What does air conditioning cost to run in a business?

How do you work out what air conditioning costs to run?

Multiply the cooling the system delivers over a year by the price of a kilowatt hour, after dividing by its seasonal efficiency. In four steps:

1. Take the rated cooling output in kW from the unit's data plate or product data.
2. Estimate the equivalent full-load hours: the hours at full output that would deliver the same cooling as the real, mostly part-load, running.
3. Multiply output by those hours, then divide by the SEER. The result is electricity in kWh.
4. Multiply the kWh by the unit rate in pence per kWh.

SEER is the seasonal energy efficiency ratio. The ecodesign rules define it as the reference annual cooling demand divided by the annual electricity consumption for cooling, so a SEER of 4.6 means about 4.6 kWh of cooling for each 1 kWh of electricity over a season.

Those rules cover mains-powered air conditioners of 12 kW cooling capacity or less. Larger cooling products, up to 2 MW, fall under a separate regulation that states minimum seasonal efficiency as a percentage, as the chiller cost guide explains, so for VRF take the seasonal figure from the product data. The guide to SEER and efficiency shows how to read it.

Which electricity price should a business use?

Use the unit rate on your own contract. For a published benchmark, DESNZ reports the average electricity price for non-domestic users across all size bands as 24.3p per kWh for 2025 (provisional), in nominal terms and including the Climate Change Levy.

DESNZ notes that businesses differ greatly in energy consumption and that prices change with consumption level, so treat it as an average, not a quote. The price also moves from year to year. The table applies each annual average to the same 7,111 kWh, the 40 kW VRF example below at 800 full-load hours.

Year	DESNZ average, non-domestic electricity	Cost of 7,111 kWh
2022	20.9p per kWh	£1,486
2023	27.2p per kWh	£1,934
2024	26.3p per kWh	£1,870
2025 (provisional)	24.3p per kWh	£1,728

The 2023 average was about 30% above 2022, which on this load is nearly £450 a year from the tariff alone.

What do three worked examples come to?

The tables price three illustrative systems at 24.3p per kWh. This is arithmetic to show the method, not a quote or a measurement: the systems, SEER values and hours are assumptions. The input is rated cooling divided by the SEER; the hourly cost assumes full rated cooling for that hour.

System	Rated cooling	SEER assumed	Input implied by the SEER	Cost per hour	Cost per 24 hours
Wall split	3.5 kW	4.6	0.76 kW	18p	£4.44
Ceiling cassettes	10 kW	4.3	2.33 kW	57p	£13.56
VRF system	40 kW	4.5	8.89 kW	£2.16	£51.84

The first two SEER values are the lowest the ecodesign rules allow on the market for units under 6 kW, and of 6 to 12 kW, using a refrigerant with a global warming potential above 150, so a better unit would cost less. VRF above 12 kW sits outside that regulation, so 4.5 is an assumption. Twenty-four hours at full output is a ceiling, because real systems modulate.

The annual figures depend on equivalent full-load hours. These three levels are labelled assumptions, not benchmarks.

System	350 hours	800 hours	1,600 hours
Wall split, 3.5 kW	£65 (266 kWh)	£148 (609 kWh)	£296 (1,217 kWh)
Ceiling cassettes, 10 kW	£198 (814 kWh)	£452 (1,860 kWh)	£904 (3,721 kWh)
VRF system, 40 kW	£756 (3,111 kWh)	£1,728 (7,111 kWh)	£3,456 (14,222 kWh)

Why do hours of use matter more than the make of unit?

Because the efficiency figure on a datasheet is built on a fixed number of hours that has little to do with a business. The regulation defines the equivalent active mode hours for cooling as an assumed annual number, and its table sets 350 hours a year for an air conditioner that only cools. The 350-hour column above uses that test figure; a shop or office that cools for several times as long should apply its own hours to the SEER, as the other columns do.

For scale, a building used 10 hours a day, five days a week, for 52 weeks is occupied for 2,600 hours. Equivalent full-load hours are those occupied hours multiplied by the average share of full output the system actually delivers.

Take the 10 kW example at 800 hours, which costs £452 a year. Doubling the hours doubles it to £904. A real seasonal efficiency 20% below the SEER used raises it to £565, a rise of a quarter. Occupancy and cooling load move the answer more than the badge on the outdoor unit.

What else changes the bill in a working building?

• Controls and settings. The government's guide to air conditioning inspections says the energy assessor reports on the adequacy of the installed controls and control settings, and that heating and cooling can run together unnecessarily because of inappropriate control or settings. The guide to office air conditioning controls covers setpoints and scheduling.
• Temperature targets. HSE says businesses must ensure workplace temperatures are reasonable. A tighter target means more cooling hours, so the setpoint is a cost decision as well as a comfort one.
• Condition of the plant. The same inspection looks at the adequacy of equipment maintenance. How servicing is priced is set out on the air conditioning servicing cost page.

How can you check the figure for your own building?

1. List each system's rated cooling output and declared seasonal efficiency from the product data.
2. Take the unit rate from your latest contract.
3. Test three hour assumptions, as in the table, and see which fits your occupancy and the weeks the plant works hardest.
4. Add the other recurring items: servicing, refrigerant leak checks and, above 12 kW, the inspection report.

On the last point, the inspection duty applies above 12 kW of effective rated output, including sets of smaller units whose combined output passes 12 kW. The TM44 guide explains it, and the savings calculator gives a first-pass estimate. What drives the price of the equipment and its installation is covered in the commercial air conditioning cost guide. A site-specific figure comes from a load calculation and survey, and you can send an enquiry through the form on this site.

Sources

• DESNZ annual report and accounts 2025 to 2026: performance report, GOV.UK, updated 19 August 2026, checked 22 October 2026
• Commission Regulation (EU) No 206/2012, Annex I, legislation.gov.uk, checked 22 October 2026
• Commission Regulation (EU) No 206/2012, Annex II, legislation.gov.uk, checked 22 October 2026
• Commission Regulation (EU) No 206/2012, Article 1, legislation.gov.uk, checked 22 October 2026
• Commission Regulation (EU) 2016/2281, Article 1, legislation.gov.uk, checked 22 October 2026
• Commission Regulation (EU) 2016/2281, Annex II, legislation.gov.uk, checked 22 October 2026
• A guide to air conditioning inspections in buildings, MHCLG, GOV.UK, updated 18 September 2024, checked 22 October 2026
• Ventilation in the workplace: keeping a comfortable temperature, Health and Safety Executive, checked 22 October 2026

Frequently asked questions

How much does it cost to run an air conditioner for 24 hours?

At full output for 24 hours, the three worked examples cost £4.44 (3.5 kW split), £13.56 (10 kW of cassettes) and £51.84 (40 kW VRF) at 24.3p per kWh. That is a ceiling. Systems modulate, so the real figure is normally lower.

Is air conditioning expensive to run in the UK?

It depends on the hours and the load. At 800 full-load hours and 24.3p per kWh, the 3.5 kW example comes to about £148 a year and the 40 kW VRF example to about £1,728. Weigh that against the value of working or trading comfortably on the hottest days, and against servicing and inspection costs.

Should a business use the 2025 average or its own tariff?

Its own tariff. The DESNZ figure is a provisional all-size-band average for 2025, useful for a first estimate and for seeing how far prices have moved. Your contract rate and meter data decide what you actually pay.

Does a higher SEER always mean a lower bill?

For the same cooling and the same hours, yes: electricity falls in proportion to SEER, so a SEER 10% higher uses about 9% less. The saving is lost if the system is oversized, badly controlled or run for longer than the building needs.