As climate change and heat waves intensify, a new eco-friendly material has been developed that can reduce building temperatures by up to 9 degrees without electricity.
Researchers from Zhengzhou University in China and the University of South Australia announced on the 24th that they have developed a "biodegradable cooling film" that reflects nearly all sunlight and emits internal heat into space. The research was published in the international journal "Cell Reports Physical Science."
◇Possibility of reducing cooling energy in Tibet by 20%
The newly developed cooling film can lower temperatures by an average of 4.9 degrees Celsius during the day and 5.1 degrees at night without using any electricity. The researchers explained that by attaching it to building exteriors or roofs, it can effectively address global warming and urban heat island phenomena. Simulation results showed that the film could reduce cooling energy by up to 20.3% annually in hot cities like Lhasa in the Tibet Autonomous Region of China.
The key component of the cooling film is polylactic acid (PLA), a plant-based plastic made from natural materials like corn starch that decomposes over time. The researchers applied a special structure that reflects 98.7% of light, designed to effectively block heat even under strong sunlight.
Most similar technologies developed so far have been criticized for causing environmental issues or lacking durability as they primarily use petroleum-based plastics or ceramic materials. This biodegradable film has been noted by researchers to withstand ultraviolet light and acidic conditions while maintaining its cooling function. In practical tests, the film showed performance in reducing temperatures by over 6.5 degrees after being exposed to strong ultraviolet light for 8 months and acidic conditions for 120 hours.
The researchers stated that this film was designed to be easily applicable in various places, including building exteriors or roofs, electronic devices, and agricultural greenhouses, so that it does not remain merely a laboratory result. They are currently reviewing the possibility of mass production, and it is expected to expand to fields such as medical cooling patches in the future.
Yangzhe Hou, a doctoral student at the University of South Australia who led the research, said, "This is a sustainable way to create a comfortable environment without relying on air conditioning" and explained that it is "a viable alternative to address urban heat island phenomena while reducing carbon emissions."
◇Temperature reduction technologies transformed by butterfly wings and AI glass
Guo Ping Wang, a professor at Shenzhen University in China, and his research team announced in the international journal "Optica" that they have developed a high-efficiency cooling film that can lower the internal temperature of vehicles, inspired by the structure of the Morpho butterfly.
The Morpho butterfly appears blue due to its microscopic photonic structure of wing scales that reflects certain wavelengths without pigments. The researchers imitated this by creating a film consisting of three layers. Below the top protective layer, they placed a translucent structure similar to the butterfly's wings, and beneath it, a silver mirror layer that reflects light.
By creating films in various colors, the experiments showed that the film maintained temperatures 2 degrees lower than the air temperature even under sunlight, and increasing the silver mirror layer could reduce temperatures by up to 10 degrees. In practical vehicle tests, vehicles with a film painted in regular blue paint reached temperatures of 75 degrees, while those with the butterfly-inspired film remained at 42 degrees. This technology can contribute to reducing cooling energy use in electric vehicles and increasing driving range.
Professor Kyunghee University and Tengfei Luo, a professor at the University of Notre Dame in the U.S., developed a "transparent window" that allows light to pass through while blocking heat using artificial intelligence (AI). The research team designed the glass substrate by stacking silicon dioxide, silicon nitride, and aluminum oxide, and overlaying a silicon oil film to allow 90% of visible light to pass through while reflecting 80% of infrared and ultraviolet light. AI was used to find the optimal combination of materials.
When this material was applied to building windows, the internal temperature dropped by 6.5 degrees, and cooling energy consumption could be reduced by up to 31%. The researchers explained that "the cooling windows can be applied to passenger cars and trucks, and the materials used can already be produced cheaply on a large scale, making commercialization possible."
References
Cell Reports Physical Science (2025), DOI: http://doi.org/10.1016/j.xcrp.2025.102664
Optica (2023), DOI: http://doi.org/10.1364/OPTICA.487561
ACS Energy Letters (2022), DOI:http://doi.org/10.1021/acsenergylett.2c01969