Experiencing Passive Daytime Radiative Cooling in Commercial Roofs with Ultrahigh-Temperature Reduction Using Micro/Nanoparticles-Distributed Porous Polymeric Structure

Recently, great interest is pursued by researchers in radiative cooling paints (RCPs) due to enhanced passive cooling capability, space cooling demands are reduced, and greenhouse gas emissions are combated owing to hassle-free applicability on existing structures. In this study, different formulation of RCPs is developed such as RCP1, RCP2, RCP3, and RCP4. The real-time cooling capability of all the developed RCPs are experimentally investigated by painting a single layer on asbestos cement sheet and clay tile in indoor and outdoor conditions. Strategic selection of fillers and binders in the development of RCPs maximizes the reflection in solar window and emission in thermal window. During outdoor analysis at a tropical savanna condition, a drastic reduction in temperature of 12.36 °C is observed in RCP3 in a midday and sub-ambient cooling of −3.68 °C observed in nighttime. When compared to commercial white-paint-coated roofs, an excellent reduction of ≈4.3 °C is found with RCP3. Also, RCPs used in this study saves almost 335 Wm⁻² of energy on air conditioners by offsetting negative cooling power of commercial roofs (−300 Wm⁻²) to positive cooling power by 35 Wm⁻². Hence, this passive cooling technique saves people from deadly heat waves.