Dear Community,
I am working on a model of a 33 story building served by separate VAV
system for core and perimeter zones. Core zones with VAV terminal units
and perimeter with fan powered boxes. All areas are served by DOAS via
the dummy zone/"OA from system" work around. I have added DCV return
sensor to the non-DOAS systems only. These systems showed appropriate
savings from this before I added the DOAS and seem ok after as well. The
problem comes when I add the ERV to the two DOAS systems. I am using ERV
settings and controls that are well tested and have worked in similar
models. That is Enthalpy wheel, 56% Sen.&Lat. effectiveness, OA Exhaust
DT at 5deg, fixed set point controls and 0.5inH2O pressure drop with
premium fans.

The issues is that as soon as I activate on the ERV the heating energy
drops by ~90% and cooling/pumps/fans triple or more. This creates 4,000+
unmet hours and overall building energy use is up 40%.

It seems like a massive heat load is being added to the system because
of the ERV, but I cant see why or how. I checked fan kW sizing and that
does not go up. Neither does supply air flow.

I would work on debugging this for as long as needed, but the deadline
looms! Attached is the model for reference. Simply turn "Recover
Exhaust?" to No to see the difference.
Jacob