Scalable-Designed Photonic Metamaterial for Color-Regulating Passive Daytime Radiative Cooling

Methods allowing passive daytime radiative cooling (PDRC) to be carried out in an energy-efficient and scalable way are potentially important for various disciplines. Here, we report a sustainable strategy for scalable-designed and color-regulating PDRC coating based on high-crystallinity photonic metamaterial (crystallinity: 71.5%; enhanced assembly efficiency: 72%), that is derived from the as-prepared 55 wt% solid content poly(methyl methacrylate-butyl acrylate-methacrylic acid) P(MMA-BA-MAA) monodispersed latexes (approaching theoretical limit: 59 wt%). Robust meter-scale PDRC coatings are constructed by various industrial modes onto diverse surfaces, addressing bottlenecks like dull appearance, high cost, low efficiency, and hard construction. Notably, the solar reflectance, long-wave infrared emittance, and calculated theoretical cooling power of the designed PDRC coating, respectively, reach ~ 0.94, ~ 0.97, and ~ 95.5 W m^-2 under solar radiation, which can achieve an average 5.3 °C sub-ambient daytime temperature drop in the summer in Nanjing. The cooling performance, scale preparation, and cost-effectiveness of the PDRC coating have extended into leading position compared with those of state-of-the-art designs. This work provides promising route to reduce carbon emissions and energy consumption for global sustainability.