Stack pressure and airflow movement in high and medium rise buildings

This paper presents the result of a numerical simulation of the stack pressure in high and medium rise buildings under cold weather condition. The result shows that there is a movement of air from the bottom to the top of the building and escapes at the top either through open windows, ventilation openings, or other forms of leakage. The rising warm air reduces the pressure in the base of the building, drawing cold air in through either open doors, windows, or other openings and leakage. This stack effect occurs mainly in the core of the building such as stairway and elevator shaft and causes problems with energy loss caused by the airflow, the blocked elevator doors and discomfort due to inflowing of strong outdoor air. The simulation has been carried out for the high rise building in cold climate of Korea, considering three levels of air-tightness of the exterior wall of the building (tight, average and loose), and found to be the major reason of the airflow movement in the building. The effect of the wind speed velocity and direction on the movement of the airflow in the building has been also investigated under extreme cold condition for middle rise building located in China (7 floors) and the result shows that at high wind speed velocity this effect is very significant.