ABSTRACT:

Indoor air quality (IAQ) and thermal comfort in classrooms are critical factors influencing students’ health, comfort, and learning performance. High occupant density, long occupancy duration, and insufficient ventilation often result in elevated carbon dioxide (CO₂) concentration, uneven airflow distribution, and thermal discomfort in classrooms. Although natural ventilation is widely used, its effectiveness is highly dependent on outdoor conditions and occupant behaviour, making it unreliable in many situations. Recent studies, particularly after the COVID-19 pandemic, emphasize the need for controlled mechanical ventilation to reduce airborne transmission risks and ensure acceptable indoor conditions. This paper presents a duct-based classroom airflow optimization approach aimed at achieving uniform air distribution and improved IAQ. Ventilation requirements are calculated based on occupancy, and an optimized rectangular duct layout is designed. Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent are performed to analyse airflow patterns and velocity distribution. The results show that the optimized duct configuration significantly reduces stagnant air zones and maintains air velocity within thermal comfort limits. The proposed approach provides a simple, practical, and effective solution for improving classroom ventilation.