Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Sounds like you have a DOAS serving zone HVAC terminal units. It seems like you could use OpenStudio to model this (would help remove some of the complexity related to airflow branches, etc.) and have an air loop representing the DOAS (what you call the AHU) and assign ZoneHVAC to the thermal zones. You can use something other than IdealLoads and just let it autosize. That way you can have constant flow systems.
In terms of metering the AHU and zone equipment separately, there may be a way of doing this, but I'm not familiar with that at the moment. As a last resort, you could use the output variables for fan and heating and cooling coil energy and DView, or I personally like the free DesignBuilder Results Viewer, to sum up the energy use independently.
