1]Ofgem, Changes to energy price cap between 1 October and 31 December 2026
What changes the bill
| Factor | Effect on cost |
|---|---|
| Inverter or fixed speed | Inverter units change compressor speed instead of switching on and off |
| Unit type | Fixed split units cost less to run than portable units in Bosch’s example |
| Room and insulation | Bigger or leakier rooms need more cooling |
| Temperature setting | Bosch suggests keeping the room about 6 °C below the outside temperature, not colder |
| Own solar power | Bosch says using your own solar power reduces the cost |
Daikin explains that a non-inverter unit has one operating mode, so it controls temperature by stopping and starting. Power use spikes at each restart, which pushes the average up.[3]Daikin UK, What is inverter technology? An inverter changes the compressor speed, and Daikin says this means 30% less power consumption.[3]Daikin UK, What is inverter technology? The result you get will depend on your home and use. See inverter air conditioner for more, and SEER for the seasonal efficiency rating.
Bosch suggests limiting the room temperature to about 6 °C below the outside temperature, and says using your own solar power reduces the cost of running the unit.[2]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts
On unit type, Bosch’s example puts a portable air conditioner at about 102 euros against about 68 euros for a permanently installed split unit under similar conditions.[2]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts That is roughly one and a half times as much. Compare the types in portable vs split air conditioner.
Example
Bosch’s own example is a permanently installed split unit running for 30 days in summer at 8 hours a day. It says that uses approximately 220 kWh.[2]Bosch Home Comfort, Bosch air conditioners and climate control units: key facts That is 240 hours, so the unit averages about 0.9 kW.
At Ofgem’s average rate of 26.32p per kWh:
- 220 kWh at 26.32p comes to about £57.90 for the month.
- Per hour, 0.9 kW at 26.32p comes to about 24p.
- Per 8-hour day, that is about £1.93.
Priya in Leeds could swap in her own unit rate and her own hours. If she runs it for 4 hours a day instead of 8, the monthly figure halves. Bosch’s 220 kWh is an example calculation from a manufacturer, not a measured result for any particular home. Her actual bill will differ.
What people get wrong
Many people look only at the cooling capacity printed on the unit and assume that is the power it draws. Capacity and power input are different numbers. Check the power input on the spec sheet, then multiply by your own tariff.
Another mistake is to compare a unit’s maximum draw with a rival’s average. Inverter units vary their output, so the fair comparison is average running over a typical day.
The bottom line
Running an air conditioner costs kW multiplied by hours multiplied by your unit rate. Using Bosch’s example and Ofgem’s average rate, a fixed split unit running 8 hours a day for 30 days costs about £58. Inverter models and fixed split units cost less to run than the alternatives in the manufacturers’ own examples. Work out your own figure from the spec sheet and your bill.
Common questions
How do I work out what my air conditioner costs per hour?
Take the unit's average power draw in kW and multiply by your price per kWh. A unit averaging 0.9 kW at 26.32p per kWh costs about 24p an hour. Inverter units vary their draw, so use the average, not the maximum.
Is an inverter air conditioner cheaper to run?
Daikin says inverter models use up to 30% less power than non-inverter models, because the compressor changes speed instead of switching on and off. The saving in your home depends on how you use it.
Does a portable air conditioner cost more to run than a split unit?
In Bosch's own example calculation, yes. The fixed split unit came to about 68 euros for the period and the portable unit about 102 euros. That is about 1.5 times as much.
What electricity price should I use?
Use the unit rate on your own bill. For a guide, Ofgem's price cap average from 1 October to 31 December 2026 is 26.32p per kWh for Direct Debit customers, without VAT.
Sources
We cite the original source for every figure: government, regulators, standards bodies and manufacturers' own documents. Each one shows the date we last checked it.
- Ofgem. Changes to energy price cap between 1 October and 31 December 2026. Checked 11 November 2026. ↩
- Bosch Home Comfort. Bosch air conditioners and climate control units: key facts. Checked 11 November 2026. ↩
- Daikin UK. What is inverter technology?. Checked 11 November 2026. ↩