Indoor air quality performance of ventilation systems in classrooms

This study aims to evaluate the field performance and the efficiency of ventilation systems in school buildings. Three classrooms installed with ventilation systems in a high school in Seoul were selected as a test bed for this study. The ventilation systems consisted of two types of multi air-conditioning ventilation system and a window type air-conditioning ventilation system. The ventilation performance was measured by the blower door and tracer gas methods as follows: (1) Evaluation of air tightness and air infiltration in the classrooms; (2) Indoor ventilation performance based on the operating condition of ventilation systems; (3) Ventilation performance based on the operating conditions of ventilation systems and air-conditioners; and (4) Local ventilation efficiency and performance based on the operating status of the ventilation systems and air-conditioners. As a result, the ventilation efficiency was measured at 34.8%-97.8% for the duct type of ventilation and 82.6% for the window type ventilation. In this study, classroom characteristics such as high air infiltration low air tightness lowered the ventilation effectiveness. The ventilation efficiency varied based on the location of air inlet and outlet ducts and the existence of furniture. However, local ventilation efficiency was not significantly affected according to the results of this study. The results showed that a ventilation rate of 1000 cubic meters per hour (CMH) or more would be required to maintain 1000 ppm of CO ₂ concentrations as per IAQ criteria for Korean classrooms.