Europe is getting hotter, and the old continental habit of pretending air conditioning is an American personality defect is starting to fail. The International Energy Agency says only about 20 percent of European homes have air conditioning, compared with roughly 90 percent in the US. In the UK, researchers put household adoption at about 4 percent.
That gap is becoming harder to defend during heat waves. At the end of June, temperatures in parts of Europe climbed above 40 degrees Celsius, and shoppers in France rushed stores for fans and portable air conditioners. The IEA projects that two-thirds of households worldwide could own an air conditioner by 2050.
The politics are already ugly. Marine Le Pen has promised to expand air conditioning across France if her party gains power. British Conservatives have said they would reverse net-zero rules that limit air-conditioner installation in new homes. Critics on the left argue that wider AC deployment risks helping wealthier households first while pushing Europe toward the energy-heavy cooling patterns already seen in the US and Asia.
The technical problem is less tweetable: cooling saves people, and cooling also heats the planet. A research group estimated that air conditioning prevented nearly 200,000 premature deaths among people over 65 in 2019. It can also help people sleep, work and learn during extreme heat. At the same time, air conditioning accounts for about 3 percent of global greenhouse gas emissions, slightly more than aviation, according to Our World in Data.
Fabian Voswinkel, an energy-efficiency policy analyst at the IEA, said cooling is expected to become one of the largest sources of electricity demand growth, alongside data centers. The IEA says electricity demand for space cooling could more than triple by 2050.
The refrigerant problem
Conventional air conditioners move heat by repeatedly evaporating and condensing refrigerant. The physics works. The chemistry is the problem. Fluorinated gases can have a warming effect thousands of times stronger than carbon dioxide when they leak. The European Union adopted rules in 2024 to phase down those gases. Voswinkel said air conditioners and heat pumps using them will become unsellable in Europe in the next few years.
The replacements are awkward too. Propane can burn. Ammonia is toxic. That has pushed researchers toward solid-state cooling, which uses materials that heat or cool when stretched, compressed, magnetized or exposed to electric current.
Paul Motzki, a professor at Saarland University in Germany, leads an EU-funded group working with nickel-titanium. The metal cools when it is stretched and released, then returns to its previous shape. Motzki’s team is testing a lab prototype that he says could reduce room temperature by 5 to 10 degrees Celsius and operate more efficiently than current AC systems. The group expects to try the technology in new buildings within the next few years and is working with Irish company Exergyn, which is developing a refrigerant-free heat pump.
Other approaches are moving through prototypes. Brooklyn-based Mimic Systems is testing a semiconductor-based heat pump in a Vancouver apartment. Magnotherm, spun out of the Technical University of Darmstadt, uses magnetic fields and plans to test a refrigerator prototype in a German supermarket chain before turning to air conditioning. Barocal, a University of Cambridge spinoff, is working with plastic crystals that release heat when compressed and has raised $10 million in seed funding.
Cooling before machines
Lindsay Rasmussen of Third Derivative, a climate-tech accelerator founded by the Rocky Mountain Institute, said solid-state cooling remains early and unproven at scale. She said the field could move quickly if startups get capital and manufacturing partners. Large cooling companies such as Daikin and Samsung already dominate the market and monitor emerging technologies.
Oxford researcher Nicole Miranda and Voswinkel argue Europe still needs a cooling hierarchy: stop buildings overheating before installing more machines. That means trees, shade, reflective materials and natural ventilation first, with active cooling aimed at schools, hospitals and care homes. Paris has offered one model, expanding a network that circulates chilled Seine water through underground pipes to cool public buildings ahead of the 2024 Olympics.
The next European air-conditioning boom may use less refrigerant. It will still need planning, money and better buildings, which is the part no portable AC unit can fix.
This story draws on original reporting from WIRED.
