Numerical simulation of combined solar passive heating and radiative cooling for a building

Abstract

While solar energy can be utilized for passive space heating, efficient passive space cooling is achievable through lower temperature ambient thermal sources. In this study, a model was proposed for the combined solar heating and radiative cooling and a MATLAB code is developed to simulate combined space heating and cooling of a small building in Louisville, Kentucky. The combined system consists of the glazing/transparent insulation subsystem and the thermal storage subsystem. The space is passively heated and cooled by means of natural convection from the surfaces of the storage subsystem where the storage tank is heated by solar radiation and cooled by night sky radiation as a low temperature thermal source. The model for this system consists of several transient energy balance equations based on the lumped capacitance approach and it has been implemented utilizing MATLAB. Using the aforementioned system and the auxiliary heating/cooling units, the room temperature can be kept within the prescribed comfort range. The simulation is carried out to find the monthly and annual solar fraction, required heating demand, auxiliary heating demand as well as the unwanted heat gain during heating months. Also, the radiative cooling fraction, required cooling demand and auxiliary cooling demand during cooling months are obtained. The optimum value for transparent layer absorptivity was found to avoid unwanted heat gain. Parametric sensitivity was evaluated for material and design features related to the combined system. Simulation results for temperature profiles of the room and storage tank are also illustrated.