Numerical investigation of CO2 distribution in naturally ventilated classrooms

This thesis is aimed at examining the indoor air quality of a classroom in the Mechanical Engineering building of Karadeniz Technical University with solutions made for different scenarios using the computational fluid dynamics (CFD) method. ANSYS Fluent 2022 R2 software was used for the numerical method and IBM SPSS Statistics 23 software was used for the statistical method. Analysis was made according to different scenarios for CO2 accumulation from respiration in classrooms. In all studies, 114 different situations including 11 different scenarios were considered. The effects of different number of people, window opening area and air exchange rates on the amount of CO2 from respiration were investigated in the cases of occupied classroom with doors and windows closed, occupied classroom with doors and windows open and empty classroom with doors and windows open. In addition, as a result of the regression analysis performed with the data obtained from the numerical solutions, equations expressing the relationship between the CO2 concentration from respiration and the effective variables were developed. It was determined that in the unventilated classroom, the CO2 concentration exceeded the critical value of 1000 ppm accepted by standards within 10 to 30 minutes, depending on the number of people, and reached 4000 ppm at the end of a 1-hour lesson. In the occupied classroom with ventilation, the concentration increased with the number of people during a 1-hour lesson, and was found to be below and slightly above 1000 ppm. In the unventilated classroom, it was found that in the ventilation performed after the lesson in the empty condition, the atmospheric CO2 concentration value of 400 ppm would be approached within 15 to 60 minutes, depending on the window opening area and airflow rate.