Scientists have developed a white paint that cools below ambient temperature even in direct sunlight. The study is published in the journal Cell Reports Physical Science.
Radiation cooling technology, which can be used in commercial paints, can be less costly to manufacture and passively reflects 95.5% of sunlight. In contrast, commercial “heat-repellent paints” currently on the market reflect only 80–90% of solar radiation and cannot reach temperatures below ambient.
In the summer, as well as in regions with a warm climate, conventional air conditioning systems operate in the offices. They require energy, generate excess heat, and contribute to the climate crisis.
Scientists have been developing paint for radiation cooling since the 1970s. Previously developed designs could not reflect enough sunlight to function as a viable commercial alternative to air conditioners.
To create a viable alternative to air conditioners, the team used calcium carbonate fillers instead of standard titanium dioxide particles. This helped to minimize the amount of UV light absorbed by the paint.
To demonstrate how well these modifications improved the paint’s cooling ability, the researchers conducted tests in West Lafayette, Indiana. The paint sample remained 10 degrees below the ambient temperature at night and at least 1.7 degrees below ambient temperature when the Sun was at its zenith.