As people grind through the dogs days of summer, September gives some relief to much of the United States. It feels good to open up the windows and finally allow fresh air through the house after continuously blasting the air conditioner. Researchers at the University of Stanford have been attempting to build a system that releases a building’s hot air without the aid of a powered cooling source. In simple terms, this means something really exciting: It's increasingly possible to cool buildings without electricity, meaning that keeping cool in the summer could get a whole lot more eco-friendly. And now, recent tests have shown how powerful it’s become.
Stanford originally developed the radiative sky cooling technology back in 2013. The idea was to create a process where buildings could be cooled without the need of an air conditioner. This technology would include a reflector that would transmit sunlight back into space without heating up too much. Doing so would defeat the purpose, of course, as the device would generate heat the building is trying to get rid of.
How does this work, step by step? First, a film is layered on the flat device that reflects 97 percent of the sunlight back into space. At the same time, the system will draw thermal radiation out of the building and pushes it into the Earth’s atmosphere. Even with the sun beaming directly onto a building, this process would have the ability to cool things off without the need of any external power source.
There’s been many attempts at this process, but Stanford finally figured it out through the use of nanostructured photonic materials. What are those? They’re microscopic objects in a device that manipulates how light is used and they’re able to both reflect light and radiate heat. Aaswath Raman, a co-author from the study back in 2013, explained that this device was “both higher performance and much more robust and practically relevant.”
Basically, these radiative sky cooling devices are similar in style to solar panels. Just like those are placed on a rooftop and can be produced on a large scale, Stanford has been able to develop this radiation technology in the same way. As a recent study from the university suggests, there now could be a way to cool off running water with these same panels.
Scientists tested out the theory by placing four of the cooling panels on top of a building and had water moving through a pipe below it. The structure of the building was similar to a two-story office building and it was tested in the hot air of Las Vegas. Water could be cooled by up to 9 degrees Fahrenheit lower than room temperature, and that in turn made the building cooler.
"If you have something that is very cold – like space – and you can dissipate heat into it, then you can do cooling without any electricity or work," Shanhui Fan, an author of this new study, told New Atlas. "The heat just flows. For this reason, the amount of heat flow off the Earth that goes to the universe is enormous." Energy savings range between 18 and 50 percent per day.
Potential for cooling buildings without the need for an additional energy source would significantly impact energy usage and would be less taxing on the electrical grid. At the moment, researchers are hoping to implement this technology in refrigerators and data centers under the new SkyCool Systems company they've founded.