What Does Air Conditioning Usually Cost to Run?
For most modern fixed systems, the real running cost is often lower than people expect. Once a room reaches temperature, the system normally reduces its power draw and only uses the energy needed to maintain comfort.
In simple terms, many home air conditioning systems will often spend much of their time drawing well under 1 kW once they are up and running properly. That is why the hourly running cost is usually measured in pence per hour, not pounds per hour.
HOW TO WORK OUT RUNNING COST
The Simple Formula
The basic way to estimate running cost is:
Electrical input in kW × electricity price per kWh = running cost per hour
Using the current Ofgem average electricity rate of 24.67p per kWh, the running cost works out like this:
- 0.3 kW draw = about 7p per hour
- 0.5 kW draw = about 12p per hour
- 0.7 kW draw = about 17p per hour
- 1.0 kW draw = about 25p per hour
- 1.5 kW draw = about 37p per hour
These examples use the electricity unit rate only, which is the part that changes when the air conditioning is running. The standing charge is separate and would normally be paid whether the system is on or not. Ofgem’s published daily electricity standing charge for the same period is 57.21p per day.
EXAMPLE RUNNING COSTS BY COMMON SYSTEM SIZE
What Different Size Systems Might Cost to Run
To give a more practical benchmark, the examples below use one current wall-mounted single-split range and show the nominal cooling input for each size. That matters because the system size in kW is the cooling output, not the exact electricity it draws from the mains. The examples below are based on the current Ofgem average electricity unit rate of 24.67p per kWh and assume 8 hours of use per day.
2.0 kW system
Using Panasonic’s KIT-TZ20-WKE, the nominal cooling capacity is 2.0 kW and the nominal cooling input is 0.49 kW. At the current Ofgem electricity rate, that works out at about 12p per hour, around £0.97 for 8 hours, and about £29.01 for 30 days at 8 hours per day.
3.5 kW system
Using Panasonic’s KIT-TZ35-WKE, the nominal cooling capacity is 3.5 kW and the nominal cooling input is 0.98 kW. At the current Ofgem electricity rate, that works out at about 24p per hour, around £1.93 for 8 hours, and about £58.02 for 30 days at 8 hours per day.
5.0 kW system
Using Panasonic’s KIT-TZ50-WKE, the nominal cooling capacity is 5.0 kW and the nominal cooling input is 1.60 kW. At the current Ofgem electricity rate, that works out at about 39p per hour, around £3.16 for 8 hours, and about £94.73 for 30 days at 8 hours per day.
Important note:
These figures are useful as a like-for-like guide, but real running costs can still be lower or higher depending on the room, the temperature setting, the insulation level, the amount of sunlight, and how hard the system is working. The Panasonic examples above are model-based worked examples, not a fixed rule for every system on the market.
DAILY AND MONTHLY EXAMPLES
What That Looks Like in Real Use
If your system averages around 0.7 kW while running, that works out at about:
- £1.38 for 8 hours of use
- £41.45 for 30 days at 8 hours per day
If your system averages around 1.0 kW, that works out at about:
- £1.97 for 8 hours of use
- £59.21 for 30 days at 8 hours per day
If your system averages around 1.5 kW, that works out at about:
- £2.96 for 8 hours of use
- £88.81 for 30 days at 8 hours per day
These examples are calculated using Ofgem’s published average electricity unit rate for 1 April to 30 June 2026.
WHAT CHANGES THE RUNNING COST?
Why Running Costs Vary from One Home to Another
The biggest factors are usually:
- Room size
- How hot the room gets in the first place
- Insulation levels
- Sunlight and glazing
- Thermostat setting
- How long the system runs each day
- How well the system is matched to the room
A correctly sized system in a well-insulated room will usually cost less to run than a unit constantly fighting against poor insulation, too much solar gain or a room that is too large for the setup.
HOW TO KEEP RUNNING COSTS DOWN
Simple Ways to Reduce the Bill
The best ways to reduce running costs are usually straightforward:
- Set the temperature to a sensible comfortable level rather than overcooling the room
- Keep doors and windows closed while the system is running
- Reduce direct sunlight with blinds or curtains where possible
- Use timers so the system runs when you actually need it
- Keep filters clean
- Make sure the system is properly sized for the room
In most cases, a well-installed system used sensibly will be far more efficient than people expect.
IS AIR CONDITIONING EXPENSIVE TO RUN IN THE UK?
Usually Less Than People Think
For a lot of homeowners, the answer is no — not when the system is correctly sized and used properly. A bedroom, home office, garden room or loft room can often be kept comfortable for a relatively modest hourly running cost, especially once the room has already reached temperature.
The biggest mistake is usually judging running cost from the unit size alone, rather than from the actual electrical draw during use.
FAQ (Frequently Asked Questions)
How much does air conditioning cost to run per hour in the UK?
Using Ofgem’s published average electricity unit rate of 24.67p per kWh for 1 April to 30 June 2026, a system drawing 0.5 kW costs about 12p per hour, 0.7 kW about 17p per hour, and 1.0 kW about 25p per hour.
How much does it cost to run air conditioning all day?
It depends on the actual electrical draw. At 0.7 kW, 8 hours is about £1.38. At 1.0 kW, 8 hours is about £1.97. At 1.5 kW, 8 hours is about £2.96. These examples are based on Ofgem’s published rate for the 1 April to 30 June 2026 period.
How much do different size systems cost to run?
As a worked example using current Panasonic single-split wall-mounted systems and Ofgem’s current electricity rate, a 2.0 kW system comes out at about £0.97 for 8 hours, a 3.5 kW system about £1.93 for 8 hours, and a 5.0 kW system about £3.16 for 8 hours. These are model-based examples, not a fixed rule for every unit on the market.
Is a bigger air conditioner always more expensive to run?
Not necessarily. What matters most is the actual power draw during use and whether the system is correctly matched to the room.
What makes the running cost go up most?
The main things are room size, heat gain, thermostat setting, insulation, runtime and whether the system is properly sized for the space.
Does air conditioning cost more in very hot rooms?
Yes. Rooms with lots of glazing, poor insulation or strong solar gain will usually make the system work harder and use more electricity.
How can I keep running costs down?
Use a sensible set temperature, reduce heat gain, keep filters clean, and make sure the system is correctly sized and installed for the room.