Cooling buildings with air conditioning systems could consume large amounts of energy. A team of engineers, however, has developed a new system that can do this without the need for electricity.

Cooling Buildings Without Electricity

The system is made of an inexpensive polymer/aluminum film installed inside a box at the bottom of a solar "shelter." This film helps keep the surroundings cool by absorbing heat from the air inside the box. It then transmits that heat energy through the Earth's atmosphere into outer space.

The shelter has two purposes: it helps block incoming sunlight, and it also beams thermal radiation emitted from the film into the sky. It does these without requiring electricity.

"The polymer stays cool as it dissipates heat through thermal radiation, and can then cool down the environment," said Lyu Zhou, from 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."

Qiaoqiang Gan, also from the University of Buffalo, said that thermal emissions normally travel in all directions. One of the things that make the system special is its ability to purposely direct thermal emissions toward the sky.

This allows the system to be more effective in urban areas with tall buildings on all sides.

Numerous units of the shelter-and-box system — each measuring about 18 inches tall, 10 inches wide, and 10 inches long — would be installed to cover a roof to cool a building.

Addressing Challenges In Daytime Cooling

The engineers behind the tech said that system addresses a challenge in daytime cooling, when the sun is shining. The system helps prevent rooftops from heating up. It also uses materials that do not absorb solar energy.

Zhou and colleagues said that when placed outside during the day, the system can help reduce the temperature of a small, enclosed space by up to 6 degrees Celsius. At night, it can reduce heat to about 11 degrees Celsius.

Potential Impact On Energy Consumption

The innovation comes at a time when cities are working to adapt to a warming world brought by climate change.

"This practical strategy that cools without electricity input could have a significant impact on global energy consumption," Zhou and colleagues wrote in their study, which was published in the journal Nature Sustainability on Aug. 5.

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