Scaled experimental and numerical studies of the influence of heat flux on the stack ventilation characteristics of a multi-shaft building

Natural ventilation is a sustainable way to improve indoor air environment and reduce building energy consumption as well as carbon emission. The deep-plan building, which has a high ratio of internal floor area to external wall area, cannot be effectively ventilated naturally. In this study, multiple shafts are applied in deep-plan buildings to enhance the effectiveness of stack ventilation. The experimental and numerical results confirm the advantages of multi-shaft by comparing with single-shaft building. The temperature variation within 75% of the indoor space is approximately 1 °C, while the mean ages of air are reduced by 70.78%, 69.80%, 68.77%, 59.91%, and 51.56%. When the heat flux on all storeys increases, it has greatest influence on the buoyant ventilation on first storey, while has least influence on top storey. The maximum difference between ventilation rates on first storey and fifth storey increases to 23.35% when the heat flux is 90 W / m 2 . More importantly, it is found that increasing the heat flux on a specific storey (except the top storey) has a positive correlation with the ventilation rates through the remaining storeys. However, an increase in the heat flux on the top storey has a negative correlation with the stack ventilation through the other four storeys. When the heat flux on the top storey is increased from 10 to 90 W / m 2 , the ventilation rates on other storeys are reduced by 3.64%, 3.34%, 2.65% and 1.61% compared with that for the reference heat flux of 50 W / m 2 , respectively. The findings from the current study are independent of the number of storeys and ventilation shafts in the buildings. Hence, they are valuable for designing a naturally ventilated building.