Simulation case study of stack pressure impact on thermal load in high-rise buildings

Abstract

The reference building models in the EnergyPlus tool do not consider the stack effect. This is not an issue for small and low-rise buildings. However, this is significant in evaluating the heating and cooling load of high-rise buildings. This study evaluates and quantifies this stack effect in building energy simulation, EnergyPlus. The high-rise commercial building model in the EnergyPlus reference building set was used as a simulation test bed. The vertical multi-stories shaft zones were added inside the core zone in the existing building model. Then, the airflow network model was set in EnergyPlus so the internal airflow including the vertical and horizontal directions through the shaft zone as well as the core and perimeter zones were configured. The simulation model was calibrated against the actual pressure distribution between the core and perimeter zones in all floors of high-rise buildings from the literature. This model calibration was conducted manually by changing the discharge coefficient of the openings between thermal zones. The heating and cooling load of the proposed model were compared to the existing model which does not consider the vertical airflow through the shaft zones. The quantification with relative load mismatch was analyzed by floors and environment including the temperature difference between indoor and outdoor, and wind speed. Moreover, the impact of the air mixing and infiltration on the heating and cooling load was quantified. The result of this study reveals the significance of the stack effect in calculating the heating and cooling load.