Cooling Performance\nof TiO<sub>2</sub>‑Based\nRadiative Cooling Coating in Tropical Conditions

The cooling power\nof radiative cooling (RC) coatings\ndepends not\nonly on the radiative properties of the coating but also on environmental\nvariables. In tropical environments, the cooling performance of RC\ncoatings deteriorates due to high humidity and high solar radiation.\nPrevious studies focused on developing high solar-reflective coatings\nto achieve subambient cooling in tropical environments. However, these\ncoatings have not demonstrated the ability to be used at a large scale,\nmainly due to their high cost or less durability. Herein, we test\nan RC paint coating composed of TiO<sub>2</sub> and polydimethylsiloxane\n(PDMS) in three different cities with high and moderate humidity levels.\nThough a significant reduction in the internal temperature of an RC\npaint-coated aluminum (Al) box is observed, compared to an uncoated\nAl box, in both high and moderate humidity environments, subambient\ncooling is not achieved. A comprehensive analysis is conducted to\nclarify the reasons behind the inability to attain subambient cooling.