Optimizing indoor air quality and noise levels in old school classrooms with air purifiers and HRV: A CONTAM simulation study

Abstract

Efforts at the national level are being made to improve the indoor air quality of school classrooms. Air purifiers and heat recovery ventilation (HRV) are commonly used to achieve this objective. However, the noise generated by these systems often disrupts classes, leading students to be hesitant in utilizing them. This study proposes an operating method to minimize noise while improving indoor air quality through CONTAM simulations. The method involves operating the HRV in low wind mode during class time and strong wind mode during break time. The dissatisfaction rate (measured by the duration in which the CO2 concentration exceeded 1500 PPM) was minimal, with a rate as low as 0.2% over one year of occupancy. In the case of fine dust PM2.5, operating the air purifier 1 h earlier than occupancy time, while maintaining the existing HRV operation, resulted in a low dissatisfaction rate (PM2.5 concentration exceeded 15 μg/m3 during occupancy time for one year) of 2.6%. According to student reports, the use of weak wind mode during class and strong wind mode during break time resulted in reduced annoyance from the equipment noise. They expressed overall contentment with the experimental noise level, as long as the indoor air quality was improved. The study findings provide an effective and feasible approach to satisfying both noise and indoor air quality requirements. Furthermore, the methodology adopted in this study can be valuable for developing appropriate air purifier facility capacities in different schools.