New pigment-free coating stays 6°C cooler than surrounding air in desert sun
Columbia Engineering researchers developed a porous polymer coating that can cool surfaces below the surrounding air temperature without using electricity. The coating replaces conventional white pigments with nano-to-microscale air voids that reflect sunlight and release heat towards the sky. Tests showed the surface stayed about 6°C below ambient temperature in Arizona and 3°C below it in…
A new polymer coating developed by researchers at Columbia Engineering can keep structures significantly cooler than the surrounding air during hot weather. Unlike traditional air conditioners, which consume energy and may release harmful coolants, this coating relies on passive daytime radiative cooling (PDRC) to stay below ambient temperatures without external power sources or cooling agents.
The coating, which can be applied like paint, consists of microscopic air voids created using a solution-based process called phase-inversion. These air pockets reflect sunlight and allow the surface to radiate heat towards the cooler sky, resulting in a temperature drop of about 6°C in the Arizona desert and 3°C in the Bangladesh tropical climate during testing.
By replacing white pigments with these air voids, the coating achieves high solar reflectance (over 96%) and thermal emittance (around 97%), enabling it to remain much cooler than its surroundings even under varying atmospheric conditions.
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