The potential of balconies to induce wind-driven natural ventilation in single-sided ventilated high-rise apartments

Single-sided ventilation is known to be less effective than cross ventilation; however, it is still commonly used in high-rise apartment buildings because of various factors, such as unit optimization and land constraints. Its limitations and widespread use mean that there is a need to improve its natural ventilation performance with appropriate façade relief to avoid poor indoor air quality and to reduce energy consumption.A balcony is an architectural element which has various benefits. Among these, in a single-sided ventilated high-rise apartment building the provision of balconies can improve the natural ventilation performance of the apartments. A better understanding of the potential of balconies to induce natural ventilation can contribute to the optimization of single-sided ventilation performance in single-sided ventilated (SSV) high-rise apartment buildings. This study aims to investigate the improved ventilation potential of balconies and to generate recommendations for achieving this.This study adopts Computational Fluid Dynamics (CFD) as the primary tool. CFD is an attractive application tool for investigating outdoor and indoor airflows for buildings due to its flexibility, cost effectiveness, accuracy and ability to provide comprehensive data. However, CFD comes with two main drawbacks: it involves a large amount of computation and its results are often difficult to assess. Since there is a lack of research on CFD simulation for tall buildings, it is the aim of this study to identify an effective, reliable and simple method to investigate the impacts of balconies on wind driven ventilation performance for high-rise apartment buildings using CFD. As its predictions can be uncertain, validation studies are completed in this study using existing experimental data and empirical models. This study demonstrates that the provision of balconies on the façades of SVV apartment buildings can significantly improve the natural ventilation performance of the buildings; however, if inappropriately designed, balconies can reduce ventilation performance. A set of recommendations for practical application of a balcony is presented in this study. It has also been found that coupled CFD simulation is an appropriate approach to predicting the ventilation performance of tall buildings. Important aspects of the CFD simulation process and its limitations are also outlined