CFD-based evaluation of indoor air quality and particle dispersion in classroom space with natural ventilation

Today, individuals spend a significant portion of their time indoors, and the importance of indoor air quality on human health is increasingly becoming a topic of discussion. Especially during the COVID-19 pandemic, it has been scientifically proven that inadequate ventilation in indoor spaces significantly increases the airborne spread of infection. In this context, the primary objective of this dissertation is to examine the impact of architectural design parameters such as the number, location, and size of windows on the distribution of virus particles within classroom environments and to evaluate the effectiveness of natural ventilation strategies. This study focuses exclusively on natural ventilation conditions, excluding mechanical ventilation systems from the scope of analysis. Within the scope of the research, a theoretical classroom model with a capacity of 30 students was developed, and different window opening scenarios were evaluated in a three-dimensional environment using SolidWorks Flow Simulation software. Through Computational Fluid Dynamics (CFD)-based analyses, the time-dependent distribution of COVID-19 virus particles emitted from an infected individual was examined in detail. Under three different seasonal scenarios — summer (June), autumn (October), and winter (December) — the ventilation performance of various window configurations was comparatively analyzed. Simulation results revealed that the number and location of windows play a decisive role in indoor air circulation and the particle dilution process. In particular, scenarios with four open windows significantly reduced the particle evacuation time from the classroom, indicating an increase in ventilation efficiency. The findings confirm that natural ventilation is an effective, low-cost, energy-efficient, and sustainable solution for reducing infection risk. This study provides concrete architectural recommendations for improving existing educational buildings and creating healthy indoor environments in future school designs. Moreover, the results contribute to the development of resilient and healthy building strategies, not only for COVID-19 but also for potential similar pandemics that may be encountered in the future. Keywords: Indoor Air Quality, Natural Ventilation, COVID-19, CFD Simulation, Classroom Space, Architectural Design, SolidWorks Flow Simulation