Scientists have developed intelligent window coatings that can cool or heat indoor environments according to the climate

Scientists from Nanyang Technological University (NTU) in Singapore have recently developed an energy-saving glass that can heat or cool the interior of buildings according to environmental conditions. The glass is coated with a layer of coating that can react to constantly changing external temperatures and switch between heating and cooling as needed, potentially saving energy.

This type of glass does not have electronic components and works by utilizing light of different wavelengths responsible for heating and cooling.

In summer, this glass suppresses solar heating (near-infrared light) while promoting radiative cooling (longwave infrared) - a natural phenomenon where heat is emitted through the surface towards the cold universe - to cool the room. In winter, its effect is exactly the opposite, warming the room.

In laboratory tests, scientists use infrared cameras to observe the results. This type of glass allows for controllable heat to be emitted under various conditions, proving its ability to dynamically respond to changing weather conditions.

Windows are usually the least energy-efficient part of a building structure. According to data provided by the US Department of Energy, the energy consumption (heating and cooling) associated with windows in buildings accounts for approximately 4% of their total primary energy usage annually.

Although various technologies have been developed to alleviate their energy needs in cooling or heating, the team from Nanyang University of Technology believes that their technology is the first to achieve both.

Dr. Long Yi, the main researcher of this study, said, "Today, most energy-saving windows address the partial solar thermal gain caused by visible and near-infrared sunlight. However, researchers often overlook the radiative cooling of long wavelength infrared radiation. Although innovations focused on radiative cooling have been applied to walls and roofs, this function becomes undesirable in winter."

"Our team has demonstrated for the first time a glass that can respond favorably to two wavelengths, which means it can continuously self adjust and respond to temperature changes in all seasons."

As a proof of concept, scientists simulated and tested the energy-saving performance of their invention using climate data covering all residential areas worldwide. They found that the glass they developed showed energy-saving effects in both warm and cold seasons, with an overall energy-saving performance of up to 9.5%.

The first author of the study, Wang Shancheng, said, "The results demonstrate the feasibility of applying our glass in all types of climates, as it can help reduce energy use without being affected by temperature fluctuations during hot and cold seasons. This sets our invention apart from current energy-saving windows, which are often limited in areas with less seasonal changes."

In addition, the heating and cooling performance of their glass can be customized to meet the needs of the market and region.

Last year, another team announced transparent solar panels with record breaking efficiency, which could one day be placed on windows to generate renewable energy from buildings.

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