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It’s hard to say whether it’s good or bad news at this point, but Britain is in for yet another heatwave — the fifth of this summer.

The Met Office has issued new heat health alerts, with highs of 36°C expected in parts of East Anglia and south-east England by Thursday.

And as the nation braces themselves, there’s one home fitting that’ll make you the envy of the street: portable air conditioning.

The cooling units first flew off the shelves when the country saw record June temperatures of 37.3°C, with near-apocalyptic queues when Lidl and Aldi both launched ranges.

Most units at the discount supermarkets are still sold out, but the savvy shoppers here at Metro have scoured the internet to find the best options currently available — some with speedy delivery or in-store collection.

Figuring out what to buy isn’t simple however — there’s a lot of choice and we all have different needs. So, we’re here to help you navigate this new world of exhaust hoses and BTU calculators, with our easy guide to buying a portable aircon unit and if they are actually worth having.

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All portable air conditioning units listed below were in stock at the time of publishing on 11th August — good luck!

How do air conditioners work?

Air conditioners remove the heat from your room, leaving the indoor air cooler. But, there are two types of portable air conditioners. A ‘single hose’ and a ‘dual-hose’.

Katie Lillywhite, air treatment expert at AO.com tells Metro: ‘Single hose air conditioners have one hose to vent hot air from the appliance. This works by drawing air from your room, cooling it through its system then venting this out.

‘[They] lack a bit of power to cool particularly hot rooms.

‘Dual hose air conditions have a lot more power – one hose to pull in outdoor air and the other to vent this back out.’

@metrouk

Is aircon becoming unavoidable in the UK? We’ve got a heatwave bringing temperatures of up to 30C, and 40-degree summers could soon be our new normal… Climate advisers have started warning that air conditioning will be needed in parts of the UK, and cooling measures will have to be ‘rolled out at scale.’ 🎥 @zofia_louise #aircon #heatwave #globalwarming #climatechange

♬ original sound – Metro – Metro

How do I set up my portable air conditioner?

Portable aircon units look a bit bonkers, as you need to put the exhaust hose outside via a vent or in most cases, a window.

Jamie Hillard, of Heatable.co.uk, tells Metro his tips for installation.

‘Installation is key and the exhaust hose must be sealed properly at the window to prevent warm air from coming back in. The exhaust hose needs the shortest, straightest route possible to the outside. Long, kinked, or poorly positioned hoses reduce performance because the hot exhaust air can radiate heat back into the room.

‘The window opening also needs to be sealed properly. A proper window sealing kit or rigid panel makes a noticeable difference.’

Most units come with a kit, or you can by window sealing kits for portable air conditioners online, with heatershop selling them for only £19.98. You can also find them on Amazon.

But one Metro reader has resorted to ‘sealing’ the gap with a giant bit of taped plastic sheeting, noting that the fitting kits are ‘quite fiddly’. She says the result is imperfect, but the room still gets significantly cooler.

It’s not a look for Interior Design Masters though…

What unit do I need?

Figuring out what you need for your house depends on various factors such as the room size and height, the size and condition of the windows, the insulation for the house, the direction the room faces and even the type of room. For example, a conservatory or loft will need more strength than a bedroom of similar size.

‘A really common mistake is buying an undersized unit and if the unit is too small, it will run almost continuously, using more electricity but still struggling to bring the room temperature down,’ says Jamie.

To find the best option, you need to use a BTU calculator, which stands for ‘British Thermal Unit’ and this measures how much energy something has.

How much will it cost?

‘Running costs depend on the size of the space, insulation, glazing, solar gain, tariff, and how aggressively the system is used,’ Jamie says.

‘The biggest mistake is setting the target temperature too low. Trying to cool a room to 18°C during a hot spell will use far more electricity than maintaining it at around 22–24°C.

‘For portable AC units, many models are in the 1–1.5kW electrical input range when running.’

Doing the maths on that, using an electricity calculator, it is on average £0.06 per 10 minutes, which per hour is 36p or £8.64 per day, though it is unlikely you would run it 24 hours.

‘Homeowners can reduce running costs by closing blinds on south- and west-facing windows, keeping windows shut during the hottest part of the day, and cooling rooms before they become overheated,’ Jamie recommends.

What brand should I get?

What about the impact on the environment?

While portable air conditioning units can be done on the cheap, they aren’t always eco-friendly. Like most tech, there are eco mode options and energy ratings. Plus, if you have solar panels, you can power your units that way. But even if you cannot, Andrew Sissons, the sustainable future director at the charity Nesta, says people shouldn’t feel guilty for using them, acknowlidng they are a ‘last resort’ for many people.

Additionally, Nicole Miranda, a sustainable cooling researcher and carbon reduction manager for the University of Oxford, notes that they can be vital in keeping vulnerable people safe in dangerous weather.

Though Earth.org do report that air conditioners are worsening global warming, they advise setting them to 26°C instead 24°C, which consumes around 30% less energy. They reccomend regular cleaning and replacing of the filter too so it does not use more energy, and opting for models with a high Seasonal Energy Efficiency Ratio (SEER).

So, are they worth it?

Though the upfront cost will be a few hundred pounds, and you could be spending approximately up to £8 a day, hot weather can cause dehydration, overheating and heatstroke.

According to the head of the World Health Organization (WHO), the heatwave in Europe has already been linked to 1,300 deaths.

People over 65, babies and children under 5, and those with pre-existing health conditions are espiecally vulnerable.

Steve Charnock, Audience Writer for Metro, who recently bought a 9,000BTU Ariston unit from B&Q for £225, says he had his on ‘constantly’ all of last week, and claims it ‘pretty much saved my life’.

Though, he notes ‘I’ll find out next month if it’s also pretty much bankrupted me’ refencing the daily running costs.

But in comparison, according to Checkatrade, an average, a 12000 BTU wall-mounted unit costs around £750, plus £1,150 for installation and air conditioning engineers typically charge around £280 – £720 per day.

So a portable air conditioning unit is far cheaper and keeps you cool, sane and most importantly safe.

This article was originally published on July 6 2026, and has since been updated.

Do you have a story you’d like to share? Get in touch by emailing MetroLifestyleTeam@metro.co.uk

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