Dan,
As an alternative to using dummy zones, I suggest trying an alternative workaround ("plenum method") I have advocated for, which may be appropriate depending on how you would design your active chilled beam system. (If your system would be constant volume, without a separate DOAS, you could just model it with the Induction Unit system type. If you want to allow for variable flow, and/or separate DOAS unit, read on.) I have had luck modeling DOAS by creating separate systems (as they are designed) and assigning them to the plenum spaces above the occupied spaces. The description of how to do this, and the merits and potential drawbacks, can be found in the "NEW (?) eQUEST DOAS workaround using plenum spaces" thread in his archive: http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/2013-November/thread.html. It would be an easy alternative for you to try modeling in your schematic model, as you have few zones and they all have plenum zones above them. Also, note that while you said your static is the same in both models, you have 1" static on supply and exhaust for the heat recovery portion of the DOAS systems, which you did not include in the VAV model. This is about 90,000 kWh as shown on the ERV reports.
Regards,
Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
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