Super-amphiphobic coatings with sub-ambient daytime radiative cooling-Part 2: Cooling effect under real conditions

The cooling effect of a super-amphiphobic self-cleaning radiative cooling coating (RC coating) on various substrates was systematically studied under real working conditions and compared with that of conventional cool white coatings. Under direct sunlight, the surface temperature of the RC coatings was always below the ambient air temperature, even up to 12.9 degrees C on concrete, whereas that of the conventional cool white coatings on concrete reached 4.1 degrees C above the ambient air temperature. When the RC coatings were applied to industrial facilities such as carbon-steel-based substation cabinets, the temperatures of the coated ceiling surface and interior remained below the ambient temperature, yielding an interior temperature reduction of 13.7 degrees C relative to the temperature of an unpainted substation cabinet. When applied to outdoor living facilities, including safety helmets, sunshades, and Roman tents with open and closed curtains, the RC coatings could greatly improve the thermal comfort either by reducing the air temperature beneath the open facilities or by significantly lowering the interior temperature of the closed space of the living supplies. Upon application to concrete buildings, the RC coatings reduced the temperatures of the concrete surface, roof surface, and room interior by 25.7, 12.9, and 11.5 degrees C below the ambient air temperature, respectively, the decrease in the latter two being 9.8 and 4.8 degrees C, respectively, relative to the buildings coated with 0.88-solar-reflectance conventional cool white coatings. The measured sub-ambient cooling effect agreed with the theoretical prediction. In summary, RC coatings have wide application prospects in cooling energy conservation and emission reduction.

Automated summary

The study systematically investigated the cooling effect of a super-amphiphobic self-cleaning radiative cooling coating (RC coating) on various substrates and found that it can effectively reduce temperatures in industrial and outdoor living facilities, suggesting its wide application prospects.