Analysis and modeling of building thermal response to investigate the effect of boundary conditions

Thermal load simulation and sensitivity analysis are performed for a building in Tehran by numerical means. Heat conduction equation of the walls together with appropriate convection and radiation boundary conditions is simulated numerically to compute temperature distributions in the walls. This research proposes a heat balance method coupled with a bulk model to calculate the building thermal load. In the first step, the results of the building thermal load for weather data of Tehran are compared and validated with those of Carrier HAP software, and a good agreement is found between them. The building thermal load depends on boundary conditions of the building. The influence of the boundary conditions such as emissivity of interior and exterior surfaces of the walls and convective coefficients on the building thermal load is investigated through the application of a sensitivity analysis. Then sensitivity coefficients, which demonstrate the significant and impact of internal and external boundary conditions of the walls on the building thermal load, are calculated numerically using a finite-difference method. The results showthat internal radiation is an important component of the building energy balance.