Environmentalists say you shouldn’t have air-con. This is why they’re wrong

As the UK swelters through the longest heatwave of the year, you might be thinking of investing in some form of air conditioning. Not so fast. Air-con only worsens the problem of the warming world it is supposed to fix, say some environmentalists. So how well do their arguments stand up to scrutiny? Contrary to what climate change deniers might say, there are no longer any meaningful doubts about fossil-fuel-driven global warming. Only this week, the latest Met Office report found that average UK temperatures have risen by 1.3°C since the 1960s, and the hottest summer temperature has risen by up to 4.5°C. Shorts As a result, many of us are sleeping badly at night and getting hot and bothered by day. Overheating can affect health too, and heatwaves like the present one cause a noticeable rise in the number of deaths from conditions such as heart disease. The question is how the UK copes with these warmer summers. Unlike the US, only 4 per cent of homes in England have any form of air-con, whether the cheaper portable units that dangle hoses out of windows, or the more powerful fixed wall units that cost several thousand pounds for multiple rooms. Air-con faces some official resistance in Britain. Government advice, such as from the UK Health Security Agency, is we should instead ramp up “passive” cooling strategies, like closing curtains by day, and using shutters and awnings, like in Mediterranean countries. In many areas, building regulations mean new homes rarely have pre-installed cooling systems. Developers are supposed to prioritise other measures instead, like giving houses shutters and smaller windows, using air-con only as a last resort, because of its environmental impact. At a recent press conference on heatwaves and climate change held by the Science Media Centre, Professor Lucelia Rodrigues, a sustainability expert at the University of Nottingham, said: “We need to create homes that enable natural ventilation, reducing unwanted heat gains. The worst-case scenario would be for people to be installing air conditioning in their homes and schools.” One of the issues is that air-con literally expels heat from a home to the outside. “Imagine all the flats in big urban centres have air conditioning – it’s going to make cities so much hotter,” said Dr Anastasia Mylona, technical director at the Chartered Institution of Building Services Engineers. But in practice, that effect is negligible. For instance, one US study estimated that even during a severe heatwave in Phoenix, Arizona, outside air temperatures would be raised by the extreme air-con use by less than 0.5°C in the daytime. Worsening the warming A more serious concern is that in the long term, the electricity used by air-con is only going to worsen global warming. “Because two-thirds of the world’s electricity is still produced by fossil fuels, cooling’s soaring electricity demand is increasing greenhouse gas emissions,” said Professor Rodrigues. That is certainly true, but on the other hand, residential air-con is responsible for a tiny fraction of the UK’s overall power use, currently about 0.1 per cent. “There’s much more energy used for heating and industry and transport,” said Professor Jan Rosenow, a climate policy scientist at the University of Oxford. And while air-con use is predicted to rise, so will the country’s adoption of renewable energy sources, like solar and wind power. “Yes, there’s increased energy demands, but increasingly that energy will be low carbon or zero carbon,” said Professor Rosenow. Power blackouts The power use is not just about our carbon footprint, though. There is also concern that during heatwaves, high demand for air-con could exceed the power grid’s capabilities. This problem has led to localised blackouts in Australia during hot summers and is what recently prompted New York Mayor Zohran Mamdani to ask residents to set their air-con to no lower than 25.5°C, to ease strain on the grid. But it shouldn’t be a problem in the UK, where home air-con use is so low. Even as uptake rises, heating systems in winter use much more power than air-con in summer, so it is unlikely to be too much for the UK grid. “If the grid is built large enough to cope with all the heat pumps we’re going to have to install, it will also be able to accommodate air conditioning,” said Professor Rosenow. The switch to solar power is especially helpful as air-con use rises the most when the sun’s rays are at their strongest. The final argument against air-con is that it worsens health inequalities, as renters and less well-off homeowners cannot install the most effective, fixed systems. “People that are left without air conditioning are going to be much worse off than people that can afford air conditioning,” said Dr Mylona. However, it is worth pointing out that the cost of window shutters or awnings can also run into thousands of pounds. Greening air-con Regardless of any antipathy to air-con, homeowners are increasingly installing it, especially in the warmer parts of the UK, where people have been sweltering in the current prolonged heatwave. “We need to have a safe space to work, a safe space to live,” said Dr Henrique Lagoeiro, a heating and cooling researcher at London South Bank University. That makes it all the more important that consumers are guided to the most energy-efficient systems that use the least climate-harming chemicals. They should also be advised they can continue to use other cooling measures, like shading and fans, alongside their air-con to cut power bills. The greenest option of all would be if more homes could use combined heating and cooling systems called air-to-air heat pumps. This is the most climate-friendly option as it shifts people over to low-carbon heating at the same time. In a promising move, homeowners in England and Wales can now get a £2,500 Government grant towards the cost of these systems, but this only began in April. “Air-con is not something to fear,” said Professor Graeme Maidment, a heating and cooling researcher at London South Bank University. “It’s something that is going to happen, most probably. But when it happens, we need to make sure that we do it in the best way possible.”