Optimisation of room vent configuration for solar chimney-induced indoor environment in high-rise residential buildings

• Lower-middle supply vent and higher-middle exhaust vent result in smallest MAA. • Aspect ratio and orientation of supply vent has little effect on flow rate and MAA. • A 10-storey solar chimney generates 49.8 times minimum required ventilation. • Solar chimneys can provide good thermal comfort in tropical climates. Solar chimneys (SCs) have been widely investigated as passive devices for enhancing buoyancy-driven ventilation in buildings. However, many previous studies evaluated the airflow performance of isolated chimney systems without considering the interaction between the chimney and indoor spaces. Consequently, the influence of room-side vent configurations on indoor air quality (IAQ) and thermal comfort remains insufficiently understood, particularly in high-rise residential buildings. This study addresses these gaps by numerically examining how different vent designs affect SC-driven ventilation. A parametric analysis was first conducted at the room level to optimise the configuration of supply and exhaust vents. The results show that the vertical placement of the vents plays an important role in determining the mean age of air (MAA) within the breathing zone, although its effect on the overall airflow rate is relatively small. In comparison, the opening size of the supply vent significantly influences both ventilation rate and breathing-zone MAA. The relative orientation between supply and exhaust vents was found to have only a minor influence on the ventilation performance. Based on the optimised vent configuration, a case study of a ten-storey residential building equipped with solar chimneys was subsequently analysed. Under a solar irradiance of 600 W·m⁻2, the system produces an average ventilation rate of approximately 1544 L·s⁻1 per storey, which is nearly fifty times higher than the minimum requirement specified in ASHRAE Standard 62.2. In frequently occupied indoor areas, the predicted air velocity reaches about 0.51 m·s⁻1, exceeding the 0.31 m·s⁻1 threshold required for acceptable thermal comfort in Singapore’s daytime climate based on the extended predicted mean vote (ePMV) model.