Abstract
(1) Background: Many schools and higher education settings have confronted the issue of reopening their facilities after the COVID-19 pandemic. In response, several airflow strategies spanning from adding portable air purifiers to major mechanical overhauls have been suggested to equip classrooms with what is necessary to provide a safe and reliable environment. Yet, there are many unknowns about specific contributions of the building system and its design and performance on indoor air quality (IAQ) improvements. (2) Methods: this study examined the combined effect of ventilation type, airflow rates, and filtration on IAQ in five different classrooms. Experiments were conducted by releasing inert surrogate particles into the classrooms and measuring the concentrations in various locations of the room. (3) Results: we showed that while the distribution of particles in the space is a complex function of space geometry and air distribution configurations, the average decay rate of contaminants is proportional to the number of air changes per hour in the room. (4) Conclusions: rooms with a central HVAC system responded quicker to an internal source of contamination than rooms with only fan coil units. Furthermore, increasing the ventilation rate without improved filtration is an inefficient use of energy.
Highlights
Heating, ventilation, and air conditioning (HVAC) systems are essential elements of modern buildings
While the primary function of HVAC systems is to provide a more comfortable thermal environment, the design and efficiency of ventilation systems play a significant role in the indoor air quality of buildings through reductions in aerosol and CO2 concentrations
Ventilation system design can be used as an engineering control method to decrease indoor particle concentration and decrease disease transmission risk [2]
Summary
Ventilation, and air conditioning (HVAC) systems are essential elements of modern buildings. While the primary function of HVAC systems is to provide a more comfortable thermal environment, the design and efficiency of ventilation systems play a significant role in the indoor air quality of buildings through reductions in aerosol and CO2 concentrations. Ventilation systems exchange potentially contaminated indoor air with clean air. This dilutes or removes pathogen-containing aerosols, reducing the inhaled dose to occupants [1]. Ventilation system design can be used as an engineering control method to decrease indoor particle concentration and decrease disease transmission risk [2]. Buildings with a low air exchange rate, inefficient ventilation design, or a high occupant density have a much higher possibility for airborne infection. Indoor contamination has been reported to reside in ducts [3,4], diffusers [5], and filter media [6,7]
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