- Confused.com highlights the most cost effective ways to beat the heat as UK braces for another heatwave
- Running a pedestal fan overnight costs 12p a day, while a portable air conditioning unit costs £2.35 per night
- An installed AC unit costs £3.50 if used continuously overnight - but in reality it costs £1.64 as it cycles down once the room reaches the desired temperature
- Portable AC units have sold out on the high street and online as Tara Evans, Personal Finance Expert for Confused.com, warns about scams and tips for buying fans and AC
As temperatures rise again around the UK and heatwaves become more frequent, Confused.com reveals the most cost-effective ways to heat the soaring temperatures in your home.
New analysis by Confused.com shows heatwaves could add over £200 to bills, on average.
Last year, Heathrow recorded 59 days above 25°C, one of the UK's warmest monitoring locations, using Met Office historical temperature data from 2025.
We calculated the cost of using appliances for nine hours a night, based on 59 nights and it adds up to:
| Cooling option | Estimated annual running cost* |
|---|---|
|
Pedestal fan
|
£7.08
|
|
Portable air conditioner
|
£138.65
|
|
Installed air conditioner (used continuously for 9 hours)
|
£206.50
|
|
Installed air conditioner (1 hour at full power, then 50% output for 8 hours)
|
£96.76
|
The cheapest option remains a standard pedestal fan, costing around 12p a night to run for nine hours.
But for households needing more relief from soaring temperatures, portable air conditioning units are becoming increasingly popular. However, these come at a much higher cost, averaging £2.35 per night.
Installed air conditioning systems can appear even more expensive at first glance, costing around £3.50 if run continuously for nine hours.
But unlike portable units, installed systems don’t typically run at full power all night.
Once a room reaches its target temperature, they cycle down and maintain it at a lower output.
Confused.com estimates an average installed air conditioning unit can cool a medium-sized room from 35°C to 20°C in around 45 minutes to an hour, depending on insulation and room size, before switching to lower power.
That means the realistic overnight running cost falls to around £1.64, making it cheaper than a portable unit over time.
However, while installed systems may be cheaper to run long-term, the upfront costs are significantly higher.
A portable air conditioning unit costs around £300 and can be moved from room to room, while a fixed air conditioning system costs closer to £1,900 to install in one room.
For smaller homes, this may be less of an issue, but for larger households, flexibility could still make portable units the better option.
Tara Evans, personal finance editor at Confused.com, says:"Keeping cool during hot weather can come at a cost, especially if you’re relying on appliances overnight.
As each summer keeps getting hotter and heatwaves feel more intense, many households need to be aware of how much heatwaves are costing them.
While fans remain the cheapest option, as temperatures soar you’re often left feeling hot and bothered and tossing and turning at night.
Installing aircon comes with a chunky up-front cost - but it’s worth considering the pros and cons compared to a portable unit.
An installed air conditioning unit may have a smaller impact on your bills each summer, but it will typically only be effective in one room. A portable unit can be moved between rooms, giving you more flexibility. Installed aircon units usually last for 20 years if maintained properly while a portable AC will last around eight years, which is worth factoring in. It’s also worth keeping in mind ways that you can cool your home for free. Our five must-dos in a heatwave are:
-
Keeping all windows closed, blinds and curtains drawn during the day and then opening up at night to let hot air out of your home.
-
Using a fan to blow hot air out of the window in the evening when temperatures reduce.
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When the temperature drops, create a cross-breeze by opening windows on opposite sides of your home to help air circulate.
-
Keep internal doors open to allow air to circulate within your home.
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Sleep downstairs or in a cooler room if possible.
And with searches for portable air-conditioning units soaring and many selling out online from high street retailers, shoppers need to be aware of scams.
Before buying online make sure you’ve checked if the website is legit and read reviews if it’s not a well-known brand.
You might be tempted to buy one off a marketplace website or social media, stop before you buy and ask yourself whether the price is too good to be true.
If you’re buying online, make sure you use a credit card where you get Section 75 protection for a refund if you spend over £100 or a debit card where you can ask for a chargeback.”
Case study: I paid £2k to instal aircon and it was worth every penny
Fashion buyer Brittany Green, 38, from East London paid £2,000 to get aircon installed in her studio flat in June. She lives there with her eight-year-old Cavachon, Piper.
She said: “It’s worth every penny to not be sweating and getting hot and bothered at night. Everyone knows it’s unbearable sleeping in a heatwave and I’m so glad I decided to get air con installed.
Piper, my dog, is delighted too - she was boiling during last summer.”
Interviews and pictures available on request.
-ENDS-
Running costs are based on nine hours of overnight use and calculated as follows:
Pedestal fan (50W average)
- 0.05kW × 9 hours = 0.45kWh
- 0.45 × 26.11p = 11.75p per day (rounded to 12p)
Portable air conditioning unit (1kW average)
- 1kW × 9 hours = 9kWh
- 9 × 26.11p = £2.35 per day
Installed air conditioning (continuous full power, 1.5kW average)
- 1.5kW × 9 hours = 13.5kWh
- 13.5 × 26.11p = £3.52 per day (rounded to £3.50)
Installed air conditioning (realistic overnight usage) Based on one hour of cooling at full power, followed by eight hours cycling at 40% output:
- Hour 1: 1.5kW × 1 hour = 1.5kWh
- Next 8 hours: 0.6kW × 8 hours = 4.8kWh
- Total = 6.3kWh
- 6.3 × 26.11p = £1.64 per session
The estimate of 59 hot days per year is based on analysis of Met Office historic temperature data using Heathrow and recording the number of days in 2025 when temperatures were above 25°C.
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