Bridging the critical gaps of radiative sky cooling: From lab to applications

Radiative sky cooling offers a promising passive solution to rising energy demand and climate challenges. Despite significant progress in material innovation and laboratory demonstrations, a considerable gap remains between experimental research and practical application. In this review, the key challenges and recent progress in the field are examined, with a focus on how laboratory research can effectively serve real-world needs. The historical development and milestones that have gradually matured radiative sky cooling technology are first recounted, thereby setting the stage for its implementation across various applications. Subsequently, the fundamental performance characterization of radiative sky cooling materials is analyzed by discussing both routine laboratory tests and the expanded metrics required to address the complexities encountered in practical scenarios; this analysis reveals notable discrepancies between controlled measurements and anticipated performance. Additionally, testing methodologies for critical parameters are evaluated to address their theoretical foundations, current experimental limitations, and potential avenues for improvement. Finally, the review underscores the imperative transition from simplified laboratory assessments to the integration of radiative sky cooling materials into full-scale application systems. These insights aim to guide the development of robust, energy-efficient cooling systems for global deployment.