Have you ever noticed that it can feel hotter in a city than in a rural area? Part of this is because all the dark paved surfaces in cities absorb the sun’s rays more than trees and natural spaces, making it feel warmer. A team of researchers from Purdue University is hoping to cool down cities with a new “super-white” paint that reflects 95.5 percent of sunlight.
Painting buildings white is one of many reflective strategies that have been used to cool buildings, but many are either too costly or have other environmental drawbacks. This newly developed white paint uses abundant calcium carbonate fillers to counter the absorption of ultraviolet light. It also uses particles of all different sizes in a concentration of 60% to more effectively scatter light.
Traditional white paints reflect between 80 and 90 percent of sunlight, so this new paint has extra heat-blocking powers. When used in a practical application on a building over two days, the painted area remained 1.7° C (3° F) cooler than the ambient temperature and, at night, the paint dropped 10° C (18° F) below the ambient temperature.
In future tests, the team is going to experiment with different paint patterns to see how application strategies affect cooling. This new technology could be used to cool buildings and reduce energy costs, as well as help, keep outdoor electrical systems from overheating.