Analysis of Building Retrofit, Ventilation, and Filtration Measures for Indoor Air Quality in a Real School Context: A Case Study in Korea

Abstract

While many school retrofits in Korea tend to focus on energy savings, some school operation practices and policies in the field may cause indoor air quality issues. This study aims to analyze the indoor air quality impact when selected measures of the energy retrofit package are applied to classrooms in a real operation context with actual airflow and contaminant transport characteristics. The selected measures included replacement of envelope windows/doors/hallway-side windows, more airtight enclosures as a byproduct of adding envelope insulation, ventilation systems and air purifiers under various operating conditions, and natural ventilation. Actual classrooms with the ages of 10, 20, and 80 years were selected. Their CONTAM base models were calibrated with the measured airflow and contaminant transport variables per American Society for Testing and Materials (ASTM) D5157. The near-open-air hallways and frequent door opening made ambient PM2.5 in the hallways, which initially originated from outdoors, flow into the classrooms. Therefore, the infiltrations and penetrations from hallways to classrooms should also be secured along with those via the envelope. When the enclosures’ airtightness is enhanced, mechanical ventilation and filtration should be in operation. Specifically, they should operate independently from school energy demand reduction policy. Installing a high-efficiency filter can help a situation when mechanical ventilation needs to run at a reduced volume. Natural ventilation, as intended for energy savings, should be introduced only when the outdoor conditions are desirable and should be supplemented with a high-capacity air purifier to maintain stable indoor concentrations.