Silver-nanoring coating points to ‘self-regulating’ smart windows—without power or tinting

A new Danish research breakthrough could make buildings far more energy-efficient in the future. Researchers from Aarhus University’s Interdisciplinary Nanoscience Center (iNANO) have developed a light-responsive hybrid material based on so-called silver nanorings that automatically responds to solar intensity and regulates how much heat penetrates through windows.

The microscopic silver rings increasingly block near-infrared light as sunlight becomes stronger—without making the glass less transparent.

The technology functions without the use of power, sensors, or electronics—and could potentially be applied as a window coating in, for example, office buildings and modern residential buildings where large glass areas are common and heat radiation from the sun can be a challenge. This makes the solution particularly relevant at a time when energy consumption for cooling exceeds the need for heating in large parts of the world.

The technology is still in the research stage, but Aarhus University has already filed a patent application, which testifies to its commercial potential.

“We have developed a combination of materials whose optical properties change in response to sunlight. It allows heat to enter when the sun is low, but reduces heat radiation at midday—exactly when the need for cooling otherwise increases. And it all happens without any electricity,” says Ph.D. student Xavier Baami González.

The results have just been published in the journal Advanced Functional Materials.

“These types of solutions are crucial if we want to build in a more climate-friendly way without compromising on comfort and daylight. Our hope is that the hybrid material can eventually be integrated into smart window solutions and find its way into commercial use,” says Duncan Sutherland, who leads the research project.