Analysis of the Impact of the Pressure Coefficient on the Simulation of Natural Ventilation in Indoor Environments

Abstract

For predominantly hot climates, ventilation plays a fundamental role in thermal comfort by removing the thermal load from the environments and assisting in the user's thermal exchange processes. However, natural ventilation processes are not elementary, demanding complex modeling for estimating and verifying thermal comfort requirements. The objective of this work is to compare different estimates of wind pressure coefficient for a building: estimated by EnergyPlus and by CFD simulation, as well as the respective impacts on the renewal of ambient air. An educational building located in Palmas, TO, with complex geometry and natural ventilation solutions was studied. To the air renewal rates obtained with the pressure coefficients calculated by EnergyPlus and the null coefficients, the average deviation performance indicator (MBD) was applied to evaluate the under or overestimation in relation to the air renewal rates resulting from the simulation with the pressure coefficients obtained by CFD. The results show that although the behavior of the air change curves is similar with the CFD and EnergyPlus pressure coefficients, the results obtained with EnergyPlus tend to underestimate the air change rates. It is not recommended for buildings with non-rectangular and/or complex geometry to use EnergyPlus to calculate pressure coefficients and the use of null coefficients. It is recommended to obtain the pressure coefficients through simulations with a CFD.