This material reflects heating sunlight away from buildings

Engineers from Stanford University have invented a revolutionary coating material that can help cool buildings by radiating heat away from the buildings and sending it directly into space.

The heart of the invention is an ultra-thin, multi-layered material that deals with light - both invisible and visible - in a new way.

This multi-layered coating also acts as a highly efficient mirror - preventing 97 percent of sunlight from striking the building and heating it up.

"We have created something that is a radiator that also happens to be an excellent mirror," said co-author and research associate Aaswath Raman.

The multi-layered material is just 1.8 microns thick, thinner than the thinnest aluminum foil.

The new material, in addition to dealing with infrared light, is also a stunningly efficient mirror that reflects virtually all of the incoming sunlight that strikes it.

"The result is photonic radiative cooling - a one-two punch that off-loads infrared heat from within a building, while also reflecting the sunlight that would otherwise warm it up. The result is cooler buildings that require less air conditioning," explained Shanhui Fan, professor in electrical engineering.

"Think about it like having a window into space," Fan added.

According to Raman, they designed the material to be cost-effective for large-scale deployment on building rooftops.

"Across the developing world, photonic radiative cooling makes off-grid cooling a possibility in rural regions, in addition to meeting sky-rocketing demand for air conditioning in urban areas," he said.

"Though still a young technology, it could one day significantly reduce demand for electricity," Raman concluded.

The research was reported in the journal Nature.