Passive cooling paint enabled by rational design of thermal-optical and mass transfer properties
Jipeng Fei, Xuan Zhang, Di Han, Lei Yue, Fei Xie, Kai Zhou, See Wee Koh, Junyu Ge, Hao Zhou, Xingli Wang, Xinghui Wu, Jun-Yan Tan, Yuheng Gu, Yongping Long, Zhi Hui Koh, Su Wang, Panwei Du, Tangwei Mi, Bing Feng Ng, Lili Cai, Chi Feng, Qiaoqiang Gan, Hong Li
Abstract
Integrating radiative and evaporative cooling shows promise for enhancing passive cooling, but durable self-curing integrated cooling paints remain underdeveloped. We designed a modified cementitious structure with advanced thermal-optical and mass transfer properties, boosting cooling power while ensuring durability, mechanical strength, and broad adhesion. The paint achieves 88 to 92% solar reflectance (depending on wetting), 95% atmospheric window emittance, ~30% water retention, and self-replenishing properties, maintaining stable optical performance even when wet. Field tests in tropical Singapore demonstrated superior cooling performance compared with commercial white paints. Pilot-scale demonstrations highlighted consistent electricity savings under varying weather conditions, supported by theoretical modeling. By leveraging sustainable water evaporation and thermal radiation, this paint offers a practical and long-term solution for mitigating the urban heat island effect.