Does it make sense to get an air conditioner in the UK amid rising temperatures?
As the country gets set for summer and the mercury rises, many of us are dreaming of the icy tang of AC. But is it a waste of money or a smart investment to futureproof your home? Helen Coffey asks the experts
Once upon a time, the very notion of air conditioning was an anomaly to the residents of Great Britain. What a waste of money to have such a monstrosity installed in a building, particularly in one’s home! It would only get used for, what, three, four days out of the year?
However, times have changed, and temperatures have changed with them. In July 2022, the UK experienced its first recorded temperature above 40C; the Met Office warned this week that hitting this level of heat is now 20 times more likely than it was in the 1960s. And as the climate crisis continues to reshape our idea of what constitutes a “normal” summer, things are only going to get hotter.
More than 55 per cent of homes in the UK are already at risk of overheating, according to the UK Green Building Council (UKGBC), whose UK Climate Resilience Roadmap, providing recommendations for the industry and policymakers to “increase resilience to climate hazards”, was launched this week. The housing most prone to overheating is, perhaps counterintuitively, new builds – they’re better insulated and designed to be more energy efficient in winter, but more prone to overheating in summer than existing Victorian houses or older buildings because of poor ventilation.
And it’s not just a matter of discomfort. During the legendary heatwave of summer 2022, England and Wales recorded 3,271 heat-related deaths. The most recent estimate, published in 2021 as part of the UK-wide Climate Change Risk Assessment (CCRA), projected that annual heat-related deaths could more than triple by the 2050s – a leap from 2,000 to 7,000 per year.
Under such circumstances, it’s perhaps little surprise that the use of AC has seen a huge spike over the past decade, rising sevenfold, according to a paper published in Energy Research & Social Science earlier this month. In the last two years alone, air con use has rocketed by 90 per cent, Uswitch.com energy expert Ben Gallizzi told The Telegraph.
And it’s not just offices and commercial buildings contributing to this increase – air con for residential properties is no longer a niche luxury but a burgeoning trend. There has been a “massive jump” in demand for air conditioning in people’s homes, says Mark Cullen, operations director of AC installation company Urban Cooling. “This market is now our key focus,” he adds. “Our main customer base is new build apartments where the ventilation systems just move around hot air and provide no cooling.”
However, before you rush to get your own unit fitted, bear in mind that the experts recommend leaning into passive, low-energy measures first. Not least because, if we all leap to getting AC, we’re contributing to climate change getting worse.
“While we’re still decarbonising the grid, we’re still drawing on those gas-fired power stations and North Sea oil – and so by using air conditioning, we’re still burning fossil fuels and adding to that problem of climate change,” says Alexander Buck, a sustainability specialist at the architecture firm Buckley Gray Yeoman (BGY). “It’s a self-perpetuating circle: we use more air conditioning, then we make the climate warmer, and then we’re going to need more air conditioning.”
It’s the definition of a vicious cycle, and the mass installation of AC could cause other problems too. There’s not only an issue of overheating within buildings, there’s an issue of overheating within the urban environment. “You have two boxes, one’s inside your house, the other’s outside of your house, pumping the hot air out,” says Antonietta Canta, urbanisation and resilience associate at Arup, the global consultancy firm commissioned by the Climate Change Committee (CCC) to assess future risks posed by summertime overheating to UK housing. “So if we were to install air conditioning to make the building cooler, we would make our streets and other areas in the city a lot hotter.”
It exacerbates the existing phenomenon dubbed the urban heat island effect, which sees cities endure temperatures of up to 5C higher than neighbouring rural areas.
There’s also an energy crisis looming, as the country transitions to becoming fully electric, including swapping petrol cars for electric ones and gas boilers for air source heat pumps. “The demand we’re placing on buildings is growing and growing; the demand we’re placing on the national grid is growing and growing,” adds Buck. “It’s been well documented that we’re going to outstrip supply even with the amount of renewables and investment within energy generation. We really have to do everything we can to reduce that demand – reduce the amount of air conditioning, reduce the amount of heating we put into buildings.”
It’s a self-perpetuating circle: we use more air conditioning, then we make the climate warmer, and then we’re going to need more air conditioning
Additionally, says Canta, building designers have to keep in mind human behaviour. “We might say, ‘OK, we’ll install air conditioning, but it will only be used for a week in the summer.’ But when we do install air conditioning, we know that people use it a lot more than is necessary.”
