Alphabet soup here.

I am working on a project that uses return sensors in the air handling unit
to modulate outdoor air and an ERV to recover energy prior to delivering
ventilation air to the spaces. Here's the thing, when I have DCV-return
sensors specified, I am showing almost no savings for the ERV (about 0.1%).
I have airflows specified as cfm/person and the occupancy schedule
definitely varies. Has anyone run into this or have a solution?

The funny thing is that if I instead specify that the CO2 sensor is located
at the zone level and outdoor air is modulated as a sum of the zones, then I
do show savings due to the ERV, although about 1/3rd of the savings if no
DCV were installed. Is this an ok substitution?? Any thoughts or
discussion is appreciated.

Thanks,

--
Karen