Don't buy air conditioning until you've read this

Families across the country are having their annual discussion/argument about whether it's time to invest in air con.

Less than 5% of UK homes have it, but that number is set to grow as sweltering conditions - like the ones we've seen this week - become more common.

So for those taking the plunge, what should you look out for when making a purchase? We spoke to experts to find out...

Is it actually necessary in the UK?

Ahmed Karim, a lecturer in refrigeration and air conditioning at the College of North West London, says it hasn't traditionally been considered essential due to the relatively mild climate in the UK.

But that's changing - Britons have experienced frequent heatwaves over the past decade and modern homes are "often built to retain heat very efficiently", making it more uncomfortable in summer.

"Most modern systems are now also heat pumps, so they provide heating as well as cooling, which is considerably cheaper to run than conventional boiler systems," Karim adds.

"That means they can be used throughout the year, not just during the summer."

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So, while Karim says air conditioning may only be used for cooling between 10-40 days a year, the system can be maximised during the colder months.

How much do they cost?

Will Jones, home expert at Currys, says the market has evolved and air conditioning is far more accessible than it once was.

"There's a wide range available. Most models differ by the size of room they can cool, energy efficiency rating and added features such as heating, dehumidifying or smart controls," he adds.

Jones says prices can start at around £299 for portable models, while professionally installed split systems can exceed £1,000.

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What are the different types?

• Portable air conditioners - standalone units that can be moved around and vent through a window;
• Wall-mounted split systems - the most common permanent installation, with an indoor unit and an outdoor condenser;
• Multi-split systems - one outdoor unit serving several indoor units across different rooms;
• Ducted systems - more common in larger homes or commercial buildings.

Most UK households elect for either portable units or wall-mounted split systems, according to Karim.

How much does it cost to run?

Modern air conditioning systems are "very energy efficient" and can roughly cost 15-40p per hour, according to Karim.

Depending on the size of the room, those wall-mounted units might use roughly 500-3,500 watts.

Natalie Hitchins, head of home products and services at Which?, says tests of the average portable air conditioner found that it uses 22p per hour on its highest setting.

"That's about as much energy as a typical fridge freezer uses in one day," she adds.

"Fixed units are more efficient and can be quieter, but they are pricier and need to be installed by a professional."

Karim adds: "If the system is used for heating as well, the running costs can sometimes be lower than traditional electric heating."

Do portable ones work?

While they do work, portable air conditioners are "less efficient and less powerful" than fixed systems.

Karim says they can be effective for cooling a single room, including bedrooms and small living areas. However, the systems struggle in large or poorly insulated spaces.

They work best in small flats that don't have permission to install fixed evaporator and condensing units.

What should buyers look out for?

Jamie Hillard, a registered engineer at Heatable.co.uk, says the most important thing to look out for is the unit's "cooling capacity" - usually shown in BTU (British thermal unit) or kW (kilowatt).

Customers should also be aware of the room size the unit is rated for.

"A really common mistake is buying an undersized unit," Hillard warns.

"If the unit is too small, it will run almost continuously, using more electricity, but still struggling to bring the temperature down."

He says small UK bedrooms generally need around 2 to 2.5kW of cooling, while larger living spaces require 3.5kW, depending on window glazing, what sort of insulation the home has, which direction the room faces and how the room is used.

"For example, if you get a lot of heat gain from multiple people, multiple appliances running, among other ways," Hillard adds.

Which is better, portable or wall-mounted?

Wall-mounted systems are usually "far better" when it comes to efficiency, performance and noise levels.

Karim says portable units are a better option as a temporary or budget solution, whereas wall-mounted systems "provide more consistent cooling and offer heating".

Are air-con units noisy?

Indoor units on wall-mounted systems can be as quiet as 20-30 decibels, similar to a whisper or a quiet library.

But outdoor air conditioning units do make noise. Karim says this is comparable to a small fan, roughly hitting the 50-65 decibel mark.

"Portable units tend to be noticeably louder because the compressor is inside the room," he adds.

Those outdoor units are louder than your usual pedestal fan, one of the popular choices among Britons, ranging from 31 decibels on low power to 45.9 decibels at full speed, according to expert reviews.

Practically, what do portable ones need?

The portable units require a vent hose that is connected to a window, "so the hot air can be expelled", meaning they can sometimes be difficult.

"They can also be fairly heavy, so while they are technically portable, moving them between floors isn't always convenient," Karim says.

"Some models also require emptying a water tank, although many newer ones evaporate the moisture automatically."

Choosing the right portable unit

When it comes to portable air conditioning, there are a few key areas to be aware of, according to Hillard.

• The hose issue: Single-hose units create a slight negative pressure, which can pull warm air from other rooms, making them less efficient (bringing us back to it running for longer and working harder to keep the temperature down). Dual-hose units are more efficient. This is a real issue with many portable air conditioning units sold in the UK.
• Single-hose units: They use air from the room to eject heat outside. Because it is pushing air out through the exhaust hose, replacement air has to come from somewhere and that's usually under doors, through trickle vents, chimneys, loft hatches, or gaps around windows. In practice, warm air is being pulled back into the property while the unit is trying to cool it.
• Dual-hose systems: They are more efficient because they separate the condenser air path from the cooled room air. One hose draws outdoor air in, the other ejects hot air back out. That reduces the negative-pressure effect and generally improves cooling performance, particularly in hotter weather. Single-hose units can still work, but buyers should see them as a compromise: convenient and relatively cheap, but less efficient than a properly installed split system or a well-designed dual-hose portable unit.

Hillard says good installation is "key" and can be the difference between a unit that works and one that doesn't cool as well as it should.

"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," he adds.

"The window opening also needs to be sealed properly. If the hose is simply hanging out of an open window, warm air will come straight back in, particularly in upstairs rooms where solar gain is already high."

Maintenance is also crucial. Hillard says "filters need to be cleaned regularly" as restricted airflow reduces cooling output and can ultimately lead to higher electricity use.

Best models to buy

Okay, so now we've covered everything you need to know about buying an air conditioner like a pro, the biggest question is - what are the best products available?

According to Ideal Home, the MeacoCool MC Series portable air conditioner is the best overall product. It's "affordable, lightweight and compact", as well as energy-efficient and easy to use.

The best affordable option is the VonHaus High-Performance air conditioner, available for less than £300. Ideal Home's tester said it was easy to operate and quickly cooled a bedroom to a comfortable temperature.

The best available option for power is the AEG Comfort 6000 portable air conditioner, which "looks good, is easy to use, relatively quiet in comparison to most", and has WiFi connectivity. It can also cool down a room very quickly, but it can lead to slightly higher running costs.

Could it add value to a home?

With the increasing expectation for modern homes, apartments and higher-end properties to have climate control, air conditioning can absolutely add value to your home.

"While it might not dramatically increase property value on its own, it can definitely make a property more attractive to buyers, especially as UK summers become warmer," university lecturer Karim says.

Ben Gallizzi, energy expert at Uswitch.com, agrees, saying that the "popularity of air con is increasing" across the UK and if a home has a good quality system, it can make the property "more attractive to buyers in the future".

(c) Sky News 2026: Don't buy air conditioning until you've read this