Improving the Effectiveness of Stack Ventilation by Supplying an Outdoor Air Stream

Abstract

Stack ventilation is the most common ventilation in public utility buildings and residential homes. Its task is to remove contaminated air from the room and thus maintain good indoor air quality. The aim of the study was to determine the effectiveness of the natural ventilation of one classroom and determine the impact of the additional air supply to the room on the stack ventilation effectiveness. The effectiveness of stack ventilation was tested in a classroom during winter months. The improvement of the effectiveness of stack ventilation was analyzed as a function of the number of open windows. An increase of 80% was obtained in the effectiveness of stack ventilation, when one window is opened. Lower increments were obtained when the number of windows opened were 2 or more. The maximum air change per hour during the tests was only 0.73 h-1. Despite of the influence of outdoor conditions on stack ventilation, the maximum air change per hour was lower than the recommended number of exchanges in classrooms. As a result, recommended ventilation rates in school classes were not achieved when using stack ventilation.