Researchers urge passive cooling as air-conditioning demand climbs
A review led by UNSW Sydney says buildings need shading, reflective materials and ventilation to cut heat and ease pressure on power grids.
By Lucas Ferreira · Science & Environment Writer
3 min read
Rising heat is pushing more people toward air conditioning, but researchers warn that mechanical cooling alone will strain power systems and add to emissions. A global review led by UNSW Sydney Professor Mat Santamouris says passive cooling should become a core part of building design as cities prepare for hotter decades.
The review, published in Nature Reviews Clean Technology, examines technologies that reduce indoor heat without relying on electricity. According to the University of Sydney, the work covers radiative cooling materials, evaporative and combined radiative-evaporative systems, advanced solar control, external shading and personalized intelligent ventilation.
Cooling demand is rising fast
Air conditioning remains a life-saving tool during severe heat, Santamouris said, but greater dependence on it creates new problems for electricity networks and urban heat. The University of Sydney said European cities have recently faced some of their hottest recorded temperatures, putting cooling strategies under sharper scrutiny.
The review cites International Energy Agency data showing that cooling now accounts for nearly 10% of global electricity use. It also points to estimates that about 10 air conditioners are sold worldwide every second, while residential air-conditioning units are projected to number almost 5.6 billion by 2050.
At the same time, the researchers said many people in hot regions still cannot afford adequate cooling. That gap makes building design a public health issue as well as an energy issue, according to the review.
Passive measures as the first line of defense
Santamouris and co-author Dr. Konstantina Vasilakopoulou of RMIT argue that passive cooling should reduce heat before mechanical systems are needed. They do not call for replacing air conditioning, but for using it alongside better building design and lower-energy technologies.
Measures assessed in the review include reflective surfaces that send heat away from buildings, materials designed for super-cooling, hybrid systems that combine passive methods, exterior shading and ventilation tailored to occupants. The researchers said these approaches can lower indoor temperatures, reduce peak electricity demand and keep buildings safer when power fails.
In hot climates, pairing passive strategies with efficient design could cut cooling demand by as much as 80%, according to the review. The researchers said lower demand would also reduce stress on electricity grids during heat waves, when many households and businesses turn on cooling at the same time.
Policy changes urged
The review calls for stronger building standards and planning rules that account for future heat. Santamouris said buildings being constructed now are likely to remain in use in 2050 and beyond, so they should be designed for the climate expected during their lifetimes.
The researchers said governments should support passive cooling technologies, strengthen climate-responsive building codes and expand access to affordable cooling for lower-income communities. According to Santamouris, better design can lower costs, improve comfort and protect people most exposed to extreme heat.
The review frames cooling as a combined challenge for public health, energy security and climate adaptation. Its main conclusion is that cities will need both efficient air conditioning and buildings that keep heat out before electricity-powered systems have to take over.
This story draws on original reporting from Phys.org.