32 rectangles neatly arranged in eight rows on the rooftop of a supermarket called Grocery Outlet in Stockton, California. Shimmering beneath a bright sky, at first glance they could be solar panels, but the job of this rig is quite different. It keeps the store from overheating.
After Grocery Outlet put the panels on the roof of the 25,000-square-foot building in late 2019, energy use by the store’s refrigeration system dropped by 15 percent. That amounts to almost $6,000 in savings per year. Luckily, Raman had nanotechnology at his disposal—a discipline that designs and produces materials through arranging molecules and atoms to behave exactly as needed.
“That was immediately pretty exciting,” Raman allows. In fact, the material was about 9°F cooler than the ambient air temperature, which was well above 80°F, a result he subsequently published inAround that same time, mutual friends connected him with Eli Goldstein, who was at Stanford finishing a doctorate in mechanical engineering.
“Temperatures are getting hotter, and that’s inherently going to mean that air conditioners and refrigeration systems become less efficient,” says SkyCool’s Goldstein. SkyCool is in discussions with the California State University system to use its tech to chill water that will be piped through the ceilings of three classrooms at Cal Maritime. But in dry climates, it might be enough to use the panels by themselves. “Imagine instead of having to buy an air conditioner in a small house in India or Africa, you could just put this on the roof,” says Goldstein.of radiative cooling, other startups have rushed into the field.