Seasonal window glass directs light and heat

Micro mirrors can be applied to regular window glass to direct winter light into the far corners of a room and block heat in the summer.

Swiss researchers have developed seasonal window glass that could make certain soft furnishings redundant. Office workers and home owners no longer have to block their own view in order to keep indoor space cool. Now, during the summer months, treated windows covered in a film containing micro mirrors bounce sunlight away from the building. EPFL scientists from the Laboratory for Solar Energy and Building Physics worked with Empa’s Laboratory for Advanced Materials Processing team. Micro-mirrors sit in a structure of laser-cut micro grooves, and film is wrapped around the entire object. The mirrors are made from Compound Parabolic Concentrator lenses. Designed especially for use in low visibility, the lens’ angle reflects the maximum amount of light. This is particularly useful during winter months of shorter days and less sun.

The smart mirrors detect the position of the sun in the sky. In summer months, the lenses bounce much more of the light, and thus heat, away from buildings. This reduces the high costs of artificial heating and cooling. Researchers say that visibility remains the same in windows using the coated glass. Developing cost-effective manufacturing processes is the next challenge for the team. A number of buildings across the Empa campus are testing the current version of the glass.

Smoggy cities are a global concern, and a number of window-based innovations are working to help maintain citizens’ health. In Singapore, researchers created a nano air filter that blocks UV rays while letting in air and light. The filter also helps to block unhealthy microbes. A startup in the United States built smart blinds that use solar energy to generate electricity. The blinds store electricity for future use and users monitor them via an app. What connections would help make a variety of smart, home-based appliances more efficient by helping them work together?