Thermal Modeling of a Building Integrated Radiative Cooler for Space Cooling Applications

Recent developments of plasmonic emitters that emit infra-red radiation in the range of 8–13 micron wavelengths that can be transmitted through the atmosphere have opened up the potential of cooling buildings passively by radiating heat through this atmospheric window into the deep space. This paper presents an analysis of the potential of this method to cool buildings radiatively 24 hours per day. Air conditioning units consume a large amount of electricity and are the main drivers of peak electricity loads. A transient thermal model of a building integrated radiative cooling (BIRC) system was carried out for passive radiative cooling of buildings. A MATLAB code was developed for solving the heat transfer model of the BIRC system using a numerical iterative approach. The effects of operating parameters such as cooling emissive power and ambient conditions on the performance of the system were studied. Furthermore, effects of non-radiative heat transfer processes were studied by considering different heat transfer coefficients. Based on this analysis, energy savings potential of radiative cooling of buildings was estimated for the climatic conditions of Miami, FL, and Chicago, IL, USA for a fraction of a roof surface covered with a radiative cooler. Further, the results of this analysis are in line with previous studies estimating the cooling potential of up to 100 W/m² with radiative cooling systems. These results will help in estimating the economic value of cooling buildings by using plasmonic emitting surfaces on the building skins.