The price cap rose by £63 on 1 October, the third increase this year. That extra 10% on unit rates hits every appliance plugged into the wall, but portable air conditioners take a disproportionate hit. These units are energy-intensive, inefficient, and increasingly popular as UK summers get hotter.
As reported by Ideal Home, the sums are stark: a typical portable AC unit drawing 1.2 kW and running for 8 hours a day now costs about 80p a day, or £24 a month. That’s £288 a year just for cooling one room.
Who qualifies, and who doesn’t
Every household on a standard variable tariff is affected. Ofgem’s new cap sets electricity at 24.5p per kWh and standing charges at 60.1p a day. That means a 1.5 kW portable AC costs 37p an hour at full blast. For the 1.2 million UK households that bought a portable AC in the past two years, the running cost has jumped by about 8% since July.
But the pain is not uniform. Homes with poor insulation, single-glazed windows, uninsulated loft, draughty doors, need the AC on longer and at higher settings. A 2023 Energy Saving Trust study found that a typical 3-bed semi with EPC band D loses 30% of its cooled air through walls and roof. That means you are paying to cool the street.
What it costs a typical 3-bed semi
Take a 1970s semi in Milton Keynes with EPC band D. The owners run a 1.2 kW portable AC for 8 hours a day during the 90-day cooling season. At the new 24.5p/kWh rate, that’s 29.4p per hour, or £2.35 a day, £211.50 for the summer. Add standing charges and the total is nearer £240.
Compare that to a properly sized air-to-air heat pump, which can cool and heat. Running costs for cooling drop to roughly 10p per hour, or £72 for the same season. The upfront cost is higher, typically £3,000–£5,000 installed, but the Boiler Upgrade Scheme offers £7,500 off heat pump installations, and the EPC improvement from D to C can add 5–10% to house value.
The catch is that portable ACs are often bought in haste during a heatwave, without considering the long-term running costs. The Cooling Britain report from the UK Green Building Council found that 40% of portable AC buyers never check the energy label. Most units are rated F or G.
What you can do now
First, check your unit’s power rating. It should be on the back or in the manual. Multiply by 24.5p to get your hourly cost. Then decide: is cooling one room worth £20 a month?
Second, reduce the load. Draught-proofing costs about £200 and can cut cooling demand by 15%. Reflective window film costs £30 and can reduce solar gain by 70%. Both pay back within one summer.
Third, consider a fixed split-system AC with heat pump functionality. These are three times more efficient than portable units and qualify for the Boiler Upgrade Scheme if installed as a primary heating source. The grant covers up to £7,500, and the system can both heat and cool, effectively replacing a gas boiler and a portable AC.
Households on standard variable tariffs can apply for the Boiler Upgrade Scheme through gov.uk. Applications close on 31 March 2027. For those unable to switch, the Energy Company Obligation (ECO4) scheme offers free insulation and heating upgrades for low-income homes. Check eligibility on the Ofgem website.
Frequently Asked Questions
At the new electricity rate of 24.5p per kWh, a typical 1.2 kW portable AC costs about 29p per hour. A larger 1.5 kW unit costs 37p per hour. Running it for 8 hours a day adds roughly £2.35 to your daily electricity bill.
Yes. An air-to-air heat pump costs about 10p per hour to run for cooling, roughly a third of a portable AC. The Boiler Upgrade Scheme covers up to £7,500 of the installation cost. That makes it a viable long-term investment for homes that need both heating and cooling.
