3 things to consider before buying an air conditioner

I think everyone (especially in the UK and Europe) should be investing now, but there are some checks and measurements to take care of before you buy

Heatwaves are one of the biggest European stories of 2026 so far. With a new heatwave seemingly arriving at least monthly, it’s definitely time to invest in air conditioning.

Sure, you could get a wall-mounted unit with pipes that lead outside, but this option is expensive, requires professional installation and means it’s fixed in the room where the unit is (assuming you get one).

For most people, I’d recommend a portable air conditioner like the Dreo model I’ve been testing. It really is a brilliant piece of kit and a proper life- or sleep-saver once the mercury hits obscene levels.

No doubt you’ve experienced air conditioning in a car, hotel room or similar, so you don’t need me to explain what it does or how it works. And while I think everyone should be investing in one now, based on my testing, there are three things you should consider before buying.

The cost

While an air conditioning unit might seem expensive considering you can get a little fan in the supermarket for likely less than £10, it’s not really a fair comparison. A fan can’t actually lower the air temperature – it can only make you more comfortable in the heat. An air conditioner will actually cool the air around you. Plus, it’s packed with clever tech.

For example, the Dreo Portable Air Conditioner 318S I’ve been using has three different modes, including fan and dehumidifier, so it’s more than just aircon. Plus, it’s Wi-Fi-enabled, so I can control it from my phone as well as get info in the app, such as when the filter needs cleaning.

This model is just £399, which I think is very good value. It’s probably cheaper than the smartphone you’re reading this on and will last a lot longer too. Plus, it’s still cheaper than some of the high-end fans you might be considering from the likes of Dyson or Philips.

The problem right now is finding them in stock. The 318S is sold out on the official store and Amazon, but Amazon does have the more advanced 516S for £599 at the time of writing. We’ve also tested the Midea Comfee 9000 BTU air conditioner, which is another effective and reasonably priced option – again, if you can find it in stock.

If you can’t find an air conditioner at all at the moment, an air cooler (such as the Princess Smart Air Cooler, which we’ve also reviewed) can help a little, although in a closed room, it can make the air muggy and humid.

When you buy a portable air conditioner, look out for the BTU measurement. BTU stands for British Thermal Unit, the standard measurement of heating or cooling capacity. The BTU number shows the amount of heat an AC unit can remove from a room every hour. The higher the BTU measurement, the larger the room it can cool. 5-7000 BTU will cool a small room, like a typical bedroom.

The Dreo I’m testing is 7500 BTU and I’ve found that it cools my bedroom noticeably in only 15-20 minutes.

The noise

Cost is one thing, but air conditioning isn’t for everyone, even if it does cool a room in a way that a fan can’t.

When in cooling mode, the compressor is fairly noisy when it’s in use (which is a lot of the time in a heatwave). This, combined with the fan blowing the cold air out, might be enough to disturb your sleep.

People who enjoy white noise while they’re dropping off might find this to be a plus, so it depends on which camp you’re in. The 318S mostly produces a constant sound but can be a little rattly when it’s windy.

If you need absolute quiet to sleep, then getting a fitted air conditioner is the way to go – if you can afford one.

The practicality

A portable air conditioner is great in that you can wheel it around from room to room as and when you need. The units feature wheels, but that’s only a small part of the practicality story here.

Wheeling it around is fine if you have space to do it (these things aren’t typically small) and don’t have to deal with moving between hard floors and rugs often. The wheels on the 318S are small and they struggle with rugs and likely would with thick carpet, too.

However, if you want to move it between floors, carrying it up and down stairs is going to be a massive pain, or not possible at all for some people, considering they typically weigh between 20-25kg.

Then there’s the vent pipe (to get the hot air produced outside) and the window kits you need to make it work with your window. I can’t use a portable air conditioner downstairs in my house because the supplied pipe is simply too short to reach any windows. I’d have to buy a separate longer one, which isn’t as cheap as you might expect.

You need to measure how far the pipe will have to go before buying, as it might be a big disappointment. Also, check that the model you’re buying comes with a window kit that’s compatible with the style of windows in your house (although you might be able to DIY a workaround).

The Dreo comes with a range of different options, which is great, including sash windows, a zipped fabric option for a typical hinged window and even a vent you can put in the wall if you’re willing to drill a big hole in it.

Luckily, thanks to thick curtains in the bedroom where I mainly use the device, I’m able to seal the pipe well enough that only a small amount of air comes into the room from outside.