“Janus Emitter” – Scientists Engineer Passive Cooling Device for Surfaces and Enclosed Spaces

The bottom layer of the Janus emitter absorbs the heat inside the vehicle and emits it through the top layer to the atmosphere (indicated in blue), causing a temperature drop. The right image shows an experimental model that simulates a vehicle.
Credit: Young Min Song/GIST

Scientists engineer the first passive radiative device that absorbs heat from the inside of an enclosure and emits it on the outside.

If you have ever stepped into a car parked under the sun, you would be familiar with how hot it can get on the inside. This occurs because although sunlight can pass through the transparent windows, the thermal radiation re-emitted by the interior cannot, thereby creating a “greenhouse effect” and heating the inside of the car to temperatures as high as 82°C. Elderly people and children are at a particularly high risk of suffering heatstroke or hyperthermia at such temperatures.

This heat from a parked vehicle can be released by either spending energy in active cooling, which is not sustainable, or opening a window, which is not ideal on rainy days or when driving on a highway. Fortunately, scientists from Gwangju Institute of Science and Technology (GIST), Korea, have developed a new type of passive cooling technology to solve this issue.

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