[Bldg-sim] CAV to VAV issues in EnergyPlus

[Ryan Del Balso]

I will start out by saying I am not an EnergyPlus expert. I am trying to
convert one of the DOE commercial building E+ prototypes from a CAV system
to a VAV system to determine the energy savings. I have modified the
baseline CAV model for one of the zones thus far to a VAV system, but the
VAV model is using more energy than the CAV model. I also have a lot more
unmet hours for both heating and cooling. I cannot figure out what is
causing these issues (I assume they are related). My current guess is that
I continue to use the same cooling coil (Coil:Cooling:DX:SingleSpeed) in
the VAV model, rather than converting the coil to Coil:Cooling:DX:TwoSpeed
as I see in most of the other DOE prototype VAV models.

My questions are:
1. Is it ok to use the Coil:Cooling:DX:SingleSpeed in a VAV system, or
should I convert that to a Coil:Cooling:DX:TwoSpeed?
2. If it I convert the VAV model to the Coil:Cooling:DX:TwoSpeed is this
analogous to modifying the baseline compressor to a variable speed
compressor?

Thanks for any help.
Ryan
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