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.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.How can I avoid using air conditioning?Fan favourite: moving air across your skin helps sweat evaporate, making hot days more bearable. Photograph: Westend61/GettyFansThere 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.Air coolersEvaporative 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.Importantly, evaporative coolers (sometimes known as swamp coolers) humidify your air, so aren’t a good option if you have damp and mould problems. They’re designed to be used with doors open and fresh air circulating. Many of the ones I recommend are now out of stock, but my favourite portable option, the Morphy Richards Flexi Freeze, was available at the time of writing.Keeping cool without electricityThere are natural ways to cool your home, too. The problem is that most houses in the UK have been designed to retain heat, not cope with prolonged hot weather. In countries where super-hot summers are the norm, homes are often built with high-thermal-mass walls, which warm up and cool down slowly, and external shutters that block the sun from entering through windows.We’ve written in depth about alternative ways to keep your home cool this summer. Closing and covering windows can keep out hot air and block solar heat by day – then opening them in the evening lets cooler air into your home, flushing out not just warm air but also the heat stored in your walls.If your home has windows on opposite sides, open both in the evening so cool air can blow through. If you live on more than one level, open windows upstairs and downstairs in the evening. Warm air will rise out of the top windows and will be replaced by cooler air that’s drawn in at the lower level.The case for air conditioningShutter speed: blocking out the sun by day can help keep indoor temperatures down before you turn to aircon. Photograph: John Keeble/GettyThere are valid reasons to own air conditioning, even during a climate crisis. Older people, young children and those with health conditions are more vulnerable to extreme heat, and some homes are simply much harder to keep cool.Like any appliance, an air conditioner has two main sources of carbon emissions: the CO2 generated from manufacturing and disposing of it (known as “embodied carbon” ) and the CO2 generated to power it over its lifetime.To reduce its overall impact, buy a unit that’s built to last, from a trusted brand with a long warranty, rather than the cheapest model you can find. A longer-lasting unit spreads its embodied carbon over many more years. Buying secondhand also reduces the impact, extending the life of an existing unit.But the biggest difference you can make is how you power your air conditioning. If you’re on a 100% renewable electricity tariff, then running it shouldn’t require burning fossil fuels (again, it pays to do your research here). Better still, if you have solar panels and a home battery, you can run aircon using electricity you’ve generated yourself. It’s a significant investment, but one that’s becoming increasingly attractive as fuel prices rise and solar panels and batteries get cheaper.Be aware that if you’re on a standard electricity tariff, the mix of fuels used to power your home will depend on the time of day. Around the middle of the day, electricity is typically supplied by a higher share of renewables. When demand peaks, typically in the early evening, gas-fired power plants are more likely to be brought online to meet it.So, if you can, run your aircon outside these evening peak hours. Use shutters, curtains, open windows and other natural cooling methods first, then use air conditioning for a short time before bed to take the edge off.I’ve tested portable air conditioners here, but for a full rundown on the types available, see the “What you need to know” section at the end of this article.Why you should trust meI’m a veteran, award-winning consumer tech journalist with decades of experience testing gadgets. I’m also a menopausal woman in her 50s, who honestly can’t recall the last time she felt cold – which may explain the appeal of wild swimming at this age. Oh, and I have a degree in engineering. Between the three, I’m well qualified to put these portable air conditioners through their paces, both from a scientific and personal perspective.How I testedTesting conditions: most units were put to work in the same room, with the exhaust hose vented through a casement window. Photograph: Caramel Quin/The GuardianUnsurprisingly, air-conditioning units have been hard to come by this summer, with many sold out, and review samples also in short supply. I focused on units that are going to be restocked and tested six, with details of stock levels and replenishment dates included, where available.Where possible, I tested units in the same 14 sq metre room with average ceiling height, and with doors and double-glazed windows closed, so it was the warmest room in the house. I opened a casement window for the hose.The only exception was the Midea PortaSplit. Its unusual design pairs an indoor unit with a rather heavy outdoor unit that remains permanently connected by refrigerant lines, so you can’t separate the two. As I couldn’t lift the outdoor unit through a window, I tested it in a larger 37 sq metre room with a sliding door – which was the only suitable space available.To test performance, I measured each unit’s power consumption at maximum draw with a plug-in energy meter, although since air conditioners cycle on and off, they don’t use that level of power all the time. The highest settings’ noise levels were recorded using a sound meter app from one metre away, and I measured each unit’s size.I also monitored room temperature with a thermometer placed on the opposite side of the room. This measured how much each unit cooled the whole room, rather than the cold air coming from the vent.Finally, I judged each air conditioner on how effective the cooling felt, how annoying I found the noise and how easy the controls were to use. I also considered the design, how easily each unit could be stored over winter and, of course, its price. Note that all models come with remote controls and on castors.All of the aircon units that weren’t collected by the manufacturers after testing were donated to charity. Some went to Furnishing Futures, a charity that creates fully furnished homes for women and children who have survived domestic abuse. And some went to Lowri House in Hackney, London, which provides safe, short-term accommodation for homeless patients leaving hospital, with support from the