08/13/2025
China’s paper-thin cooling film that works without electricity
In a breakthrough that could reshape how we cool our homes, vehicles, and electronics, Chinese engineers at Zhejiang University have developed an ultra-thin cooling film capable of lowering surface temperatures by up to 15°C without any electricity, fans, or refrigerants. This innovation, rooted in passive radiative cooling, is designed to work entirely on its own, offering a low-cost, sustainable alternative to conventional air conditioning systems. The potential implications for energy savings in hot climates are enormous, especially in regions where power supply is limited or unreliable.
The film’s structure is deceptively simple yet scientifically sophisticated. It is composed of layered polymer sheets coated with a dense arrangement of silicon dioxide nanoparticles. These nanoparticles serve two key functions simultaneously: they reflect an impressive 95% of incoming sunlight to prevent heat absorption and emit any absorbed thermal energy as infrared radiation directly into the cold sink of outer space. This dual mechanism means that even in the middle of a sweltering afternoon, the film actively cools itself and the surface beneath it.
Field tests conducted on rooftops under intense summer heat of 40°C showed striking results. Buildings equipped with the film maintained internal temperatures around 25°C without the help of air conditioning or mechanical ventilation. The cooling effect continued both during the day and at night, as the material radiated excess heat away. Its water-resistant and dustproof properties make it viable for long-term outdoor use, even in harsh weather conditions, without losing efficiency over time.
One of the most compelling advantages of this technology is its cost-effectiveness and scalability. At less than $2 per square meter to produce, it’s affordable enough for widespread deployment, from large industrial buildings to small residential homes. Unlike traditional cooling paints or coatings, the film is resistant to UV degradation, ensuring it remains effective over many years. Its flexibility also allows it to be applied as rolls, spray-on layers, or adhesive sheets on rooftops, walls, vehicles, and even portable electronics.
From a sustainability perspective, this cooling film offers a solution that not only reduces electricity consumption but also lessens greenhouse gas emissions associated with air conditioning systems. In rapidly urbanizing areas struggling with the “heat island” effect, where concrete and asphalt trap heat, the film could bring down ambient temperatures and improve public comfort. Data centers, often plagued by costly cooling demands, could also benefit from passive temperature regulation without increasing their energy footprint.
This technology’s versatility means it is not confined to urban infrastructure alone. In off-grid and disaster-prone areas where electricity is scarce, the cooling film could protect medical supplies, food storage, and emergency shelters from dangerous heat levels. Even in transportation, vehicles coated with the material could remain cooler while parked under the sun, reducing the load on air conditioning once the engine starts. Its low-maintenance nature makes it a practical fit for long-term deployment in remote locations.
China’s paper-thin cooling film stands out as one of the few innovations to combine scientific precision, environmental responsibility, and real-world practicality in a single solution. If scaled globally, it could transform how we handle heat management — replacing energy-hungry systems with a silent, self-powered material that works around the clock.
