Air conditioning is not enough to keep people cool — can scientists find an alternative?

 

As large swathes of Europe and Asia swelter through record heatwaves this summer, discussions have centred around an obvious way to keep people cool: more air conditioners. Popular in high-income countries such as the United States, Japan and Australia, these units are less common in homes in Europe or in low-income countries. But air conditioners are expensive to run, use vast amounts of energy and generate heat, so installing them in every home that needs one is not the answer, say scientists. Instead, they say that, over the past few years, there have been advances in materials that passively cool buildings, offering a solution without the drawbacks.

Cooling buildings accounts for nearly 10% of electricity use globally, according to a review published earlier this month in Nature Reviews Clean Technology1. That is expected to grow as heatwaves become more frequent, intense and long-lasting. By 2050, the electricity needed to cool buildings globally is expected to have increased by 210% above levels recorded in 2024, with greenhouse-gas emissions from air conditioning likely to triple over the same period.

Matthaios Santamouris, an architecture researcher at the University of New South Wales in Sydney, Australia, who co-authored the review, says air conditioning can be life-saving for people who are at high risk of dying from extreme heat, including those aged more than 65, but that the technology has several drawbacks. During temperature spikes, when there is a surge in air-conditioner use, the sudden demand for electricity puts pressure on the grid, leading to blackouts that endanger people vulnerable to heat stress.

Air conditioning also raises temperatures in cities, says Negin Nazarian, an urban climatologist at the University of New South Wales. Split systems, in which an air-conditioning unit cools down an individual room, work by extracting heat from the building and “dumping it right next door”, into the surrounding environment, Nazarian adds. This creates a “vicious loop”, she says, in which temperatures outside increase, prompting greater use of air conditioning to cool indoor spaces.

Read More: https://www.nature.com/articles/d41586-026-02273-2