CFD simulation study and experimental analysis of indoor air stratification in an unventilated classroom: A case study in Spain

• Published in: Heliyon 2024-06, Vol.10 (12), p.e32721, Article e32721
• Main Authors: Concilio, Carmela, Aguilera Benito, Patricia, Piña Ramírez, Carolina, Viccione, Giacomo
• Format: Article
• Language: English
• Subjects: air; air quality; Air stratification; atmospheric pressure; carbon dioxide; case studies; CFD; CO2 concentration; humidity; Indoor air quality; Indoor ventilation; kinematics; mathematical models; Pollutant; prediction; Spain; temperature; Unventilated rooms
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2024.e32721

Health problems and respiratory diseases are associated with poor indoor air ventilation. We investigated the air quality inside a classroom-laboratory where no ventilation is provided. The case of study, consisting of an internal enclosure, is located at the Escuela Técnica Superior de Edificación (ETSEM) of Madrid (Spain). The high height favours air stratification which is analysed in terms of temperature and CO2 spatial distribution. Temperature, air humidity, atmospheric pressure and CO2 concentration measurements were taken in time at three different height locations. A CFD numerical model was established to analyse air quality. Flow circulation is derived by solving full 3D Navier – Stokes governing equations, coupled with the thermal problem. The diffusion problem of the CO2 produced by the inner occupants is then derived from the kinematics solution. Three scenarios were taken into account: occupants seated (1), standing (2), half seated, half standing (3). Results clearly show the air stratification as a result of density gradient, which is in turn determined by temperature difference between the occupants and the surrounding air. Temperature prediction maximum relative error is contained to 3.5 %. As expected, CO2 concentration increases over time, reaching maximum values depending on the configuration considered and height location. •Investigating Air Stratification in Classroom Labs: Crucial Insights for Healthier Environments.•3D CFD Model Unveils Air Stratification: Enhancing Comfort and Wellbeing.•CO2 Concentration Peaks Revealed: A Breakthrough Study on Indoor Air Quality.•Improving Ventilation: How Height Impacts Temperature, Humidity, and CO2 Levels.•Unlocking the Mysteries of Air: Unravelling the Impact of Height on Indoor Climate.