Analysis of vertical movement of particulate matter due to the stack effect in high-rise buildings

Outdoor particulate matters (PM) enter the indoors with airflow due to wind pressure, temperature differences, and variable pressures from HVAC systems. PM introduced into the indoor space is deposited on the surface according to the indoor environmental conditions to reduce the indoor particle concentration. In particular, in high-rise buildings in winter, the stack-induced driving force, which is a function of the height of the building and the temperature difference between indoor and outdoor, is dominant. High-rise buildings have vertical pathways for the transport of PM between floors within the building, and eventually distribute it to households. This study aims to analyze the characteristics of PM transport in the vertical shaft in a high-rise building, and to propose a method to calculate penetration and deposition properties to predict indoor particle concentration. An optimization method was proposed to calibrate the multi-zone airflow and particle transport model using field measurement, multi-zone airflow/contaminant simulation, and genetic algorithm (GA)-based optimization techniques. The target building was a 43-story high-rise residential building, and CONTAM was used for multi zone simulation. The results showed that the PM concentration in the vertical shaft decreased toward the upper floors due to wall deposition. The deposition rate in the vertical shaft was calculated to be less than 0.3 h-1, was the smallest at the Neutral Plane Level (NPL), and increased toward the upper and lower floors. In other words, the deposition rate in vertical space was inversely proportional to the airflow rate. The deposition rate of the vertical shaft was calculated to be smaller than that of the horizontal space. The reliability of the PM concentration prediction results calculated using the proposed method in this study was valid, and satisfied ASTM D5157.