As blogged on TechnologyNetworks.com, engineers have designed a new system that can help cool buildings in crowded metropolitan areas without consuming electricity, an important innovation at a time when cities are working to adapt to climate change.
The system consists of a special material — an inexpensive polymer/aluminum film — that’s installed inside a box at the bottom of a specially designed solar “shelter.” The film helps to keep its surroundings cool by absorbing heat from the air inside the box and transmitting that energy through the Earth’s atmosphere into outer space. The shelter serves a dual purpose, helping to block incoming sunlight, while also beaming thermal radiation emitted from the film into the sky.
“The polymer stays cool as it dissipates heat through thermal radiation, and can then cool down the environment,” says co-first author Lyu Zhou, a PhD candidate in electrical engineering in the University at Buffalo School of Engineering and Applied Sciences. “This is called radiative or passive cooling, and it’s very interesting because it does not consume electricity — it won’t need a battery or other electricity source to realize cooling.”
“One of the innovations of our system is the ability to purposefully direct thermal emissions toward the sky,” says lead researcher Qiaoqiang Gan, PhD, UB associate professor of electrical engineering. “Normally, thermal emissions travel in all directions. We have found a way to beam the emissions in a narrow direction. This enables the system to be more effective in urban environments, where there are tall buildings on all sides. We use low-cost, commercially available materials, and find that they perform very well.”
Taken together, the shelter-and-box system the engineers designed measures about 18 inches tall (45.72 centimeters), 10 inches wide and 10 inches long (25.4 centimeters). To cool a building, numerous units of the system would need to be installed to cover a roof.