Numerical modelling and experimental validation of multilayer daytime radiative coolers

Daytime radiative cooling (DRC) is an innovative concept of passive cooling that can achieve sub-ambient temperatures, even in the presence of intense sunlight. By integrating DRC as a finishing layer in building envelope systems, it becomes possible to take advantage of this phenomenon to increase the indoor comfort in hot seasons. In this study, we have developed a finite element model to analyze the behavior of a thermo-chromic material (TCM) when used as a finishing layer on a roof. The performance of this TCM is compared with that of a commercial water-proof paint. The roof layout consists of the finishing layer, a standard insulation material, and a concrete slab. It is worth noting that the concrete slab possesses high thermal energy storage capacity, which is often overlooked in the analysis of DRC systems. To obtain the radiative properties of the TCM layer, we have utilized experimental data. Subsequently, we evaluate the heat flux and thermal gradient experienced by the envelope system to assess the potential of TCM in reducing undesired heat loads. In order to comprehensively evaluate DRC in different climates, we consider weather variables for an entire year and for two distinct locations. By conducting this research, we aim to enhance our understanding of the capabilities and limitations of DRC systems. This knowledge will contribute to the development of more efficient and sustainable building designs, ultimately leading to improved energy management and reduced environmental impact.