a doctoral thesis presented at the eindhoven (netherlands) university of technology (tu/e) argues that switchable smart windows, which act as blinds during hot summer months and allow all the sunlight in during the winter, can significantly impact energy consumption.

this new technology will save as much as 12 percent in energy consumption.
(wikimedia commons)

the windows that were created at tu/e during the doctoral research reflect invisible infrared light but allows visible light to pass through, which is an improvement on past attempts at reflective windows that usually appear darker and are static, meaning that they have a cooling effect even in the winter when it is unwanted.

an article on the tu/e website explained, “the smart reflective windows developed by [doctoral candidate hitesh] khandelwal can keep out light with a wavelength of 700 nm to 1400 nm. this light is in the infrared range and invisible, but still contains nearly 50% of the energy from sunlight. the innovative thing about these windows is also that they can be switched on and off. users can use an on/off switch to do this or make use of an automatic option on the basis of temperature sensors, for example.”

to create the reflective layer of the windows, khandelwal incorporated organic liquid crystals, like those in smartphones, which can be arranged in certain ways to selectively reflect wavelengths of light.

the article continued, “applying an electrical charge, these molecules can be 'aligned' and reflect the sunlight. by adding different liquid crystal molecules, khandelwal was able to block nearly 100% of the sunlight between 700 nm and 1400 nm, yet the transparency of the visible light was still around 90%, comparable with the transparency of double glazing.”

the research insists that this technology could cut the energy consumption of buildings by as much as 12 percent.

the liquid crystal coating has been demonstrated between two panes of glass and research will continue towards developing a coating for single or existing panes.