While the subject of white versus green roofs has been debated time and again, there isn't much discussion of how to best cool metal roofs and other structures.
Researchers at Johns Hopkins University's Applied Physics Lab have come up with a solution that not only cools down metal-roofed buildings, but can extend the life of any metal structure from naval ships to playground slides.
"Most paints you use on your car or house are based on polymers, which degrade in the ultraviolet light rays of the sun," says Jason J. Benkoski, Ph.D. "So over time you'll have chalking and yellowing. Polymers also tend to give off volatile organic compounds, which can harm the environment. That's why I wanted to move away from traditional polymer coatings to inorganic glass ones."Although glass has all of the right properties for cooling and protecting surfaces like light reflection and strength, Benkowski had to find a way around the short-comings of glass -- mainly that it's brittle. He modified potassium silicate to become a compound that when sprayed on a surface is strong and water-resistant. It also expands and contracts with metal surfaces so that it doesn't crack.
Also, because it doesn't contain any organic compounds, it should last far longer than any other paint coatings -- potentially hundreds of years.
The coating is mixed with white pigments to reflect all sunlight so that any surface it's applied to will remain at air temperature or cooler. Not only would this keep buildings cooler and the demand for air conditioning lower, but it would also prolong the life of any metal surface since exposure to extreme heat ages metal structures much more quickly.
For now, the paint is being developed for naval ships with testing starting in two years, but Benkoski expects that it will have far more commercial applications beyond that.
You can watch a video about this new coating below.