Portable Air Conditioner Running Costs UK — What You'll Actually Pay
A portable AC costs 25-45p per hour to run at current UK electricity prices (24p/kWh July 2026). That's about £1.50-2.50 for a full night of cooling. Here's the exact breakdown.
Running costs by BTU (at 24p/kWh)
| BTU | Power draw | Cost per hour | 8hr night | 30 days (8hr/day) |
|---|---|---|---|---|
| 7,000 | ~780W | 19p | £1.50 | £45.00 |
| 9,000 | ~1,000W | 24p | £1.92 | £57.60 |
| 12,000 | ~1,350W | 32p | £2.59 | £77.76 |
| 14,000 | ~1,600W | 38p | £3.07 | £92.16 |
Why the compressor doesn't run constantly
Portable ACs cycle the compressor on and off — they don't draw full power continuously. Once the room reaches the set temperature, the compressor slows or stops while the fan keeps running. Real-world usage is typically 60-80% of the rated power over a cooling session. The numbers above assume ~75% duty cycle, which matches real UK usage patterns.
How to reduce running costs
- 🔌 Use a timer or smart plug — run for 2 hours before bed, then switch off. A cool room stays cool for hours
- 🪟 Seal the window properly — a leaky window seal lets hot air in, making the AC work harder
- 🌙 Close curtains during the day — south-facing rooms gain 3-5°C from solar radiation. Blackout curtains pay for themselves
- 🌡️ Set to 22-24°C, not 18°C — every degree lower adds ~8% to running cost. 22°C feels cold when it's 32°C outside
Compare: portable AC vs other cooling
| Device | Cost/hr | Cools room? |
|---|---|---|
| Portable AC 9,000 BTU | 24p | ✅ Yes |
| Tower fan | 1-2p | ❌ No |
| Pedestal fan | 1-2p | ❌ No |
| Dehumidifier | 4-8p | Makes heat feel better |
Calculate your exact running costs →— enter your unit's wattage and your electricity rate.