Water based inorganic radiative cooling paint with high thermal stability and excellent anti-aging ability

Passive daytime radiative cooling (PDRC) is recognized as a highly effective strategy for building thermal management. However, the practical application of current PDRC coatings is largely restricted by their predominant dependence on less durable organic materials. In this study, we developed an all-inorganic coating using silica sol, metakaolin (MK), and glass fiber powders (GF), abbreviated as the SMG coating. The fabricated SMG coating possesses a hierarchically porous structure, achieving a high solar reflectivity ( R _S ) of 91.61% and a strong infrared emissivity ( E _IR ) of 96.34%. Outdoor tests show that under the condition of an average internal temperature of 40.92 °C in summer, this coating can reduce the internal temperature by an average of 5.07 °C. The all-inorganic composition endows the coating with exceptional stability, enabling it to retain structural integrity and superior optical performance even after annealing at 1200 °C, ultraviolet (UV) exposure, and immersion in acidic, alkaline, and saline solutions. EnergyPlus simulations verify that the application of the SMG coating on building envelopes in hot-summer and cold-winter climatic zones yields significant annual energy savings. Owing to its straightforward fabrication process and excellent scalability, the SMG coating provides a cost-effective and durable solution for reducing energy consumption and carbon emissions in building envelopes.