This California company wants to make modern AC obsolete

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.

Tilted toward the sun, the panels absorb almost none of the warmth beating down on them; they even launch some into space, improving the performance of the systems that keep things inside cold. The feat relies on a phenomenon called radiative cooling: Everything on Earth emits heat in the form of invisible infrared rays that rise skyward. At night, in the absence of mercury-raising daylight, this can chill something enough to produce ice. When your car’s windshield frosts over, even if the thermometer hasn’t dipped below freezing? That’s radiative cooling in action.