By Md. Safiuddin, Navid Esmaeli, Nicholas Dunne, Jacqueline Horne, Merve Erenler, Nirmala Singh, Sebastian Kleefisch, Baryalai Sharifi

EXECUTIVE SUMMARY

This study examined the transmission risk of COVID-19 in indoor spaces and how the modifications of certain building parameters can reduce that risk. It is the duty of responsible members of the construction industry to not only be aware of public health issues but also to explore and examine how built spaces can be reformed to be safer. As individuals return to their pre-pandemic routines, it is crucial to understand the building parameters of interior spaces that affect the transmission of COVID-19, and to create guidelines to protect the occupants of buildings.

The primary research for this project was conducted through an analytical study for modeling a classroom (CLE-326) at the Casa Loma Campus of George Brown College. Assessment tools were developed based on the findings of secondary research, i.e., literature review pertaining to the major building parameters and their effects on the transmission of COVID-19 in indoor spaces. The research was performed by studying the effects of the key building parameters on indoor airflow trajectory and velocity, deposited mass concentration on desk and table surfaces as well as door push bars, suspended mass concentration of air at mouth level, relative proportions of the particles of different sizes in deposited and suspended masses, local mean age and turbulence intensity of air, local air quality index at mouth level, and mass deposition rate of the particles of various sizes.

In total, twenty-four models were developed for the selected classroom using SolidWorks. Twelve models were developed for the winter season and the other twelve models for the summer season. The key variables used in developing the models were relative humidity of indoor air, room temperature, air change rate, occupant density, and surface finish. The indoor temperature and relative humidity were varied in summer and winter seasons. The room temperature and relative humidity chosen for the winter models were 22°C and 40%, respectively. On the other hand, for the summer models, the room temperature and relative humidity were 24°C and 50%, respectively. For both seasons, the air change rates of 2, 4, 6 were used in the development of models. The occupant density was also varied – twelve models were developed considering the full capacity of the classroom, which is intended for 60 students, using 1.85 m2 floor area per student. The other twelve models were developed for 30 students, considering 3.7 m2 floor area per student. In addition, the half of the models were developed taking all surfaces into account as smooth. The remaining half of the models were developed by considering the high-contact areas, such as the desk, table, and door push bar surfaces as rough.

The classroom models were simulated to observe indoor airflow trajectory and velocity, suspended mass concentration of the room air, and the deposited mass concentrations on desk and table surfaces as well as door push bars that frequently become in contact with students and their professor. In addition, local mean age of indoor air, average indoor air temperature, average relative humidity of air in the classroom, turbulence intensity of air, and local air quality index were derived from the simulation of different classroom models. The relative amounts of the particles within the deposited and suspended masses in respect of various sizes were also determined from the models, with a focus on 2.5 μm, 5 μm, and 10 μm sizes. Furthermore, the mass deposition rates of the particles of these three sizes were determined. The above model results were obtained for the summer and winter seasons. In both seasons, the selected key building parameters exhibited significant impacts on the model outputs, except for surface finish, which has shown marginal effect. However, more impacts were noticed in the case of winter models due to lower temperature and relative humidity. Besides, the greatest effect was observed for air change rate, followed by occupant density in the classroom. The overall findings of the study were used to formulate the health and safety guidelines for indoor spaces.

Investigation of the Parameters of Indoor Spaces in Controlling the Transmission of COVID-19, 5.0 out of 5 based on 1 rating