As global temperatures rise, the urgency to combat heat is more pronounced than ever. The summer of 2025 witnessed severe heat waves that caused power outages across North America, Europe, and the Middle East. With climate change leading to increased reliance on air conditioning, the strain on energy grids is becoming a pressing issue. However, ancient principles combined with modern technology may provide a sustainable solution: radiative cooling. This process involves using paints, coatings, and textiles designed to reflect sunlight and dissipate heat, all without consuming additional energy.
Qiaoqiang Gan, a materials science professor at King Abdullah University of Science and Technology, highlights that radiative cooling is a phenomenon experienced in everyday life. Most objects absorb heat from sunlight during the day and release it at night, a process that can create condensation on vehicles parked outdoors. Historically, cultures in arid regions have leveraged this natural cooling effect for centuries, utilizing techniques such as constructing ice pools or cool roofs made with reflective materials. In recent years, advancements have been made in this field, especially with breakthroughs like the work of Aaswath Raman and his team at UCLA, who pioneered daytime radiative cooling using specialized photonic films that allow structures to cool significantly below ambient temperatures.
The current landscape is teeming with innovation, as startups like SkyCool Systems and Planck Energies race to bring effective cooling coatings to market. These new materials aim to reflect a substantial percentage of sunlight, with some achieving over 94% reflectivity in various climates. Initial pilot projects have shown promising results, demonstrating reductions in air conditioning needs by 15% to 20%. Furthermore, researchers are exploring the creation of reflective textiles that can provide personal cooling solutions for those most vulnerable to heat. However, challenges remain, as factors such as weather conditions, material longevity, and environmental concerns related to certain chemicals must be addressed. While radiative cooling presents an exciting avenue for mitigating heat, experts caution that it should complement, rather than replace, traditional cooling methods. As Gan aptly states, while shiny roofs may not solve all our climate challenges, they represent a significant step toward innovative, energy-efficient solutions.
Source: The paints, coatings, and chemicals making the world a cooler place via MIT Technology Review