News in the smart window field: an energy-saving glass that regulates heating and cooling

Whether used for residential, commercial or industrial purposes, windows are an important element in buildings, illuminating interiors and allowing fresh air to flow through when opened. The problem is that they cause the dispersion of a great deal of heat energy: according to data from the US Department of Energy, energy usage for air conditioning in buildings depending on windows accounts for 4% of total annual primary energy consumption.

For this reason, the world of research is trying to find alternative and sustainable solutions to cut energy usage in buildings related to heating and cooling; until now, a new type of electrochromic glass has been experimented for windows, which darkens with the sun's rays, regulating the transmission of heat entering the building.

For the first time, Singapore's Nanyang Technological University has achieved crucial results in simultaneous modulation by creating window glass that is able to respond to outside changing temperatures of buildings and to regulate summer and winter air conditioning.

NTU researchers have developed an innovative material, made from layers of vanadium dioxide nanoparticles composite, plexiglass and a low-emissivity coating which, when coated on a glass window panel, self-adapts to the heating and cooling demand of indoor environments by exploiting the spectrums of light.

During summer, the glass suppresses solar heating (near infrared light) while boosting radiative cooling (long-wave infrared) to cool the room. In the winter, it does the opposite to warm up the room. The result? A glass window that reacts to changing temperatures and self-adapts to environmental comfort requirements, thus ensuring high energy saving in the building's heat consumption.

"This innovation bridges the gap between traditional smart windows and radiative cooling, paving the way for a new research branch to minimise energy consumption," said Professor Gang Tan, co-author of the research and professor at the University of Wyoming (USA).

The study supports NTU's 2025 strategic plan, launched this year by the Singapore University, which captures the ambitions and goals in education, research and innovation that NTU is willing to achieve over the next five years. This new research material is part of the specific actions the University is going to take, to address humanity's major sustainability challenges and to accelerate research into innovations that reduce the impact of human activities on the environment.