Evaluation of Air Exchange Rate and Particulate Matter Deposition Rate in a Classroom

¹ Univ Coimbra, ADAI, Department of Mechanical Engineering, Rua Luís Reis Santos, Pólo II, 3030-788 Coimbra, Portugal
² School of Architecture, Planning, and Design, Mohammed VI Polytechnic University, Lot 660, Hay Moulay Rachid Ben Guerir, 43150, Morocco

^* Corresponding author: johnogundiran@efs.uc.pt

Abstract

School buildings remain important indoor spaces where the typical occupants spend a significant amount of time. Thus, adequate indoor environmental quality (IEQ) is necessary for a safe environment and assures minimal risk to occupants’ health, well-being, performance, and productivity. This study was performed within the framework of the 3SqAir research project, an Interreg Sudoe project on school indoor air quality (IAQ), at the University of Coimbra demo site. Using experimental and numerical methods, the study evaluated the IAQ, assessing the air exchange rate (λ_V) and Particulate Matter (PM) deposition rates for different natural ventilation modes. Using the indoor CO₂ concentration and decay evolution as a proxy, the deposition rates of particulate matter (PM1, PM_2.5, PM₄, and PM₁₀) in six cases for two distinct scenarios: A (without HVAC) and B (with HVAC). A continuous IEQ monitoring system with a data acquisition cloud platform was used. The preliminary findings emphasize that PM size influences aerodynamic behaviors and deposition rate, whereas increasing natural ventilation viz-a-viz infiltration rate reduces indoor CO₂ levels. Also, the results suggest that PM deposition rates also increase as the air exchange rate (ACH) increases. It gives a preliminary premise for broader parametric investigations on IAQ in various ventilation strategies, including the ACH, airflow, and velocity distribution in classrooms.