Researchers from Zhengzhou University (China) and the University of South Australia have developed a biodegradable metafilm made of polylactic acid (PLA) that passively cools buildings without electricity. In tests, the film reflected nearly 99% of incoming solar radiation and lowered surface temperatures by up to 9.2 °C during peak sunlight. It also helps buildings shed heat through longwave (infrared) emission, allowing interiors to stay cooler even under direct sun exposure.
Durability tests showed that the film continues to work well even after extended exposure to UV light and acidic conditions. Simulations suggest that in very hot cities, using this film on building exteriors could reduce annual energy consumption—especially from air conditioning—by up to 20%. The film is fully biodegradable and fabricated using a low-temperature process, making it a promising green alternative to conventional cooling materials. More