Costs and running · 6 min read
The Cheapest Way to Run Air Conditioning at Home
Most households could cut their cooling bill by a third without noticing the difference in comfort. Here is how.
Published 2026-07-20 · Updated 2026-07-20 · WDI Group (Surrey) Ltd
Get the set point right
Cooling to 18°C on a 30°C day is expensive and often uncomfortable — you end up cold in one room and hot everywhere else. Set 23–24°C and let the unit hold it. Once humidity drops, that feels considerably cooler than the same temperature outdoors.
In heating, the same logic applies in reverse: 20–21°C held steadily beats blasting 26°C for twenty minutes.
Run steady rather than in bursts
Inverter systems are cheapest when they are modulating gently. Turning the unit off for two hours and then dragging the room back down forces the compressor to full output, which is the expensive part of the cycle.
If you will be back within a couple of hours, leaving it running at a modest set point usually costs less.
Help the building do some of the work
Close blinds and curtains on sun-facing windows before the room heats up, not after. Keep doors closed so the unit conditions the space it was sized for. Ventilate at night when the outside air is cooler than inside.
These are free, and they shorten the time the compressor spends working hard.
- Shade south and west glass during the day
- Close internal doors to the conditioned room
- Purge heat overnight with open windows when it is cooler outside
- Keep the outdoor unit clear of plants, bins and fencing
Clean filters and a serviced system
A clogged filter chokes airflow, so the unit runs longer for the same result. Rinsing the filters monthly in season takes five minutes and is the highest-return maintenance job there is.
An annual service keeps refrigerant charge, coil condition and drainage right, all of which affect efficiency as well as reliability.
Match it to your tariff
If you are on a time-of-use tariff or have solar, pre-cool during cheap or self-generated hours and let the building coast through expensive periods. Timers and scheduling on the controller make this automatic.
This one change can outweigh every other tip on this list.
Frequently asked questions
- Is a smart controller worth it?
- If you will actually use scheduling and geolocation, yes. If you set it once and forget it, the built-in timer does most of the job.
- Does dry mode save money?
- In humid weather it can, because removing moisture makes a room feel cooler without dropping the temperature as far.