White paint reduces air conditioning demand

A team of researchers has developed a radiative cooling paint that keeps surfaces more than 1.7 °C cooler than their ambient surroundings (at noon).

Researchers at Purdue University have developed a radiative cooling paint that maintains a surface temperature lower than ambient under direct sunlight.  


“Heat-rejecting” paints are already available on the market. They reflect only 80-90% of sunlight. They cannot achieve temperatures below their surroundings. The paint developed at Purdue achieves a solar reflectance of 95.5% and surfaces coated with this paint have displayed temperatures up to 1.7°C lower than the temperature of the immediate environment at noon. 


This paint is made of calcium carbonate, a material that absorbs almost no ultraviolet rays due to its atomic structure. According to the researchers, this paint would be cheaper to produce than the alternatives currently available on the market, and it could save on the use of air conditioning (up to about one dollar a day).  


The article describing the tests conducted on the paint has been published in Cell Reports Physical Science and is available in open access