As temperatures rise around the world, air conditioning is saving lives. But a growing reliance on it is also placing unprecedented pressure on electricity grids, increasing greenhouse gas emissions and making cities even hotter.

A global review led by UNSW Sydney's Professor Mat Santamouris AM—an expert in innovative heat mitigation technologies and strategies for cities—argues that keeping buildings cool without relying solely on air conditioning will be critical for adapting to climate change.

Published in Nature Reviews Clean Technology, the review examines the latest advances in passive cooling technologies, from emerging materials for radiative, evaporative and combined radiative/evaporative cooling to sophisticated solar control systems and personalized intelligent ventilation technologies that can help buildings shed heat without consuming electricity.

Professor Santamouris says passive cooling should no longer be viewed as a niche architectural feature, but as essential infrastructure for a warming world.

"Air conditioning saves lives and will remain essential during extreme heat," he says. "But we cannot air-condition our way out of climate change. If every building depends entirely on mechanical cooling, we create enormous pressure on electricity systems while adding even more heat to our cities."

Demand for cooling is soaring
The review highlights the rapid growth in cooling demand worldwide. Global electricity consumption for cooling has reached almost 10 percent of total electricity use, with around 10 new air conditioners sold every second. By 2050, the number of residential air-conditioning units is projected to increase to almost 5.6 billion worldwide.

At the same time, billions of people living in hot climates still lack access to affordable cooling.