Combination of Radiative and Evaporative Cooling in Porous Coating Gel to Achieve High-Performance Hybrid Passive Cooling for Buildings

Addressing rising cooling demands driven by global warming, this study presents a zero-energy passive cooling strategy by synergistically integrating radiative and evaporative mechanisms. We developed a porous coating gel, PCp, composed of PVDF-HFP/CSH/PVDF, featuring high solar reflectivity (93.63%), high infrared emissivity (92.85%), and excellent hygroscopic capacity (1.80 g/g). This design enables daytime multieffect cooling by combining solar reflection, radiative heat dissipation, and evaporative cooling, while simultaneously harvesting atmospheric moisture at night. Benefiting from this synergy, the PCp coating achieves a subambient temperature reduction of up to 7.1 °C under simulated sunlight. This work offers a novel and efficient material solution for low-energy thermal building thermal management.