SolCold, a startup based in Herzliya, Israel, have come up with an ingenious method of cooling down surfaces that doesn’t require electricity! The technology is based on the counterintuitive principle of laser cooling, in which hitting specially designed materials with a laser can cool them by up to 150°C. It works because molecules in these materials absorb photons whose light is of one frequency while spontaneously re-emitting higher-frequency photons, which also carry more energy. Since energy is lost, the temperature of the material is reduced in the process. “It’s like putting a layer of ice on your rooftop which is thicker when there is more sun” says founder Yaron Shenhav.
The team of SolCold created a special paint made up of two layers: an outer layer that filters out some of the sun’s rays and an inner one that does the heat-to-light conversion, cooling itself below the ambient temperature. “Heat from a building could be absorbed and re-emitted as light,” he says. “As long as the sun is shining on it, it would be continuously cooled.”
So far, the material has been successfully tested in the lab, where the researchers have found that the effect is more pronounced on metal roofs than on concrete, and works best over rooms with low ceilings. Simulations show that a room on the top floor will feel up to 10°C cooler than with the paint applied if applied to a roof of a house than without the coating. The team will conduct pilot tests on buildings within two years.