White roofs are one of those climate solutions that sound too good to be true. Compared to solar panels and electric cars, painting the roof of a building white is a suspiciously cheap, analog way to usher in a low-carbon future. But it works — white roofs reflect sunlight back into space rather than absorbing it, lowering building temperatures and reducing the need for energy-intensive air conditioning.
Although the technology for reflective paint is well established, there’s room for improvement. Scientists are still after the Holy Grail — a paint so white that it perfectly reflects the sun’s rays, creating a surface that’s cooler to the touch on a hot summer day than the air around it. And now, a team of researchers from Purdue University in Indiana claim to have come the closest yet.
Xiulin Ruan, the professor of mechanical engineering who led the research, said the average white paint on the market reflects between 80 and 90 percent of the sunlight that hits its surface, absorbing the rest. Their new paint reflects 98.1 percent.
It also pulls off another trick. Totally separate from interactions with sunlight, all surfaces, includi... Read more