Increasing which of the following variables will require an increase in the outdoor airflow rate...

The outdoor airflow rate is the amount of outdoor air that is supplied to the building by the ventilation system to dilute indoor air pollutants and provide fresh air for the occupants.  The outdoor airflow rate depends on the ventilation standard that the project follows, which can be either ASHRAE 62.1-2010 or CEN Standard EN 15251-2007 1 . Both standards specify the minimum outdoor airflow rate per person and per unit area for different occupancy types and zones. Therefore, increasing the number of occupants will require an increase in the outdoor airflow rate to maintain the minimum ventilation level. The other variables, such as supply air velocity, system ventilation efficiency, and supply air temperature set point, do not directly affect the outdoor airflow rate, although they may influence the energy consumption and thermal comfort of the ventilation system.