Considering the fact that residential air-conditioners consume up to 15% of the total energy used in housing buildings across the United States, Stanford University engineers have come up with a paint coating solution that reflects sunlight, or rather directs heat away from the house into outer space, and as well cools the house and the planet at a go.
The team of researchers developed an ultrathin, multilayered, nanophotonic material that is capable of reflecting the sun’s heat away from buildings in order to cool it, while also directing internal heat from inside the building to the outside to effect a natural cooling system. Just like a mirror would reflect sunlight, the paint coating reflects away sunlight heat and draws a building’s interior heat outside. The building is cooled, and the planet is also cooled.
The researchers have called the system a “photonic radiative cooling”, and they achieved the breakthrough with a coating that is made up of silicon dioxide (SiO2) and hafnium dioxide (HfO2) – set on a thin layer of silver. These materials are then arranged into seven layers that is 1.8 microns thick which is actually thinner than aluminum foil – and with the ingenuity of the scientists, this material has the ability to reflect sunlight and also conduct infrared rays.
Professor Shanhui Fan, leader of the team, opines that “Every object that produces heat has to dump that heat into a heat sink. What we’ve done is to create a way that should allow us to use the coldness of the universe as a heat sink during the day.” Actual tests prove that the coating is capable of reflecting away 97% of incoming sunlight and when this is combined with the photonic radiative cooling system, then the material becomes cooler than the surrounding air by about 9oF or 5oC.
With tests carried out in the laboratory, the scientists face some little challenges before making this coating paint available for commercial use. They are still working to make it applicable for residential use, and as well as work out a cost effective way for its commercial production.