Buoyancy-driven natural ventilation: The role of thermal stratification and its impact on model accuracy

Since the invention of mechanical ventilation systems, natural has been deemed inferior compared to active systems for buildings. The recent COVID-19 pandemic and raising awareness climate change issues have rekindled interests in as a sustainable method pollutant removal. Modelling is challenging due uncontrollable outdoor conditions. Simple models such well-mixed air model assume uniform indoor temperature. However, thermal stratification can induce significant temperature differences vertical direction, thereby violating assumption. This study evaluates performance model, two-layer computational fluid dynamics (CFD) predicting under buoyancy-driven displacement ventilation. Compared experimental measurements, significantly overpredicts without since it assumes upper layer underpredicts lower CFD capture trend gradual increase with height. underpredict temperature, possibly errors introduced by assumption adiabatic surfaces. simplified cannot resolve stratification, high-fidelity models, should be used Experimental studies include measurements well temperatures or heat fluxes on surfaces so results develop evaluate numerical models.