Experimental determination of natural air ventilation rates based on CO2 concentration

This study reports the first results of a survey carried out by the authors on a hall used for conferences, training courses, seminars, and aimed to determine the correlation between the concentration of CO2 and the number of air changes only through natural ventilation. The assessment of ventilation rates was based on the knowledge of the indoor and outdoor CO2 concentrations and of the number of people in the hall. As it is known, the CO2 concentrations can be used as an index for the number of people present in a room and can be evaluated as a function of time by using the Meckler equation in steady-state conditions. In that case it is however necessary that some restrictive hypotheses are verified, such as the constancy of indoor and outdoor CO2 concentrations and the uniformity of the generation rate of CO2 for all the occupants.