Optimizing window ventilation strategies for high-rise residential buildings with U-shaped lightwell: Simulating gaseous pollutant cross-room transmission

Abstract

The lightwell structure widely used in high-rise residential buildings becomes a pathway for the cross-room transmission of gaseous pollutants. In order to devise effective strategies for window ventilation, it is necessary to conduct research on the transmission characteristics of pollutants in the lightwell. The unsteady-state characteristic of the temperature in natural conditions is represented using a sine function. The transmission of pollutants in the lightwell during the 24 h was simulated by computational fluid dynamics (CFD) employing the RNG k-ε turbulence model and continuous phase model. Three pollution sources were considered at three typical building heights: low floor (5 floors), middle floor (18 floors), and high floor (32 floors). Moreover, the window ventilation time was accurately determined by calculating the room's re-entry ratio near the pollution sources. The results show that the day (24 h) can be divided into three time periods based on the airflow pattern in the lightwell: the downward airflow time (17:00 to 2:30), the upward airflow time (5:00 to 15:00), and the transition time (2:30 to 5:00 and 15:00 to 17:00). During the transition time, pollutant is transmitted both horizontally and vertically, and all rooms around the pollution source are unsuitable for window ventilation.