Solar-Adaptive Cooling\nBlocks Composed of Recycled\nFabric

Radiative cooling technologies have had a significant\nimpact on\nadvancing carbon neutrality efforts by significantly improving the\npassive cooling efficiency. The tandem of conduction and radiation\nenables solar-adaptive radiative cooling through the insulating effect\nof materials along with solar absorption, which affects the thermal\nstate of materials and enhances radiative thermal transfer from the\nsurface under solar irradiation. This enhancement is achieved by utilizing\nthe porous polymeric structure of materials, which facilitates improved\nconduction pathways along with solar reflectance, while maintaining\nthe effective emission of thermal radiation. In this particular scenario,\nblocks, which were made of recycled fibers, offer a great opportunity\nas solar-adaptive cooling materials, enabling their easy deployment\nfor cooling applications. Herein, we have fabricated a porous block\nusing fiber wastes that combines strong solar reflectance (92%) at\nthe 1 μm region and high thermal infrared emittance (∼75%)\nat the 10 μm region. The combination of effective solar reflection\nand thermal infrared emission allows the fiber block to achieve a\nhigh cooling performance of approximately 68 W/m<sup>2</sup> under\nsolar irradiation. In addition, the fiber block works effectively\nfor insulation during the night, thereby enhancing its heat retention\ncapabilities. The economic and environmental advantages of the fiber\nblock make it a cost-competitive and sustainable choice for near-market\ncooling technologies. This design is anticipated to expand the practical\napplication range of passive cooling.