PSHFHP as a building roof and its characterizations. (A) Schematic illustration of the PSHF_HP as a radiative cooling roof, showing the synergetic effect of sunlight scattering, infrared thermal emittance and heat isolation features. (B), (C) Photograph of the synthesized PSHF_HP on a glass surface with a size of ~20 cm × 20 cm and its CIE chromaticity coordinates. (D), (E) Typical SEM micrograph of PSHF_HP with different magnifications. Inset: pore size distributions of PSHF_HP, showing abundant randomly distributed micropores and nanopores. (F) Spectral reflectance of PSHF_HP between 0.3 and 16 μm. The normalized ASTM G173 global solar spectrum is shaded as yellow region; inset: schematic diagram showing the film structure with hierarchical nano/microscale pores is conducive to enhancing the total scattering efficiency by multiple diffuse reflections at various angles.