From materials design to real-world performance in passive radiative cooling paints

Abstract

Global warming arises from the net accumulation of solar energy within the Earth–atmosphere system. Passive radiative cooling paints (PRCPs) offer a scalable approach to mitigate this imbalance by reflecting solar radiation and emitting heat to outer space, thereby reducing surface and urban temperatures. PRCPs are photonic composites, in which binders, fillers and interfaces govern scattering, absorption and mid-infrared emission. Most existing studies treat binders and fillers as independent, idealised phases—an assumption that fails to capture the complexity of practical PRCP systems. In reality, filler–filler and binder–filler coupling as well as coating morphology collectively govern cooling performance in ways that single-component models cannot predict. External factors, e.g. building configuration, sky view factor and atmospheric conditions, further influence performance, yet are rarely integrated into material-level analyses. This review bridges this gap by examining, for the first time in a unified framework, how intrinsic material properties, interfacial interactions and composite architectures, together with climatic constraints and building-to-urban deployment contexts, jointly determine cooling performance. We further highlight emerging multifunctional directions, i.e. weathering resistance, flame retardancy, thermal adaptivity and sustainable formulations. Finally, we identify unresolved challenges and outline priority directions to advance PRCPs towards real-world application.