Can anybody confirm if free-standing CO2 sensors that provide a visual alert to the room's occupant only (not connected to the BAS) are acceptable for this prerequisite's monitoring requirement for naturally ventilated spaces? The credit requirements indicate this is OK (audible or visual indicator OR alert the BAS) but our engineers are reading the step-by-step guidance to configure the sensor to generate an alarm "to the system operator" as needing to be connected to the BAS. This is a $50,000 add for our project as our BAS would require hard-wired sensors added to every room. I read "the system operator" of a naturally ventilated office as whoever controls the window (the occupant).
Also, has anybody proposed desktop CO2 sensors in individual offices instead of the typical 3' to 6' breathing zone (LEED definition)? Our occupants will typically be sitting at their desks and a desktop sensor would be much more representative of their breathing zone and they would always be facing the sensor so they'd be alerted to any visual alarms of high CO2 levels. The alternative of 3' to 6' would have to be wall mounted and would end up being near the door and much less visible to a seated occupant. ASHRAE 62.1-2010 defines breathing zone as 3" to 72" above the floor and at least 2 feet from walls so our desk-mounted preference comply with the ASHRAE definition and any wall-mounted (typical for LEED) does not comply with ASHRAE, but the reference guide language doesn't quite align with ASHRAE.
