Allison Bailes on Energy Vanguard discusses a possible replacement for your air-conditioning:
The peer-reviewed journal Science this month published an article with a convoluted title, Scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling (behind a paywall; sorry), but a simple message. The researchers have developed a material that can radiate heat away at night and during the daytime. And it does so with an impressive cooling capacity.
The photo at the top of the article shows the material, a translucent film. It’s basically a plastic film with tiny silicon dioxide spheres embedded in it. (Silicon dioxide is what quartz is made of, the main component of a lot of the world’s sand, and used to make glass.) The spheres play a critical role in tuning the material to emit infrared radiation while not absorbing any of solar radiation that hits the material during the daytime. The paper goes into the the physics, including a discussion of phonon-enhanced Fröhlich resonances of the microspheres and extinction cross-sections, but I’ll let you read you that those details if you choose. …
What could turn out to be a really exciting discovery for the building community is their measured cooling capacity. They set up the film outdoors and measured how much heat it could radiate to the open sky. They used an electric heater to pump heat into the film and adjusted the rate to keep the film at the same temperature as the surrounding air. By adding just enough heat to keep the temperatures equal, the researchers say the “total radiative cooling power is therefore the same as the heating power generated by the electric heater.”
Interesting – and I’d love to stop hearing the air conditioning humming along.
