Air conditioning · Running costs
What it actually costs to run a modern split in a UK summer.
Primary question · If I install AC, what will it actually do to my electricity bill?
A correctly-sized 2.5 kW split running overnight to maintain a bedroom around 22°C typically averages 200–400 W. At UK rates that's roughly 20–50p per night. Daytime cooling of a larger living room runs higher; but rarely above a few pounds a day, even in a heatwave week.
The five questions
Is this right for me?
Anyone scared of the 'AC = £100 a week' myth.
What will it cost?
20–50p per night for a bedroom. £1–3 per day for a living room in heatwave conditions. Standby draw is negligible.
Advantages
- Cheaper to run than most people imagine
- Inverter modulation keeps low loads efficient
- Reversible; heats cheaply too
Trade-offs
- Costs scale with how cold you run it
- Older units (pre-inverter) are dramatically less efficient
What to do next
Run the AC cost planner to estimate your specific bill impact.
House Summary
Modern inverter splits are a fraction of the running cost most UK homeowners assume. The kettle is more expensive.
Related decisions
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