2023-09-22 17:45:14
As summer turns to fall, or winter to spring, many people turn off the air conditioning and turn on the heat, or vice versa. But traditional heating and cooling systems consume a lot of energy and, because they typically run on fossil fuels, are not sustainable. By imitating a desert chameleon, a research team has now developed a cost-effective, energy-efficient coating that could keep buildings cool in summer or warm in winter without the need for additional energy.
Many desert creatures have adapted to survive in extreme environments with large daily temperature variations. For example, the Namaqua chameleon of southwest Africa changes color to regulate its body temperature when weather conditions change. When it is hot, this animal turns light gray to reflect sunlight and keep cool, but when it cools it turns dark brown to absorb heat. This unique capability offers a natural example of passive temperature control, a phenomenon that could be adapted to create more energy-efficient buildings. But many systems, such as cooling paints or colored steel tiles, are only designed to keep buildings cool or warm, and cannot change “mode.” Inspired by the Namaqua chameleon,
A team led by Yan Dong, from Nanyang Technological University in Singapore, sought to create a coating that changed color and adapted to changes in outside temperature.
To make the coating, the researchers mixed thermochromic microcapsules, which are microparticles, and specialized binders to form a suspension, which they sprayed or painted onto a metal surface. When heated to 20 degrees Celsius, the surface began to change color: from dark gray to light gray. When it reached 30 degrees Celsius, the clear film reflected up to 93% of solar radiation. The material showed no signs of deterioration even after being at more than 79 degrees Celsius for an entire day. The team then tested it along with three conventional coatings—plain white paint, a passive radiation cooling paint, and blue steel plates—in outdoor tests on small, doghouse-sized buildings for four hours. seasons of the year.
Achieving the most passive air conditioning possible in a building is a goal pursued for a long time by architects and other professionals. (Photo: Amazings/NCYT)
In winter, the new coating was slightly warmer than the passive radiation cooling paint, although both maintained similar temperatures in warmer conditions.
In summer, the new siding was noticeably cooler than the white paint and steel plates.
During the spring and fall, the new siding was the only system that could adapt to highly variable temperature changes, switching from heating to cooling throughout the day.
The researchers say this color-changing system could save a considerable amount of energy in seasonal areas because it is cheap and easy to manufacture.
El estudio se titula “Warm in Winter and Cool in Summer: Scalable Biochameleons Inspired Temperature Adaptive Coating with Easy Preparation and Construction”. Y se ha publicado en la revista académica Nano Letters, de la American Chemical Society. (Fuente: American Chemical Society)
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