Radiative cooling applications toward enhanced energy efficiency: System designs, achievements, and perspectives

Radiative cooling utilizes the ultracold (∼3 K) deep space to cool terrestrial objects at no cost to active energy consumption. It finds widespread applications across various fields and paves a promising strategy for tackling global energy and environmental issues, such as scorching and freshwater shortages. However, a comprehensive review of the applications, efficacy, and future of radiative cooling technologies has not been reported. This review takes a retrospective view and summarizes the emerging radiative cooling applications for enhanced energy efficiency in various fields, encompassing building cooling, personal thermal management, solar cell cooling, thermoelectric power generation, freshwater collection, food production and storage, and other miscellaneous fields. The design novelties, achievements, and energy-saving capabilities are analyzed and discussed for each application field. By analyzing the cutting-edge research processes, we also extract the advantages and limitations of the present radiative cooling applications. Additionally, we summarize the up-to-date designs and performance achieved via radiative cooling implementations in various fields. Finally, we highlight the challenges and opportunities of extending radiative cooling technologies to multitudinous scenarios. The comparative and conclusive results in this work clarify the application progress and development direction of radiative cooling, promoting prototype designs and real-world implementations of radiative cooling-driven technologies.