Is an Air-Conditioning Revolution Coming to Europe?

If you're reading this while the blinds are drawn against yet another heat wave and wondering whether it’s finally time to buy an air conditioner, you're far from alone. At the end of June, as temperatures climbed well above 40 degrees Celsius across Europe, shoppers in France literally forced their way into stores to snatch up portable fans and ACs before they sold out. Such scenes are likely to become more common. As the planet warms, the demand for cooling is rising worldwide. The International Energy Agency (IEA) predicts two-thirds of households could own an AC by 2050.

Politicians are, of course, turning ACs into a weapon in their broader culture wars. Far-right figure Marine Le Pen pledged to roll out air-conditioning across France if her party comes to power, while the British Conservatives vowed to overturn net-zero rules that restrict AC installation in new builds. On the left, the argument runs that air-conditioning would mainly benefit the rich and not those who need it most. It would also lock Europe into the same high-energy cooling spiral seen in the US and Asia. To date, only around 20 percent of Europeans have AC at home (and a mere 4 percent in the UK), compared with roughly 90 percent in the US, where electricity is considerably cheaper.

In Europe, air-conditioning is no longer just about comfort. It helps adults stay productive through extreme heat, and children concentrate in poorly ventilated schools. It helps people nod off when the air is still stiflingly warm long after sunset. It can even save lives. One research group estimated that air-conditioning prevented nearly 200,000 premature deaths among people over 65 in 2019 alone.

Europe is warming faster than any other continent, and countries that once had relatively mild summers are now experiencing increasingly frequent and intense heat waves. Research by Nicole Miranda and her colleagues at the University of Oxford suggests that countries such as the UK, Switzerland, Norway, and Finland could see some of the largest relative increases in heat exposure and cooling demand if global warming reaches 2 degrees C above preindustrial levels.

“We will need more cooling to protect people”, says Miranda, a senior lecturer in engineering and carbon reduction manager at the university. “The question is how to provide it in a way that is efficient, equitable, and smart. Not by panic-buying inefficient, energy-intensive portable ACs.”

June’s record-breaking heat wave offered a glimpse of what lies ahead. In northern Europe, homes and offices built to retain heat during long winters turned into ovens. A recent report by the UK's Climate Change Committee warns that by mid-century, over 90 percent of existing homes could overheat during severe heat waves. Even further south, centuries-old architectural adaptations—such as thick stone walls, white-painted façades, blinds and small windows designed to block the sun—are reaching their limits. People in Europe are already fed up with the extreme heat.

But simply adding more air-conditioning is not necessarily the answer—at least not in its current form. Because air-conditioning is built on a paradox: The machines that keep us cool are also heating the planet. The electricity they consume already accounts for roughly 3 percent of global greenhouse gas emissions, slightly more than the aviation industry. “We expect cooling to become one of the biggest drivers of electricity demand growth worldwide, along with data centers,” says Fabian Voswinkel, an energy-efficiency policy analyst at the IEA. With new units being installed worldwide every minute, electricity demand for space cooling could more than triple by 2050.

Solar power will help cut emissions, but it won’t clear air-conditioning’s bad reputation. Conventional ACs still run on a century-old principle: refrigerants cycle between liquid and gas to pull heat out of rooms and dump it outside. Manufacturers continue to refine the technology, but many of the refrigerants remain problematic. Fluorinated gases, for instance, have a global warming potential thousands of times greater than CO2 if they leak into the atmosphere. The EU therefore introduced a regulation in 2024 to phase them out gradually. “In the next few years, air conditioners and heat pumps using these gases won't even be able to be sold here”, says Voswinkel. But alternative gases bring their own trade-offs: Propane is highly flammable, while ammonia is toxic.

This impasse has led some scientists and companies back to the drawing board to ask: Instead of searching for a better refrigerant, what if air-conditioning systems didn’t need one at all? Their answer lies in materials that change temperature when exposed to external forces—a field known as solid-state cooling, which could revolutionize how we cool the air around us.

Paul Motzki, professor of smart material systems at Saarland University in Germany, heads an EU-funded scientific consortium focusing on nickel-titanium. When the metal is stretched and released, it snaps back to its original shape, absorbing heat from its surroundings and generating what is known as an elastocaloric cooling effect. In practice, the technology could be used to cool rooms by 5 to 10 degrees C and, according to Motzki, do so even more efficiently than conventional AC systems today. The team is currently testing the prototype in the lab, but expects to deploy it in new buildings within the next few years. If the technology works, it “could lead to disruption, even a paradigm shift, because the technology is so different from established cooling systems,” Motzki says. The group is collaborating with Irish company Exergyn, which is also developing a refrigerant-free heat pump.

Brooklyn-based Mimic Systems has developed a heat pump based on semiconductive materials capable of moving heat in and out of rooms when an electric current passes through. The prototype is being tested in an apartment in Vancouver. Magnotherm, a spinoff from the Technical University of Darmstadt, is using magnetic fields in refrigerators and will test its prototype in a German supermarket chain later this year before taking on air-conditioning. In the UK, University of Cambridge spinoff Barocal is experimenting with flexible plastic crystals that, when squashed and released in a pressurized chamber, release heat. The startup recently raised USD 10 million in seed funding.

Motzki says Europe is clearly at the forefront in solid-state cooling, including in efforts to bring the technology to market. “I see a major opportunity for Europe to achieve technological leadership all the way through to market maturity,” he adds. “Of course, this will all depend heavily on private capital and public funding.”

Lindsay Rasmussen sees the same potential. At Third Derivative, a climate-tech accelerator founded by the US nonprofit Rocky Mountain Institute, she works with startups such as Mimic Systems and Magnotherm on next-generation cooling. She stresses that solid-state cooling technologies are still in their early stages—promising, but unproven at scale. But “the space can move quickly if the right capital and partnerships are in place.”

The real question is not just whether these new technologies will work, but who will scale them and how quickly. History suggests the path won’t be linear, nor will it necessarily stay in Europe. Solar photovoltaics, for instance, began with research breakthroughs in Europe, moved into commercialization in the US, and ultimately scaled in Asia through vertically integrated supply chains. Solid-state cooling could follow a similar trajectory. As Rasmussen explains, innovations typically leave the lab and startups once they become commercially viable and are picked up by major manufacturers. Today’s cooling market is already dominated by multinational conglomerates such as Daikin and Samsung, which closely track emerging technologies and are ready to move quickly.

As the world rushes to cool itself, one reality risks getting lost: Installing more air conditioners will not, on its own, solve Europe's overheating problem. Many of its cities trap heat in tightly packed buildings and concrete streets, and the challenge is how to cool them without compromising the aesthetics that make them so distinctive.

Both University of Oxford researcher Miranda and IEA analyst Voswinkel call for a “cooling hierarchy”: The priority should be preventing buildings from overheating in the first place—through trees, shade, reflective materials, and natural ventilation. Active cooling should come later, focused on the places that need it most, such as schools, hospital wards, and care homes. From Paris, where he is based, Voswinkel points to one efficient example: Ahead of the 2024 Summer Olympics, the city expanded its district heating network to also distribute chilled river water through underground pipelines, cooling public buildings. “I think that these heat waves are making more and more policymakers realize that we have to face this new reality and make good plans,” he says.