Hello, we have a project that is naturally ventilated, but doesn't have direct exhaust airflow (offices are ventilated through a central atrium, atrium is naturally ventilated with gravity ventilators up at the top).  So it seems like we have to either provide alarms at every single operable window in offices, or place CO2 monitors in every office.  We're trying to figure out the intent behind this requirement - does the alarm have to be audible, or can it be a visual and/or remote alarm?  and does it have to be connected to the BAS system?  Anyone have info on this?