Unless you’ve been living under a rock, you’ll have noticed that UK summers are only getting hotter (maybe it’s cooler under the rock?). This means more people than ever are seriously considering air conditioning.
A worry for some people however, is the concern over the potential for air conditioning to be bad for the environment.
We’ve answered this here, looking also at how you can use air conditioning responsibly, whether different types of AC are better for the environment, and what the health case for air conditioning is.
🔑 Key Points:
Air conditioning does have a carbon cost, but not all AC units are created equal.
Modern wall-mounted AC units are much more efficient than portable models.
Used responsibly, AC can prevent heat-related illnesses and even save lives.
Choosing the right system and using it wisely is better for your wallet and the planet.
Ready to beat the heat and get cool? Find out exactly what size air conditioner you need and get a fixed price in seconds here.
What’s the Environmental Cost of Air Conditioning?
Air conditioning can impact the environment in two ways – through high electricity usage and through the potentially polluting effects of the refrigerant many AC units use.
For the electricity usage, AC units, while generally efficient, do still require a high amount of energy to run. And when the weather is warm, most households run AC units throughout the day (and often through the night if it’s really warm). This is going to mean a big increase in electricity usage in the UK.
In fact, the International Energy Agency (IEA) predicts that AC units will be the biggest contributor to growing energy demand around the world.
All this increased energy usage will inevitably put a strain on the National Grid, which could result in the UK needing to burn more fossil fuels to meet the growing demand.
While renewable energy sources are continuing to make up a greater share of the grid’s energy mix, whether it’d be enough to fully cover the electricity demand from AC units is currently unknown. Simply put, more people using AC will cause higher demand for electricity, which if provided by fossil fuels, will be bad for the environment.
As for the refrigerants AC units use, these have historically been made from chemicals that when emitted into the atmosphere, can be much worse than carbon dioxide. Called HFCs (hydrofluorocarbons) and HCFCs (hydrochlorofluorocarbons), these refrigerants can damage the environments in different ways:
HCFs are a greenhouse gas that can contribute to climate change.
HCFCs can deplete the ozone layer, allowing more harmful ultraviolet (UV) radiation from the sun to break through, which can damage skin, plants, and ecosystems.
However, these days, most modern AC units use R-32 refrigerant, which while still being an HFC, has a much lower Global Warming Potential (GWP) than older versions. It’s also a lot more efficient (meaning less energy is needed) and allows for better cooling in higher temperatures.
There is an even more environmentally friendly option starting to become more popular too – hydrofluoroolefins (HFOs) have exactly zero ozone depletion and a lower GWP than other refrigerants. HFOs are already widespread in many heat pumps and will likely become the default for AC units in the future.
What Makes Wall-Mounted AC Better Than Portable?
Wall-mounted AC units are better for the environment than portable AC units for a few reasons, but the most important one is that they are more energy efficient. Almost all modern wall-mounted units exceed energy ratings of A++, and the most efficient units have Seasonal Energy Efficiency Rations (SEER) ratings of 6 and above.
Portable AC units max out with energy ratings of A, and many can be rated B or lower. So you might be spending less on the upfront cost of a portable unit, but you’ll spend more running it.
Just a quick note on what SEER is a measure of, it’s a way of measuring an AC unit’s cooling efficiency over a season. The higher the SEER score, the more energy efficient it is, the less it costs to run, and the better it is for the environment.
Let’s take a quick look at the energy usage of wall-mounted AC units compared to portable ones:
Wall-mounted AC unit: uses 0.5–0.8 kWh/hour, costing £30.96–£49.41 per year
Portable AC unit: uses 1–1.5 kWh/hour, costing £61.80–£92.40 per year
We calculated this using the current price of electricity, which is currently around 25.73p per kWh according to Ofgem’s summer price cap (valid from 1 July to 30 September 2025).
Another reason wall-mounted AC is better than portable, is the ability to control it with smart thermostats. This technology lets you fine tune the temperature, making sure that cooling only kicks in when necessary which helps avoid wasting energy.
