Breakthrough in Window Technology Leads to Significant Reduction in Energy Consumption.

Scientists from the University of Notre Dame have created a unique window coating that can filter heat-producing ultraviolet and infrared light while allowing visible sunlight, independent of the sun's location. The university was credited for this innovation.

A novel window coating has been developed that can lower indoor temperatures and energy bills by selectively filtering heat-producing sunlight, its efficacy remaining unaltered regardless of the direction of the incoming light.

Although windows allow light into the inside of buildings, they can also cause an increase in unwanted heat. This new window coating can filter heat-producing ultraviolet and infrared light while allowing visible sunlight, irrespective of the sun's position. The coating can be used on windows and automobiles that are already in use, and can decrease air conditioning cooling expenses by more than a third in hot climates.

“The angle at which the sun's rays meet your window is always shifting,” stated Tengfei Luo, the Dorini Family Professor for Energy Studies at the University of Notre Dame and the head of the research. “Regardless of the sun's position in the sky, our coating retains its performance and efficiency.”

A number of contemporary research on window coatings have been designed around light entering a room at a 90-degree angle. However, during noon which is usually the day's hottest segment, the sun's rays enter vertically installed windows at indirect angles.

Before now, Luo and his postdoctoral collaborator Seongmin Kim developed a see-through window coating by layering ultra-thin layers of silica, alumina, and titanium oxide onto a glass base. A silicon polymer just a micrometer thick was included to bolster the structure's ability to chill by reflecting thermal radiation into the atmospheric window, then out to space.

It was necessary to further enhance the sequence of the layers to ensure the coating could adapt to several sunlight angles. Despite that, Luo noted that a method of trial and error wasn't feasible due to the vast number of potential combinations.

For the sake of bringing the layers into an optimal arrangement, which would boost the transmission of visible light while reducing the passage of heat-producing wavelengths, the team utilized quantum computing—more specifically, quantum annealing—and experimentally confirmed their results.

The team's model resulted in a coating that maintained transparency and reduced temperature by 5.4 to 7.2 degrees Celsius (9.7 to 13 degrees Fahrenheit) inside a model room, even as light was transmitted from a wide range of angles. The laboratory's findings were recently published in Cell Reports Physical Science.

“Our coating, like polarized sunglasses, decreases the intensity of incoming light. But, in contrast to sunglasses, our coating remains clear and effective even when you tilt it at various angles,” commented Luo.

The active learning and quantum computing method that was developed to create this coating may be used in designing a wide variety of materials with complex properties.

Reference: “Wide-angle spectral filter for energy-saving windows designed by quantum annealing-enhanced active learning” by Seongmin Kim, Serang Jung, Alexandria Bobbitt, Eungkyu Lee and Tengfei Luo, 4 March 2024, Cell Reports Physical Science. DOI: 10.1016/j.xcrp.2024.101847