smart windows

An international research team led by Nanyang Technological University in Singapore has invented a ‘smart’ window material that controls the transmission of heat without blocking the view through the window. The technology could help reduce the amount of energy needed to cool and heat buildings.

The new material can be the basis of an electrochromic window that can block or pass infrared radiation at the flick of a switch. Current electrochromic windows can be darkened when switched on and are found in many ‘green’ buildings as well as in many car mirrors. But these windows are only effective in blocking visible light so infrared radiation – meaning heat – still passes through them.

The new coating material blocks up to 70% of infrared radiation when switched on but still allows up to 90% of visible light to pass through. The material is a specifically designed composite nanostructure and utilizes advanced materials including titanium dioxide, tungsten trioxide, neodymium, niobium, and tin oxide. It is intended to be coated onto glass window panels and be activated by electricity when needed. The material was put through rigorous on-off cycles to assess its stability and durability and it appears to offer superior performance in that regard compared with current electrochromic technology.

The researchers also created a switchable system that helps control conducted heat, which is the heat from the external environment.

The combination of the two technologies could result in smart windows that control two types of heat transmission: infrared radiation and conduction heat. Such technology could help conserve energy used for the heating and cooling of buildings and could contribute to the future design of sustainable green buildings.

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Scientists invent ‘smart’ window material that blocks rays without blocking views

Photo, posted March 11, 2016, courtesy of Open Grid Scheduler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

It is estimated that air conditioners use about 6% of all the electricity produced in the United States for an annual cost of $29 billion. With rising temperatures, this expense is only going to get larger.

A significant part of the heat load in buildings arises from heat coming through windows. It turns out that for every square meter of window, about 500 watts of heat energy can be brought in by sunlight, equivalent to 5 old-fashioned light bulbs.

Researchers at MIT and the University of Hong Kong have developed a heat-rejecting film that can applied to a building’s windows that will reflect 70% of the sun’s incoming heat. The film is similar to transparent plastic wrap. It remains highly transparent at temperatures below 89 degrees Fahrenheit. Above that temperature, tiny microparticles embedded in the film shrink and the film becomes more translucent or frosted, still letting in a good amount of light, but rejecting a lot of heat.

There are already so-called smart windows on the market, similar to the electrochromic mirrors in cars that darken to prevent trailing headlights from blinding drivers. But that technology is not very effective in rejecting heat and it requires power to operate, which means you would have to pay to turn windows opaque.

Tests of the new film demonstrated its ability to reject heat and lower temperatures. The researchers estimate that if every exterior-facing window in a building were covered in the heat-rejecting film, the building’s air conditioning and energy costs could drop by 10%. Saving ten percent of tens of billions of dollars is no minor matter.

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See-through film rejects 70 percent of incoming solar heat

Photo courtesy of MIT researchers/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

A Smart Heat-Blocking Window | Earth Wise

An international research team led by Nanyang Technological University in Singapore has invented a ‘smart’ window material that controls the transmission of heat without blocking the view through the window. The technology could help reduce the amount of energy needed to cool and heat buildings.

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A See-Through Heat Shield

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