Energy-saving glass “adapts” to heating and cooling demand

An international research team led by scientists from Nanyang Technological University, Singapore (NTU Singapore) has developed a material that, when applied to a glass window panel, can effectively adapt to heat or cool rooms in different climatic zones of the world, helping to reduce energy consumption.

Developed by NTU researchers and reported in top scientific journal Science, the first glass of its kind automatically reacts to temperature changes by switching between heating and cooling.

Self-adaptive glass is developed using composite layers of vanadium dioxide nanoparticles, poly(methyl methacrylate) (PMMA) and a low-e coating to form a unique structure that could simultaneously modulate the heating and cooling.

The newly developed glass, which has no electrical components, works by harnessing light spectra responsible for heating and cooling.

During the summer, the glass suppresses solar heating (near infrared), while stimulating radiative cooling (long wave infrared) – a natural phenomenon where heat radiates through surfaces to the cold universe – to cool the room . In winter, it does the opposite to warm the room.

In laboratory tests using an infrared camera to visualize the results, the glass allowed a controlled amount of heat to emit under various conditions (ambient temperature – above 70°C), proving its ability to react dynamically to weather conditions changing.

New glass regulates both heating and cooling

Windows are one of the key elements of a building’s design, but they are also the least energy efficient and most complicated part. In the United States alone, the energy consumption associated with windows (heating and cooling) in buildings represents approximately 4% of their total primary energy consumption each year, according to an estimate based on data available from the United States Department of energy.

While scientists elsewhere have developed sustainable innovations to mitigate this energy demand – such as the use of low-emissivity coatings to prevent heat transfer and electrochromic glass that regulate solar transmission from entering the room by tinting – none of the solutions have been able to modulate both heating and cooling at the same time, until now.

The study’s lead researcher, Dr Long Yi from the NTU School of Materials Science and Engineering (MSE), said: “Most energy-saving windows today address the energy gain part of the solar heat caused by visible and near-infrared sunlight. However, researchers overlook radiative cooling in the long-wavelength infrared. While innovations focused on radiative cooling have been used on walls and roofs, this feature becomes undesirable in winter. Our team has demonstrated for the first time a lens that can respond favorably to both wavelengths, meaning it can continuously self-adjust to react to a change in temperature through all seasons.”

With these features, the NTU research team believe their innovation provides a practical way to save energy in buildings, as it does not rely on any moving components, electrical mechanisms or blocking views to operate.

To improve window performance, the simultaneous modulation of solar transmittance and radiative cooling is crucial, said co-authors Professor Gang Tan of the University of Wyoming, USA, and Professor Ronggui Yang of Huazhong University of Science and Technology, Wuhan, China, which led the building’s energy-saving simulation.

“This innovation fills the missing gap between traditional smart windows and radiative cooling by opening up a new research direction to minimize energy consumption,” said Professor Gang Tan.

The study is an example of groundbreaking research that supports the NTU 2025 strategic plan, which aims to address humanity’s grand sustainability challenges and accelerate the translation of research discoveries into innovations that mitigate human impact. on the environment.

A useful innovation for a wide range of climate types

As a proof of concept, the scientists tested the energy-saving performance of their invention using simulations of climate data covering all populated regions of the globe (seven climate zones).

The team found that the glass they developed exhibited energy savings in both hot and cold seasons, with an overall energy saving performance of up to 9.5%, or ~330,000 kWh per year (estimated energy required to power 60 homes in Singapore for one year) less than commercially available low-e glass in a simulated mid-rise office building.

The study’s first author, Wang Shancheng, who is a researcher and former doctoral student of Dr. Long Yi, said, “The results prove the viability of applying our glass in all types of climates as it is capable of help reduce energy consumption regardless of heat. and cold seasonal temperature fluctuations. This distinguishes our invention from current energy saving windows which tend to find limited use in regions with less seasonal variation.

In addition, the heating and cooling performance of their glass can be customized according to the needs of the market and the region they are intended for.

“We can do this by simply adjusting the structure and composition of a special nanocomposite coating applied to the glass panel, allowing our innovation to potentially be used in a wide range of heat control applications, not limited to windows,” Dr Long Yi said.

Providing an independent perspective, Professor Liangbing Hu, Professor Emeritus Herbert Rabin, Director of the Center for Materials Innovation at the University of Maryland, USA, said: “Long and his colleagues have achieved the development original of smart windows capable of regulating proximity infrared sunlight and long-wave infrared heat. The use of this smart window could be very important for energy saving and decarbonization of buildings.

A Singapore patent has been filed for the innovation. In the next steps, the research team aims to achieve even higher energy saving performance by working on the design of their nanocomposite coating.

The international research team also includes scientists from Nanjing Tech University, China. The study is supported by the Singapore-HUJ Alliance for Research and Enterprise (SHARE), under the Campus for Research Excellence and Technological Enterprise (CREATE) program, the Minster of Education Research Fund Tier 1 and Sino -Singapore International Joint Research Institute.