A recent development in window coating technology offers a solution to the age-old problem of excessive heat gain through windows while maintaining a clear view of the surroundings.
This innovative coating blocks heat-producing ultraviolet and infrared light while allowing visible light to pass through, regardless of the sun's position. It has the potential to significantly reduce cooling costs, particularly in hot climates, according to the research team.
"The angle between the sunshine and your window is always changing," said Tengfei Luo, the Dorini Family Professor for Energy Studies at the University of Notre Dame and the lead of the study. "Our coating maintains functionality and efficiency whatever the sun's position in the sky."
(Photo : LEON NEAL/AFP via Getty Images)
A Window Coating to Keep the View, Block the Heat
The brain behind this advancement is Tengfei Luo, the Dorini Family Professor for Energy Studies at the University of Notre Dame, in collaboration with his postdoctoral associate, Seongmin Kim.
Traditional window coatings are typically optimized for light entering at a 90-degree angle, which is not always the case, especially during peak sunlight hours.
To address this limitation, Luo and his team developed a transparent window coating consisting of ultra-thin layers of silica, alumina, and titanium oxide on a glass base. They added a micrometer-thick silicon polymer to enhance cooling efficiency by reflecting thermal radiation into outer space.
However, optimizing the coating for various angles of solar light required a different approach due to the numerous possible combinations. To tackle this challenge, the team turned to quantum computing, specifically quantum annealing.
This cutting-edge technique allowed them to determine the optimal configuration of layers that maximized visible light transmission while minimizing the passage of heat-producing wavelengths.
Like Polarized Sunglasses
The resulting coating not only maintains transparency but also reduces temperature by 5.4 to 7.2 degrees Celsius in a model room, even when light enters at oblique angles.
Moreover, the active learning and quantum computing methodology employed in creating this coating can be extended to design a wide range of materials with complex properties, offering possibilities beyond window coatings.
"Like polarized sunglasses, our coating lessens the intensity of incoming light, but unlike sunglasses, our coating remains clear and effective even when you tilt it at different angles," Luo said.
"This structure can be incorporated into existing windows in buildings or automobiles to reduce cooling energy consumption, and the active learning scheme can be applied to design materials with complex properties in general," the researchers wrote.
The study, titled "Wide-angle spectral filter for energy-saving windows designed by quantum annealing-enhanced active learning", was published in the journal Cell Reports Physical Science.
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