Chinese paint cuts wall temperature by 25 degrees Celsius in summer test: report

Commenters discussed a Chinese radiative-cooling coating reported to cut wall surface temperatures by about 25°C on hot days and lower internal tank temperatures by roughly 7°C. Markoff relayed that developers claim the paint combines very high solar reflectance and infrared emissivity (up to 97%), uses a biomimetic microstructure to be thin (~100 µm), survived 180 days and 40,000 scrub tests in a Hainan petrochemical trial, and is now in mass production with stated annual capacity of 600,000 tonnes and an estimated 15-year lifetime. He emphasized the appeal: passive, no electricity or refrigerants, big water savings versus sprinkler cooling, and direct heat rejection through the 8-13 µm atmospheric transparency window.

Others pushed back. sbierwagen pointed out known limitations of passive daytime radiative cooling, arguing condensation risk and the seasonal problem that buildings in temperate climates often need to retain heat, so widespread use isn’t straightforward. Markoff himself expressed skepticism about whether this formulation is materially better than existing high-reflectance paints. The discussion therefore split between optimism about a scalable, durable radiative solution for extreme-heat applications and caution that real-world trade-offs, climate context, and comparative performance versus current coatings remain open questions.