A numerical investigation of balcony geometry impact on single-sided natural ventilation and thermal comfort

Balconies could enhance natural ventilation (NV) and reduce reliance on mechanical ventilation in cooling dominant climates. Indoor environment and thermal comfort under NV mode are usually less predictable than Mechanical Ventilation (MV), and balcony geometry's impacts on these parameters have not yet been classified. This study aims to investigate the effects of balcony depth and door opening scale on the NV performance and thermal comfort of the attached Livingroom. The present article conducted a 3D – steady-state Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent. The simulation results were validated against measured data in a residential high-rise building in subtropical Brisbane, Australia. Five different openings and nine depth scenarios are defined as configuration tests. The simulation results reveal that both the opening and depth sizes affected the Indoor Air Distribution (IAD), mean Indoor Air Velocity (IAV) and temperature, while these effects are not identical in the defined scenarios and opening size had more significant effects. The smaller openings, including the case study, led to a better thermal comfort than other scenarios. Contrary, the smaller depth sizes (less than 2 m) led to a non-uniform and unstable IAD at the attached Livingroom. The best thermal comfort and the highest IAV also occurred, respectively, in the deeper balconies with 35 and 30% depth ratio. Finally, a comparison between the findings and literature reveals the balcony's depth scale effects on mean IAV significantly depends on the orientation of buildings.