Stack effect is the movement of air into and out of buildings, chimneys and flues and is driven by a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. Less dense hot air rises and is replaced by denser, cool air. The greater the thermal difference and the height of the structure, the greater the stack effect. The stack effect is also referred to as the "chimney effect" and it helps drive natural ventilation and infiltration.

stackeffect