Lastly, there’s inverter technology, which allows wall-mounted units to alter the speed of the compressor (the beating heart of the AC unit that allows it to cool your home in the first place). By altering the speed of the compressor, an AC unit can better modulate temperature, rather than simply being on or off. This in turn saves energy.
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The Hidden Environmental Trade-offs
Opting for or against air conditioning on environmental grounds is not a black and white decision.
For example, you might opt to leave a fan on all day instead, thinking it’s better for the environment than if you’d installed AC.
The reality however, is that you’ll still be spending money on powering your fan for a fraction of the comfort.
A fan does use less electricity than an AC unit, but with AC you can reliably cool a room in far less time.
So you could well be leaving your fan on all day and potentially using more electricity overall.
Another way people think they can keep cooler without AC is by opening the window, but this is a rookie mistake. When it’s hotter outside than inside, opening the window will draw all the warm air into your home.
And if you live in an area with high humidity, opening the window during hot weather events can raise the moisture levels, promoting the growth of mould and mildew.
There’s also the worry of air pollutants entering the home through open windows. It can quite literally be a threat to health to open your window if pollutants are particularly high.
Getting air conditioning means not having to worry about this.
The Health Case for Air Conditioning
Air conditioning can have a positive impact on the health of people with it. For starters, it can play a major role in preventing heat deaths, which are unfortunately becoming more common in the UK. In the heatwaves of 2023, the UK saw 2,295 deaths related to heat exposure.
Extreme heat can also exacerbate health conditions and lead to dehydration and heat strokes. People with cardiovascular issues, the elderly, babies, and those with other chronic health conditions can really struggle in heatwaves too.
Then there’s the mould and mildew we mentioned just above. Air conditioning helps prevent the growth of mould and mildew, which can cause respiratory issues, allergic reactions, and even infections in vulnerable individuals.
Some AC units filter out pollutants as well, so you can purify the air inside your home. If you’re susceptible to hayfever, having an AC unit remove pollen from the atmosphere can be a godsend.
Having air conditioning also means you can leave the window closed and avoid the damaging effects of air pollution. The annual mortality of human-made air pollution in the UK is roughly equivalent to between 28,000 and 36,000 deaths every year, according to government data.
Additionally, air pollution cost the NHS around £1.6 billion between 2017 and 2025. So there’s an argument to be made that not only is air conditioning a direct health benefit, but an economic one too.
How To Use AC Responsibly
If you’re set on getting air conditioning and want to minimise your environmental impact as much as you can, consider these tips:
Get the right size AC. There’s no point getting an oversized AC unit that’s only going to cost you more to run, and use more electricity than is necessary. It’s the same with an undersized unit too, which won’t cool you effectively. Instead, calculate the cooling capacity by measuring the room’s length times the width to find the square footage.
Take that number, multiply it by 25 and you’ll have your room’s BTU (British Thermal Unit). Choose an AC unit that has a comparable BTU.
Choose an efficient AC. When looking to buy an AC unit, keep an eye out for high SEER scores and energy ratings of A++ or higher. More efficient units use less electricity and keep you cooler while costing less.
Adopt healthy AC habits. Try to only cool rooms you’re actively using and if possible, close the doors on rooms you’re cooling to prevent putting extra strain on your AC unit.
Use proper shading and insulation. During the hottest parts of the day, pull down blinds or shutters, or draw curtains to limit temperature increases, and reduce pressure on your AC unit. Proper insulation is important too, as it will actually help keep a room cooler for longer by minimising heat transference.
Set a comfortable temperature. Keep your AC setting at 24–26°C, rather than always turning it as low as possible. You’ll stay comfortably cool and use less electricity as a result.
Get regular maintenance. Make sure you keep your AC unit well maintained so it runs effectively and efficiently. Otherwise, you might face poor cooling and surprisingly high bills. A little TLC goes a long way with AC.
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Next Steps For Your AC Journey:
When planning to install air conditioning for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:
To dive deeper into these topics, head over to our advice section, check out our YouTube channel for informative videos.
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