Self-shading windows require no power

Posted By : Anna Flockett
Self-shading windows require no power

The idea to save energy by blocking the sunlight through windows is becoming more of a reality with the development of creating a window that can turn from transparent to opaque. Researchers at MIT have been able to see the future of smart windows with their ‘self-shading’ product. 

As the glass switches from clear to dark, or vice versa, very little, to no power at all is required to maintain the new system. It only requires electricity when the system needs to switch back again, unlike many other materials.

The quality of rapid response times and low power needs makes this new method far more effective than any other systems for causing glass to darken.

Mircea Dincă, MIT Professor of Chemistry was one of three to report on these results. He commented: “The other problem with existing versions of self-shading materials, it’s hard to get a material that changes from completely transparent to, let’s say, completely black.”

Using electrochromic materials, which can change their colour and transparency in response to an applied voltage; these are very different from photochromic materials, found in some glasses such as transition lenses. Dincă explained such materials tend to undergo a smaller change in levels of capacity and have a much slower response time.

Specifically the sponge-like material that is used, Metal-Organic Frameworks (MOFs) conducts both electrons and ions at high speeds. The MIT team was the first to harness them for their electrical and optical properties, even though these materials have been used for about 20 years for their ability to store gases within the structure. The difference is now, the new material, made by mixing an organic material and a metal salt, completely blocks or lets light pass through.

The new windows are reported to prove useful in several ways, from cutting down the costs of cooling and heating, to giving pilots a clearer view out of the cockpit window. However they could be very useful if fitted into residential or industrial windows, especially in hotter climates, where the technology was developed: The Masdar Institute, based in the United Arab Emirates, through a cooperative agreement with MIT.

Dincă stated the new windows have a lot of potential, to do much more than just preventing glare. “These could lead to pretty significant energy savings. You could just flip a switch when the sun shines through the window, and turn it dark.” He added, then again adjusting the windows to let in more sun light as the day progresses and save on artificial lights and energy. “Or even automatically make that whole side of the building go dark all at once.”

The next step for the team is to make a small-scale device for further testing, a one inch square sample to demonstrate the idea in action for investors in the product, and to determine the costs for the manufacturing and the windows themselves.

Smart windows are not the only way forward for this technology. Dincă believes that power displays, similar to displays like electronic ink (used in devices such as the Kindle and based on MIT-developed technology) could also use the material, just based on a completely different approach.

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