IIT Guwahati team develops smart window materials

New Delhi, May 25

Researchers at the Indian Institute of Technology (IIT), Guwahati have developed smart window material for automatic climate control of buildings.

According to the researchers, the smart window material designed by them can effectively control the amount of heat and light passing through it in response to an applied voltage and would ultimately help in developing efficient automatic climate control.

The results of the study have recently been published in the journal, Solar Energy Materials and Solar Cells.

“There has been increased attention to sustainable architectural designs for better light and heat management in buildings in recent years, and deploying smart windows is the first step for such structures,” said Debabrata Sikdar, Assistant Professor, Department of Electronics and Electrical Engineering, IIT Guwahati.

“Conventionally, window designs are static — they are predesigned for specific climatic conditions. The emergent smart windows, on the other hand, can dynamically adjust the amount of light and heat radiation entering a building in response to external stimuli, thus conserving the building’s energy,” Sikdar added.

Noting that the design of smart windows that are tuneable for all-weather conditions is challenging, the team claimed that it has designed smart window ‘glasses’ using noble metals as well as their relatively inexpensive alternatives that can dynamically control the intensity of transmitted solar radiation, depending upon the weather/climate conditions.

“We have proposed an electro-tuneable glass made of two ultra-thin metal layers sandwiching an electro-optic polymer whose refractive index can be changed by applying a small voltage, which allows filtering of visible and infrared radiation,” explained Ashish Kumar Chowdhary, research scholar, IIT Guwahati.

The researchers used this design to perform simulation studies to understand the light and heat transmission properties in response to the applied voltage. They initially considered gold and silver as the metal layers, but later tested their model with cheaper alternatives such as copper, and transparent semiconductor such as indium tin oxide.

“At present, the COVID-19 pandemic has imposed an unprecedented risk of cross-infections through aerosols transmission in public buildings such as healthcare centres, offices, transportation systems, workshops, laboratories and food storage facilities, where central air-conditioning systems are in use.

“We believe that our smart windows can provide an alternative solution for maintaining ambient indoor temperature and lighting inside a building or a vehicle by integrating those with usual glass windows or walls, thereby reducing the need of air-conditioning systems,” Sikdar said.

The researchers acknowledge that since the optical response of these types of smart glasses is critically linked to the surface smoothness and other physical properties of the layers, it is important to further analyse the effect of these properties on the performance of the glass. PTI