Smart window design, seasonal temperature adaptation

Maintaining indoor temperature is energy intensive and accounts for 20-40% of national energy budgets in developed countries.

The new type of window can collect solar energy in winter and heat the house.

Researchers from the University of Pittsburgh (USA) and the University of Oxford (UK) have upgraded energy-saving windows to a 'new height'. Scientists have established new 'smart windows' that can capture solar energy in winter and heat homes. In summer, windows can reflect sunlight, keeping the house cool. The study was published in the journal ACS Photonics.

"These windows can change with seasonal demand," explains Nathan Youngblood, study author and assistant professor of electrical and computer engineering at the University of Pittsburgh. They absorb near-infrared light from the Sun in winter and turn it into heat in the building. During the summer months, the Sun can be reflected instead of absorbed'.

The window is made up of a layer of optical material less than 300 nanometers thick. In it, a thin active layer is made of phase transition materials, which can absorb the invisible wavelengths of sunlight and emit it as heat. The material itself can be 'converted'. Thanks to that, the wavelengths of light are changed.

'Importantly, visible light is transmitted almost equally in both states. So you won't notice a change in the window,' noted researcher Youngblood.

Materials can even be adjusted to allow for more precise temperature control. For example, 30% of materials lose heat. Meanwhile, 70% absorb and emit heat.

"We exploit how invisible wavelengths are transmitted or reflected to regulate temperature," said Harish Bhaskaran, professor in the Department of Materials at Oxford University, who led the study.

The researchers estimate that these windows will save 20-34% of energy annually compared to conventional double-glazed windows. To create and test the prototype, the researchers worked with Bodle

Technologies - a company specializing in the production of ultra-thin reflective films that can act as screens, by controlling color and light. In addition, Eckersley O'Callaghan - a leading engineer and architect and the thin film company Plasma App are also involved in window production.

Peiman Hosseini, CEO of Bodle Technologies, said: 'This work demonstrates another interesting optoelectronic application. The commercialization of glass panels still presents some significant challenges. However, I believe that this technology should be part of the future to tackle climate change."