When it comes to reducing the risk of overheating, adaptations will need to be made, says Michael Edwards, building engineering director at Arup, both “in terms of the fabric of the building, but also the way that people use their homes to keep them cool.”
It turns out there’s an education gap when it comes to the second part of this equation; part of the problem is that people don’t always know or implement the basic, common sense and zero-cost measures that help keep temperatures down. Take Georgian and Victorian properties with big sash windows – Buck says he often sees people using them incorrectly, just opening the bottom part. “You need to lower the top bit to let out hot air from the top and raise the bottom bit to allow cool air in,” he explains.
Whatever type of property you live in, though, the techniques for avoiding overheating remain the same. Most people’s natural response to it being hot outside is to fling open all the windows and try to get a breeze in. But “that’s one of the worst things you can do when it’s hot outside, because the air outside is warmer than the air inside”, says Edwards. Instead, you should close all the windows and blinds to keep heat out during the day, and open them again when it’s cooler in the evening and first thing in the morning. Opening windows and doors on either side of your home is important too, enabling cross ventilation. These things might sound small, but they make a massive difference. Canta quotes research that found the “educated user” who deployed their blinds and windows correctly reduced the risk of their property overheating by 30 per cent.
As Buck says, “We need to make sure we’re operating our existing buildings how they were designed to be used.”
In terms of adaptations to buildings themselves, the most effective passive interventions include installing external shading, according to the UKGBC – think awnings, shutters, roller blinds, or even planting a well-placed tree to block sunlight if you have a south-facing property, measures that have long been implemented successfully in Mediterranean and Middle Eastern countries. Reducing window sizes, or using opaque glazing on at least part of the window, plus boosting natural airflow by putting in windows capable of opening wider (particularly an issue with newbuild properties), are also recommended.
If these passive measures fail to cut it as the mercury rises, the UKGBC does list mechanical cooling systems, such as air conditioning, as one of the “active” tactics to consider. However, it warns, “these interventions will result in increased energy use and operational costs”.
Aside from the eco-cost of AC, there’s also the cold, hard cash cost to consider. There’s the price of the unit and installation itself, and then there’s the energy cost, which, at a time when many are still struggling to afford basic necessities and utilities thanks to the cost of living crisis, is no small consideration.
Anyone who is mulling a purchase must decide between opting for cheaper, standalone, portable units and more expensive fitted ones. The former will only cool one room but has the advantage of avoiding installation costs and being more affordable, with units available from around £250 up to £650. The latter are significantly more expensive but more effective – prices range from around £750 to £5,000 for the unit itself, depending on size, power and style (the more concealed or discreet, the higher the price), alongside installation costs of between £1,000 and £2,000, according to Checkatrade.com.
When we do install air conditioning, we know that people use it a lot more than is necessary
Portable air conditioners are also cheaper to operate, typically using 1 kilowatt of power, equating to 27p an hour for electricity. Fitted variants are more powerful, which means they’re more expensive to run; a 2.7 kilowatt model will set you back 73p an hour.
To compare, the most powerful fans on the market retail at a maximum of £270 and their running costs are far lower. The Dyson Cool AM07 tower fan, for example, uses 56 watts of power, totalling just 2p per hour.
There are instances in which getting aircon in your home might make sense; if you’re lucky enough to have solar panels on your roof, or you live in a rural location and have access to ground source heat, you can offset the extra energy and carbon, advises Buck. “I really would advocate that if you are going to try and put in some sort of air conditioning into your property, that you consider it in tandem with what offset you can do. What, in terms of renewable energies, is providing you with the greenest possible electricity?” he says. Installing an air source heat pump would likely be preferable, too, as they can both heat and cool.
At the end of the day, the experts emphasise that it’s not a case of “never” when it comes to air conditioning – there’s a strong case for it in hospitals and care homes, plus buildings that cater for vulnerable people. But it should be a last resort for most of us.
“Our advice would be to absolutely avoid it as far as possible, because that would be a negative outcome if everyone started getting it,” Canta warns. “For the country, for the planet – it would be a very dangerous thing to do.”
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