Our project are factory, the ventilation system use exhaust fans combined with louvre / open door to tranfer outside air direct from outside. 
To monitor, we consider that is natural ventilation case so we suggest owner/MEP designer install CO2 sensor at between 3 and 6 feet above the floor combined with audible alarm when CO2 concentration exceeds the setpoint by more than 10%.
Recently, in our projects, LEED Reviewers don't approve CO2 monitor, they require exhaust fans greater than 1000 CFM (1700CMH)  must be provided with monitoring devices.
It is correct?