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Smart windows equipped with controllable glazing can augment lighting, cooling and heating systems by varying their tint, saving up to 40 percent in an average building's energy costs.
These smart windows require power for operation, so they are relatively complicated to install in existing buildings. But by applying a new solar cell technology, researchers at Princeton University have developed a different type of smart window: a self-powered version that promises to be inexpensive and easy to apply to existing windows. This system features solar cells that selectively absorb near-ultraviolet (near-UV) light, so the new windows are completely self-powered.
"Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat," said Yueh-Lin (Lynn) Loo, director of the Andlinger Center for Energy and the Environment, and the Theodora D. '78 and William H. Walton III '74 Professor in Engineering. "We wanted the smart window to dynamically control the amount of natural light and heat that can come inside, saving on energy cost and making the space more comfortable."
The smart window controls the transmission of visible light and infrared heat into the building, while the new type of solar cell uses near-UV light to power the system.
"This new technology is actually smart management of the entire spectrum of sunlight," said Loo, who is a professor of chemical and biological engineering. Loo is one of the authors of a paper, published June 30, that describes this technology, which was developed in her lab.
Source: Princeton University
Journal Reference: Nicholas C. Davy, Melda Sezen-Edmonds, Jia Gao, Xin Lin, Amy Liu, Nan Yao, Antoine Kahn, Yueh-Lin Loo. Pairing of near-ultraviolet solar cells with electrochromic windows for smart management of the solar spectrum. Nature Energy, 2017; 2: 17104 DOI: 10.1038/nenergy.2017.104
(Score: 2) by lx on Monday July 03 2017, @08:18AM (2 children)
Infrared energy is light, not heat. It may produce heat, but so do visible light and UV.
I would expect better from an engineering professor at Princeton.
If popular science means dumbing down the science to the point of telling untruths then it's no wonder that scientific fact is seen as just another opinion.
(Score: 1, Funny) by Anonymous Coward on Monday July 03 2017, @10:28AM (1 child)
When you go into pedantic mode, do it right. First of all, there is no such thing as "infrared energy". There exists infrared radiation (which is electromagnetic radiation at a specific energy range), and that infrared radiation (like any electromagnetic radiation) carries energy. But it is not the energy that is infrared, it is the radiation.
Electromagnetic radiation is heat radiation if and only if it has a Planck spectrum. For temperature ranges typical on earth, that Planck spectrum has its maximum in the infrared part of the electromagnetic spectrum. An incandescent light bulb emits heat radiation with its maximum in the visible light range. And so does the sun.
No, it doesn't "produce heat". It may heat up other things (like any hot stuff does), and for heat radiation this heating up means heat exchange(!) between the photon gas and whatever is heated up by it.
(Score: 0) by Anonymous Coward on Monday July 03 2017, @04:36PM
If you are going to go full retardo-pedant you should get your facts right. An incandescent lightbulb emits about 90% of its radiation in the non-visible infra-red. This is why the greenies were so hot to replace them with CFLs.