Enhancement and Homogenization of Indoor Air Quality in a Classroom Using a Vertical Airflow Ventilation Scheme

Abstract

Since air quality has a great influence on students’ health and learning ability, enhancing air quality in classrooms is important. Currently, widely distributed ventilation systems operate by moving airflow horizontally from ventilation inlets and outlets on the ceiling. This method can reduce the average pollution in a space by diluting it through air exchange; however, it is limited regarding homogeneous cleanliness due to air stagnation at some locations. Therefore, in this study, a new ventilation system was devised to improve indoor air quality and spatial homogeneity by installing ventilation inlets on the ceiling and numerous outlets on the floor, creating a vertical airflow in the interior space; this system was then applied to a middle school classroom. Using the age of air as an index, air quality improvement between the existing and newly designed ventilation systems was compared. In the classroom with the existing ventilation system, the age of air was low in the area near the ventilation inlets, while air congestion areas were widely distributed and air age was high near the outlets. Conversely, in the vertical airflow classroom, the average age of air was approximately 15% lower than that with the existing ventilation system, and the deviation of air age for each position in the classroom space was also reduced, showing a uniform air age distribution. Therefore, the vertical airflow ventilation system proposed in this study can be an effective ventilation scheme for enhancing and homogenizing indoor air quality.

Comparison of Local Mean Age of Air between Displacement Ventilation System and Mixing Ventilation System in Office Heating Conditions during Winter

“…Hence, simulation methods for the MVS are well established in many previous studies. Accordingly, the MVS cases listed in Table 1 were analyzed by referencing the analysis techniques of preceding studies [42,46]. 10a,c, where DVS or Improved DVS was applied, a relatively uniform temperature distribution ranging from 20 to 24 °C was observed from the floor to the ceiling across the entire office space, except for the area surrounding the APs used as VO; this can also be corroborated by the results in Figure 8.…”

“…Hence, simulation methods for the MVS are well established in many previous studies. Accordingly, the MVS cases listed in Table 1 were analyzed by referencing the analysis techniques of preceding studies [42,46].…”

Effect of air sterilizers in an outpatient clinic at a tertiary university hospital

“…However, when the Middle East Respiratory Syndrome (MERS) spread, infection within buildings through HVAC systems was confirmed ( 9 ). Therefore, the authors considered ways to reduce the risk of infection to other people by inactivating the virus before it is inhaled into the HVAC system ( 2 , 3 ). We installed a recently developed air sterilizer…”

Effect of air sterilizers in an outpatient clinic at a tertiary university hospital

“…Therefore, heating, ventilation, and air conditioning (HVAC) systems are beginning to be studied more deeply to help eliminate airborne viruses, fungi, and bacteria. [1][2][3]7,8 1-8 When natural ventilation is not possible, mechanical ventilation and the use of an air puri er are recommended. 1,3,8 Therefore, we attempted to con rm whether mechanical ventilation could diminish the presence of airborne toxins by installing a recently developed air sterilizer in a newly remodeled outpatient clinic at a tertiary university hospital.…”

“…After the COVID-19 outbreak, interest in airborne virus infections has increased. [1][2][3][4][5][6][7][8] Natural ventilation is di cult in hospitals due to patient overcrowding, and mechanical sources have been applied to assist in ventilation [1][2][3][4][5][6][7][8] . Therefore, heating, ventilation, and air conditioning (HVAC) systems are beginning to be studied more deeply to help eliminate airborne viruses, fungi, and bacteria.…”