homeless and inclusion health charity Pathway.skip past newsletter promotionafter newsletter promotionThe best portable air conditioning units in 2026Cool contenders: six portable aircon units were assessed for cooling, noise and energy use. Photograph: Caramel Quin/The GuardianBest portable air conditioner overall: Meaco MC10000MeacoMC10000£459.99What we loveSuperb coolingWhat we don’t loveRemote is basic and there’s no app Photograph: Caramel Quin/The Guardian£459.99 at Aircon CentreCurrently out of stock; stock due 27 November This 10,000 BTU air conditioner is from the popular MeacoCool (MC) range. There are also Pro and CH models that offer a companion app and heating.It’s A-rated for energy efficiency and designed for a medium room. The controls and display sit on the top at an angle, so you can see them from a distance. This is welcome, as the remote control is pretty basic, and there’s no companion app.It uses R290 (propane) refrigerant, which has a low global warming potential of 3.3 (for more information on this, see the “What you need to know” section at the end of the page).Why we love itOn test, this was simply the best and fastest at cooling. It brought the temperature down by 3C in 15 minutes and 6C in two hours.The design is simple. For example, you have to manually open the louvres (the angled grilles on the front) and point them where you want the cold air directed. By directing them downwards, it created a cooling breeze on the floor and on my legs, which I found made everything feel cool.It also has a fan and dehumidifier. The sleep mode dimmed the display but didn’t immediately make it quieter, instead gradually increasing the target temperature by a couple of degrees throughout the night.It’s a shame that … the remote doesn’t have a display.Dimensions: 32 x 32 x 74cm (WDH)Weight: 26kgBTU: 10,000Room size: medium (up to 28m²)Warranty: three yearsMeasured power use on top setting: 890W Peak noise level on test: 60dBMeacoMC10000£459.99What we loveSuperb coolingWhat we don’t loveRemote is basic and there’s no appBest portable aircon unit for large rooms: Dimplex Eco IQDimplexEco IQ£599.99What we loveGood cooling, app and voice controlWhat we don’t loveLoud and the remote is basicCaramel Quin testing air conditioners: Dimplex Photograph: Caramel Quin/The Guardian£599.99 at DimplexCurrently out of stockThe Dimplex Eco IQ has a really handy app featuring controls such as a 24-hour timer. It uses R290 (propane) refrigerant, which has a low global warming potential of 3.3.Why we love itThe unit looks classy, and is pretty compact considering it’s powerful enough for a large room. It offers 12,000 BTU, plus wifi and app control. This means you can control it from your Amazon Alexa or Google Assistant smart speaker if you want to control your aircon by voice.The cooling is impressive. It cooled the room by 1.5C in 15 minutes and 5C in two hours.I found the Dimplex a bit loud, though. It may measure the same number of decibels as others, but it has a fairly deep hum and a slight rattle, like the noise you hear from a fridge. This makes sense because, like a fridge, it uses a compressor and a refrigerant. The noise measured 60dB at its loudest (similar to a conversation – so you’ll definitely hear it, but you can learn to ignore it), and this went down to 55dB on sleep mode. However, I found the noise worth it for the cooling on a hot day.It’s a shame that … it’s loud. The remote control is also basic, to the point of looking a little cheap. It lacks a display, which is a shame because the unit’s display and controls are on top and so can’t be seen from across the room. You can always use the app, though.Dimensions: 29 x 34 x 70cm (WDH) Weight: 23.8kgBTU: 12,000Room size: large (up to 35m²)Warranty: one year, extended to two if registered within 28 daysMeasured power use on top setting: 1,400WPeak noise level on test: 60dBDimplexEco IQ£599.99What we loveGood cooling, app and voice controlWhat we don’t loveLoud and the remote is basicBest split portable air conditioner: Midea PortaSplitMideaPortaSplit£1,099.99What we loveQuiet; energy efficient; great for suitable spacesWhat we don’t loveBulky; positioning limited because of the pipes Photograph: Caramel Quin/The Guardian£1,099.99 at JoyBuyCurrently out of stockAnd now for something completely different. This “portable split” air conditioner has an indoor and outdoor unit, connected with refrigerant pipes. The pipes are 2.5 metres long and have a 6 x 2.7cm cross-section, instead of the usual 15cm diameter air hose.The units can’t be detached from each other because the pipes are full of refrigerant (R32, global warming potential 675), so it’s suitable only if you’re able to put the outdoor unit outside and close the door to leave a 2.7cm gap. Alternatively, you can mount the outdoor unit outside permanently if you’re able to accommodate space for the pipes. I found it easiest to bring it back inside when not in use: it stores neatly on top of the indoor unit. It also comes with a kit for sealing out hot air and a window lock, consisting of two fittings to stick on to the frame with Velcro to connect them, which keeps your window gap narrow.It’s large and heavy: you wouldn’t carry it up and down stairs, although it wheels around OK. If you’d struggle to get the 32.5kg indoor unit and 9.9kg outdoor unit into place, you may find JoyBuy’s £35 installation service good value; they’ll unpack it and bring it to the right room in your home. They’ll even mount it on the no-drill-required brackets if you have a suitable window.Why we love itIt’s much quieter than a “monobloc” one-piece portable aircon unit and could be a permanent fix for renters in modern flats. If you can bring it up to your flat in a lift and have a balcony on which to put the outdoor unit, you’re winning. And it offers year-round service: it’s an efficient A++-rated air conditioner and also an A+-rated heater.And despite its bulk, it’s good-looking. Controls are intuitive, and there are three displays: one on top with the controls, one on the front showing the target temperature, and one on the remote control. You can also control it via the app and add Amazon Alexa or Google Assistant voice control.It cooled the room during testing, and the dog approved of its cooling prowess, but comparing figures would be like comparing apples and oranges: the room I tested it in was considerably larger.If the Midea suits your home – a back door or a balcony really – it’s a good option.It’s a shame that … it’s only suitable for homes that can accommodate its pipes.Dimensions: indoor unit, 52 x 34 x 65cm (WDH); outdoor unit, 50 x 26 x 44cm (WDH)