Engineers have designed a 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 — installed in a box at the bottom of a specially designed solar “shelter.” The film helps keep its surroundings cool by absorbing heat from the air inside the box and transmitting the 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. This radiative or passive cooling does not consume electricity or battery power.
The system purposefully directs thermal emissions toward the sky. Normally, thermal emissions travel in all directions; the new system beams 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. The shelter-and-box system measures 18 × 10 × 10". To cool a building, numerous units of the system would need to be installed to cover a roof.