Advanced Clear Window Heat Filter

As global climate change intensifies the summer heat, the demand for systems to cool buildings is growing. Now, scientists have created a transparent window covering that could reduce the temperature inside buildings, without wasting a single watt of energy and without cutting off light from outside like curtains and awnings do. Once the coating is placed, its presence goes practically unnoticed.

The filter has been created by a team including, among others, Seongmin Kim and Tengfei Luo from the University of Notre Dame in Indiana, USA, and Eungkyu Lee from Kyung Hee University in South Korea.

Refrigeration is estimated to account for about 15% of global energy consumption. That demand could be reduced with a window covering that blocks infrared light from the sun and other parts of the solar spectrum that typically pass through window glass and heat a closed room. Power consumption could be further reduced if the coating radiated heat from the window surface outward at a wavelength that passed through the atmosphere to outer space. However, it is difficult to design materials that can simultaneously meet these criteria and that can also transmit visible light, ie maintain the transparency of the window.

Seongmin Kim and his colleagues managed to design their filter, which meets all these conditions, using artificial intelligence and quantum computing.

More than just a filter, the coating can be defined as a transparent radiative cooling device.

A panel of the new coating, held between two fingers in the upper left area of ​​the image. As can be seen, the difference in visibility of the exterior landscape seen through the filter or with nothing in between is minimal. (Photo: adapted from ACS Energy Letters 2022, DOI: 10.1021/acsenergylett.2c01969)

The team built computer models of transparent radiative cooling coatings based on alternating thin layers of common materials such as silicon dioxide, silicon nitride, aluminum oxide or titanium dioxide on a glass base, topped with a polydimethylsiloxane film.

The researchers optimized the type, order and combination of the layers using an iterative approach guided by machine learning (a form of artificial intelligence) and quantum computing, which in this case allowed data to be stored using subatomic particles. This computational method performs optimization faster and better than conventional computers because it can efficiently test all possible combinations in a fraction of a second. Using this computational approach, it was possible to design a coating that, when manufactured, far exceeded the efficiency of conventional transparent radiative cooling coatings.

In hot, dry cities, the new coating could potentially reduce cooling energy consumption by 31% compared to conventional windows. The coating is also applicable to the windows of cars, trucks and other vehicles.

Seongmin Kim and his colleagues expose the technical details of their revolutionary heat filter in the academic journal ACS Energy Letters, under the title “High-Performance Transparent Radiative Cooler Designed by Quantum Computing.” (Font: NCYT by Amazings)