A new high-tech material, developed by engineers from the University of Stanford, cools buildings by reflecting sunlight and radiating internal heat, directing both out into space.
Led by electrical engineering Professor Shanhui Fan and research associate Aaswath Raman, the team of engineers produced the ‘double-hit’ method, which they refer to as “photonic radiative cooling”.
The material is just 1.8 microns thick - thinner than the thinnest aluminum foil - and is made up of seven layers of silicon dioxide and hafnium oxide on top of a thin layer of silver.
The layers are different thicknesses, engineered to radiate infrared rays at a frequency that lets them pass out of the building and into the atmosphere without warming the surrounding air.
The coating also acts as a highly efficient mirror, reflecting 97 percent of the sun’s rays from its surface.
Combined, it provides a highly efficient means of helping cool a building passively, reducing the need for air conditioning.
The researchers are now working out how to turn the material into a product that can be sprayed onto building surfaces and rooftops for cost-efficient, large-scale deployment.
Courtesy Stanford University
