A team of researchers led by Andreas Schuler from the laboratory of solar energy and building physics in collaboration with the research team led by Patrick Hoffman of the laboratory of advanced material processing has developed a Smart window that functions concerning various seasons. It is a typical scenario in metros and cities where we can view skyscrapers featuring glass blinds everywhere to ward off heat, but the blinds impair the view. But the new Smart windows developed by the researchers reduce summer overheating and glare in summer and alternately allows high solar energy and daylight in winter.
How are the Smart windows made?
The team used a precision laser to create a microgroove structure on the surface of the film. The team then evaporated the micromirrors into the grooves that are covered by a polymer film. These mirrors so-called compound parabolic concentrator lenses (CPC) reflects sunlight without any effect on the visibility. Further, these mirrors reflected the light more efficiently and illuminated even the gloomiest corners. In the tests conducted by the team, the Smart windows displayed a light incidence of 60 degrees and also diverted 80 percent of the incident light.
So the mirrors spread the light evenly in horizontal direction illuminating even the farthest corners of the office or room. All this without a change in the view and minimising the transparency of the window. The team is now planning to upscale the process on a large scale producing millions of micromirrors that are precise and cost-effective. The new Smart windows will be installed in the NEST building on the EMPA campus in the Dubendorf.
Further, the mirrors are designed in such a way that they meet the seasonal requirements. In summer when the temperature is higher, the micro-mirrors are angled in such a way that they reflect the sunlight allowing only little light in summer. This is in contrast to winter where mirrors allow much of the light keeping the room warmer. So in future, we may witness buildings sporting Smart windows ditching the sun blinds, that not only saves electricity costs but also offers a clear view of the surroundings.