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Inspired by the thermal adaptation of penguins, the Janus film developed by Chinese researchers combines one side capable of absorbing 94.5% of solar energy with another that reflects more than 90% of light, paving the way for passive coatings in buildings, vehicles, electronics, and structures exposed to ice.
Inspired by penguins, the Janus film developed by Chinese researchers combines solar heating, radiative cooling, electromagnetic control, and resistance to water and ice, with the potential to reduce energy demand in buildings, vehicles, and electronics without additional electrical consumption.
Penguin-inspired film absorbs 94.5% of solar energy or reflects more than 90% of light, in an experimental Chinese technology created to alternate between passive heating and cooling in buildings, vehicles, electronics, and structures exposed to the weather.
Penguin-inspired material changes function depending on the side used
The development was conducted by Chinese institutions mentioned in the research. The proposal stems from a difficulty in thermal engineering: conventional surfaces usually fulfill one function.
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Coatings that help cool environments in summer can prevent the use of solar heat in winter. Absorbent materials do the opposite, heating well, but becoming inadequate when the temperature rises.
The new film attempts to overcome this limitation with a two-sided structure, called Janus. One side was designed to capture heat. The other was created to reject solar radiation.
The inspiration came from penguins, capable of surviving in extreme environments with insulating plumage, directional structures, and water protection. This combination helped scientists design an adaptive surface.
One side heats, the other cools
In tests, the side facing heating absorbed about 94.5% of the solar energy received. Under intense sunlight, the surface reached a temperature close to 87 °C in outdoor experiments.
The other side reflected more than 90% of the solar radiation and released heat to the exterior through radiative cooling. As a result, it was between 4 °C and 12 °C below the ambient temperature.
This behavior allows for imagining facades, coverings, or panels that alternate exposure according to the season. In the cold, the surface could favor solar heating. In the heat, it could reduce the entry of radiation.
The central advantage lies in passive operation. The material does not depend on motors, batteries, plugs, or additional electrical consumption to perform the thermal exchange between absorbing and reflecting heat.
Vanadium dioxide allows thermal and electromagnetic response
The key component of the film is vanadium dioxide, known for changing behavior when the temperature exceeds approximately 68 °C. At room temperature, it acts as an insulator. Above this point, it starts to behave like a conductive metal.
Researchers incorporated this compound into fiber-like microstructures within a flexible polymer layer. When the temperature rises, the particles form conductive paths and alter the electromagnetic response of the surface.
In practice, the same coating can allow the passage of wireless signals when cold and block or absorb microwaves when heated, depending on the tested frequency bands.
During experiments, microwave transmission dropped from 83.6% to 0.06% after heating the material in certain ranges. This characteristic broadens interest in electronics, communications, smart vehicles, and interference protection.
Energy efficiency in buildings comes to the center of application
The application in constructions is one of the most direct. In many urban areas, thermal conditioning accounts for about 50% of the global energy consumption associated with building use.
A coating capable of reducing the use of air conditioning and conventional heating would impact electrical grids, operational costs, and emissions. The material interacts with bioclimatic architecture.
The estimated potential savings reach 11 kWh per square meter per year. This number depends on usage conditions, surface orientation, and how the film would be applied on a real scale.
In cities affected by heatwaves, materials that reduce internal temperature without electricity can ease demand during peak hours. In cold regions, the absorbent side could help harness available solar radiation.
Water, ice, and outdoor use
Besides the thermal response, the film exhibits superhydrophobic behavior. Water droplets slide off easily, which helps keep the surface clean, reduces dirt adhesion, and limits ice formation.
In tests, freezing was delayed by 812 seconds. The accumulated ice melted in less than 18 minutes under moderate solar radiation, even with an external temperature close to -6 °C.
This property is of interest to exposed infrastructures, wind turbines, power lines, drones, and aviation, where ice increases costs and requires maintenance.
Electric vehicles also emerge as a possibility. Adaptive coatings could help maintain batteries within suitable thermal ranges, especially in extreme climates, where cold and heat reduce performance.
Aeronautics, satellites, and electronics are other possible fields, as many systems use separate layers for thermal insulation and electromagnetic shielding. In the Janus film, these functions are integrated into an ultra-thin structure.
Despite the potential, the technology remains in the experimental phase. Researchers are still working to improve large-scale manufacturing and assess resistance, durability, and performance in real-world conditions.
The advancement shows how observing penguins can guide engineering solutions to use less energy. The promise is not to immediately replace existing systems but to pave the way for smart, multifunctional, and passive materials.
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