Review of radiative cooling materials: Performance evaluation and design approaches

As the planet warms, keeping cool without releasing greenhouse gases will be a challenge, but radiative cooling technology is poised to meet this goal. Hundreds of radiative cooling materials have been reported in the literature to yield acceptable cooling performance, but there is a lack of guideline for engineers to select the suitable candidates for commercialization. In order to tackle this problem, we gathered information on 55 radiative cooling materials reported in the literature according to our selection criteria and grouped them into four categories: multilayer structure, metamaterial, randomly distributed particle structure, and porous structure. Using a comparison method that objectively evaluated their cooling performance and commercialization potential, we found that the polymer-based porous structure and randomly distributed particle structure without reflective metal layer tend to be more promising for commercialization because of their superior cooling performance, low cost, ease of manufacture, high scalability and compatibility. Furthermore, we proposed an approach for the design and optimization of potential radiative cooling materials. This review will not only provide engineers with guidelines for selecting the best materials in applying and commercializing this technology, but will also enable researchers to propel this technology forward through improved material design in the future.