Ventilation performance analysis on low-rise courtyard building for various courtyard shape factors and roof topology

Abstract

Residential buildings in the street canyon are highly suffering from reduced natural ventilation since the surrounding buildings completely mask the window and door openings. For such buildings, ventilation through the roof is an excellent method, and the buildings with courtyard space are believed to provide good ventilation and comfort. However, proper designing of courtyard buildings is highly essential, and for that, a complete airflow study in and around the courtyard building is required. Hence, in this research work, a low-rise residential courtyard building is considered, and the influence of courtyard space shape factor and roof topology on the ventilation performance of courtyard buildings is studied. The airflow study is made with the aid of the computational fluid dynamics (CFD) technique. Grid sensitivity analysis, validation of CFD results with wind tunnel experiments, and repeatability error analysis on wind tunnel test rig are also conducted to ensure the reliability of CFD simulation results. From this analysis, the courtyard with a wider space entraps more air from the atmosphere, and the building with low height offers uniform airflow in the courtyard space. Roof topology significantly influences the airflow around the building. Among the analyzed roof shape, pitched roof shape seems to perform relatively better and enhance the indoor air velocity by 42% with reference to the building without courtyard space. Also, the thermal comfort index for the building with courtyard space is 1.16 whereas for a building without a courtyard is 2.42 on a 3 scale. The percentage dissatisfaction index (PPD) is 52.9% lesser in the building with courtyard space.