Cool walls with green, energy-efficient coating

BEIJING, July 11 (Xinhua) -- Chinese researchers have developed a type of eco-friendly daytime passive radiant refrigeration material that can cool building surfaces and apparently save energy.

Air conditioning refrigeration in buildings during summer accounts for about 15 percent of the total energy consumption globally, according to a report from Science and Technology Daily.

Previously, foreign researchers have experimentally achieved zero-energy radiant cooling to reduce the surface temperature under direct sunlight lower than the environment temperature.

This successful experiment paved the way for the industrialization of the new surface cooling method. In 2021, researchers from the China South Architecture under the China State Construction developed the environmentally friendly radiant paint and made its production and application a reality.

The daytime passive radiation refrigeration coating can reportedly reflect 98.6 percent of solar heat and save 40 to 71 percent of energy consumption for the buildings' air-conditioning and refrigeration in summer.

Compared to silver-plated cooling materials with radiation function, the new coating reduces the cost per square meter by 63 percent, said Zhang Weidong, a researcher with the China South Architecture.

Daytime radiant cooling materials come in dazzling white color, causing varying degrees of light pollution. Zhang and his team have developed the material in red, yellow, blue, orange and grey, solving the contradiction between surface color and solar reflectivity.

A transparent super-hydrophobic and super-oleophobic self-cleaning layer is compounded on the refrigeration coating to resist stains, according to the researchers.

The new refrigeration coating has been used on concrete constructions, mobile communication base stations, grain warehouses at room temperature and traffic facilities.

The refrigeration coating used on mobile communication base stations located in different climatic zones can save 30 to 73 percent of energy consumption of air-conditioning refrigeration, as well as protect the equipment and prolong their service life.

Thanks to this coating, the grain warehouses at room temperature can reduce the internal temperature of wheat by 7.1 degrees Celsius, even in late spring or early summer, to effectively reduce evaporation loss and pest damage, prevent grain condensation and mildew, and delay grain aging.

The China State Construction is promoting the application of the refrigeration coating in energy storage stations, data centers, grain warehouses in low temperature, refrigerated warehouses and oil and gas storage tanks, according to the report.