Researchers created a high-tech cooling device that uses mirrors to beam heat away from buildings and into space.
The invention relies on a groundbreaking material that is ultra-thin and deals with light in an original way, Stanford University reported.
The material can deal with both invisible (infrared radiation) and visible light (such as sunshine). The new method, dubbed photonic radiative cooling, offloads infrared heat and reflects sunlight from buildings. The method could allow for cooler buildings that require less air conditioning. The multi-layered material acts as mirror that can prevent 97 percent of sunlight from striking a building.
"This is very novel and an extraordinarily simple idea," said Eli Yablonovitch, a professor of engineering at the University of California, Berkeley, and a pioneer of photonics who directs the Center for Energy Efficient Electronics Science. "As a result of professor Fan's work, we can now [use radiative cooling], not only at night but counter-intuitively in the daytime as well."
The material is an impressive 1.8 microns thinner than aluminum foil. It is composed of seven layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. The layers vary in thickness, and can radiate infrared rays at a frequency that lets them pass into space without warming the building.
The cost-effective material could reduce buildings' energy demand by as much as 15 percent.
"This team has shown how to passively cool structures by simply radiating heat into the cold darkness of space," said Nobel Prize-winning physicist Burton Richter, professor emeritus at Stanford and former director of the research facility now called the SLAC National Accelerator Laboratory. "Across the developing world, photonic radiative cooling makes off-grid cooling a possibility in rural regions, in addition to meeting skyrocketing demand for air conditioning in urban areas."
The findings were published in a recent edition of the journal Nature.
