As hotter summers become the norm, home aircon can feel increasingly tempting. We put six units to the test for cooling power, noise and energy use – and explain what you need to know before buying
How to sleep in a heatwave
Can air conditioning be green?
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Tell people you’re testing air conditioning, and the truth soon comes out: far more people have aircon than you’d ever imagine. It’s a guilty secret, the home improvement equivalent of Botox or weight loss jabs – everyone notices the results, but nobody admits to the method. Most portable aircons are in bedrooms, hidden away from visitors, so they’re easy to keep secret. And while friends with aircon don’t suddenly look younger or slimmer, they do look suspiciously well rested during a heatwave, while you’ve spent the night tossing and turning.
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So if you’re using an aircon unit, why have it in the bedroom? Warm air rises, so upstairs bedrooms can be the hottest by the end of the day, making for restless nights. And if your bedroom is in a loft conversion, it’s even worse: the roof absorbs the sun’s heat all day before radiating it back into the room after dark.
Most UK homes are built to retain heat, not shed it. Cooling an entire home is difficult and expensive, but a single aircon unit can make at least one room – and a good night’s sleep – more achievable.
So, should you get aircon? And if you do, should you feel guilty about it? Yes and no. It depends on how you power it, whether the machine is built to last, and whether you really need it.
We are in a climate crisis. This year’s hot summer hasn’t been a blip. In fact, extreme heat and flooding will worsen in the coming years. We got into this mess by burning fossil fuels, and we continue to do so, so the carbon footprint of your cooling matters. You could be making the problem worse by opting to have air conditioning. Unless you’re on a renewable tariff – or even better, producing itself yourself with solar panels – electricity use accelerates climate breakdown. (If you are looking to move to a renewable tariff, it’s worth researching those that invest most in renewables.)
Before you buy, read the “What you need to know” section at the bottom of this page on the global warming potential (GWP) of refrigerants. These are used in air-conditioning units, as well as fridges, freezers, heat pumps and other appliances that move heat. Some refrigerants have a global warming impact hundreds, or even thousands, of times greater than the same amount of CO2 if they escape into the atmosphere.
We were facing our fifth heatwave of the year at the time of writing, and unsurprisingly, portable air conditioning units had been in high demand. None of the options I’ve recommended is currently in stock, with the first restock due in late November, and many more expected in March 2027. If you want a good-quality, well-recommended unit that’s built to last, bear that in mind. So take your time: these units are big investments built to last, and there’s lots to consider.
There are cheaper (and greener) alternatives to air conditioning, including fans and evaporative air coolers, both of which I’ve tested for the Filter. Fans don’t actually lower a room’s temperature; they simply move air across your skin, helping sweat evaporate and making you feel cooler, like a breeze on a hot day.
If you decide to go with a fan, buy a good one (my favourite, the Lume, is now on preorder for delivery from 31 August). Cheap models are often noisy, with much of that noise being wasted energy. A well-engineered fan is noticeably quieter and more effective.
As you might have already discovered, fans and air coolers often sell out during hot weather, especially the good ones. If you find a model you like on preorder, it’s usually worth reserving it. Sadly, we’re likely to see more heatwaves.
Evaporative air coolers work by drawing warm air through water-soaked pads. As the water evaporates, it absorbs heat, cooling the air by a degree or two, before it’s blown back into the room. The result isn’t the fridge-like chill of an air conditioner, but a gentler cooling effect – like a sea breeze on a hot day. The trade-off is that the fans built into evaporative coolers are often less powerful, so you don’t get the strong blast of air that you get from a standard fan.
