Development of radiative cooling and its integration with buildings: A comprehensive review

Radiative cooling is an appealing heat exchange form based on thermal radiation from terrestrial objects to outer space, which can be potentially applied to numerous cooling applications for system performance improvement without energy input. Due to the poor solar reflective ability of previous cooling materials, radiative cooling technology has been largely limited to nocturnal cooling for several decades. Thanks to the recent successful development of highly efficient selective and broadband thermal emitters either backed with high solar reflective metal films or intrinsically equipped with excellent solar reflectance properties, the daytime radiative cooling has been practically fulfilled, which is arousing worldwide research interests. Notably, the emerging nanophotonics or metamaterials-based fabrication approaches are widely reported with the prominent ability to tailor spectral properties for sub-ambient cooling enhancement. Porous polymer-based scalable paints with micro-and nano-pores are also developed with substantial daytime cooling capacities by considerably backscattering sunlight and emitting thermal radiation. This work comprehensively reviews the latest progress on radiative cooling regarding its theoretical fundamentals, material designs and a variety of novel applications with a special focus on building-integrated cooling performance improvement. Considering the preceding extensive research on cool roofs with remarkable potential for real-world implementations, radiative roof cooling has been discussed in terms of cool roof-based heat transfer models, thermal and energy performance, and economic and environmental benefits. Lastly, research prospects of the radiative cooling technology are envisaged to provide insight for further investigation.