Air quality inside a school building: air exchange monitoring, evolution of carbon dioxide and assessment of ventilation strategies

Conceição, E. Z. E.; Lucio, M. M. J. R.

http://hdl.handle.net/10400.1/7539

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Authors

Conceição, E. Z. E.

Lucio, M. M. J. R.

Abstract(s)

This paper presents an assessment of indoor air quality and various ventilation strategies inside a school building located in the south of Portugal. In the first phase, ventilation rate was experimentally evaluated using the tracer gas method. In the second part, different airflow typologies were investigated and, after calculating the air exchange and flow rates for each of them, the evolution of metabolic carbon dioxide inside the spaces was numerically estimated. Ventilation measurements were made in classrooms, auditorium, offices, staff and computer rooms. The assessment of ventilation was based on evaluating the carbon dioxide produced by the occupants for three ventilation approaches; these were: one based on cross-flow natural ventilation (in current use) and two based on forced ventilation systems. In the case of the forced systems, one was based on providing a constant flow to meet the required Portuguese ventilation standard in the main occupied rooms while the other was an adjusted constant rate based on a simple calculation procedure that took into consideration the air quality needs of all the spaces including corridors and atria. This approach was developed to produce an efficient yet inexpensive ventilation approach that did not incorporate expensive sensors and control systems. Carbon dioxide evolution predictions were made using software that evaluated the thermal response and the air quality of a building with complex topology. The numerical model used to evaluate air quality, was based on mass conservation integral equations in which the final equations system was solved through the Runge-Kutta-Fehlberg method with error control. A statistical study of the occupation cycle in the school building during the day was developed.