New paint cools buildings using light from the sun

A new paint is being developed that could actively cool buildings using laser cooling properties adapted for sunlight.

With global warming heating up, and energy costs continually on the rise, engineers and researchers are constantly working on ways to cool the air without warming the planet. Ideas have included painting roads with a paint that reflects sunlight and a paint that produces hydrogen gas for use as fuel. Now, SolCold, a startup based in Herzliya, Israel, has come up with a way to cool buildings without using electricity. 

SolCold’s technology is based on the principle of laser cooling, in which firing lasers at certain materials can cool those materials by up to 150°C. Laser cooling works because the materials absorb photons at one frequency, while at the same time emitting higher-frequency photons which carry more energy. In this process energy is lost, which lowers the temperature of the material.

SolCold founder Yaron Shenhav and his team have created a paint that absorbs sunlight instead of light from lasers. The paint is made up of two layers – an outer layer which filters out light in frequencies that do not aid in cooling, and an inner layer that can absorb the remaining photons and give off light. Lab tests have found that when the paint is applied to a metal roof, it can cool the room underneath by up to 10°C. Pilot tests on buildings will be conducted within two years. The new paint will cost around USD 300 to coat 100 square metres.