During the summer of 2025, widespread heat waves strained power grids across North America, Europe, and the Middle East, highlighting the increasing need for sustainable cooling solutions. As global warming intensifies, reliance on air-conditioning units places a growing burden on energy infrastructure. However, a technology rooted in ancient practices, enhanced by modern materials science, offers a promising alternative: radiative cooling.

Radiative cooling leverages the natural process of heat dissipation, using specialized paints, coatings, and textiles to scatter sunlight and release heat without requiring additional energy input. Qiaoqiang Gan, a professor of materials science and applied physics at King Abdullah University of Science and Technology, explains that radiative cooling is a universal phenomenon. "Pretty much any object will absorb heat from the sun during the day and radiate some of it back at night," Gan said. This process explains why cars parked outside overnight often exhibit condensation; their metal roofs dissipate heat into the sky, cooling the surfaces below the ambient air temperature, leading to dew formation.

Humans have utilized radiative cooling for millennia. In desert regions of Iran, North Africa, and India, people historically manufactured ice by leaving pools of water exposed to clear night skies, capitalizing on radiative cooling to freeze the water. Modern advancements in materials science are now refining this ancient technique. Researchers are developing paints, coatings, and textiles engineered to maximize solar reflectance and thermal emittance. These materials can be applied to buildings, vehicles, and clothing to reduce heat absorption and promote cooling.

The implications of widespread radiative cooling adoption are significant. By reducing the demand for conventional air-conditioning, radiative cooling can alleviate pressure on power grids, lower energy consumption, and decrease greenhouse gas emissions. Moreover, these technologies can improve thermal comfort in regions lacking reliable access to electricity.

Current research focuses on enhancing the performance, durability, and scalability of radiative cooling materials. Scientists are exploring novel materials, such as metamaterials and photonic structures, to optimize solar reflectance and thermal emittance across a broad range of environmental conditions. The development of cost-effective and easily deployable radiative cooling solutions is crucial for widespread adoption and mitigating the impacts of global warming.