I have a packaged Dx Cooled VAV Rooftop unit with gas heat (for morning warm-up) that provides air to a mixture of VAV box types.  The perimeter zones are served by parallel fan powered VAV boxes and the interior zones are served by single duct/ straight VAV boxes.  Both box types have electric reheat.

In Trace do I treat these as two separate systems for the purpose of modelling?  A PFP VAV system and a single duct VAV system?  There is obviously a difference in energy usage between the two box types, since the PFP boxes utilize fan power in the heating mode, but are having to only re-heat higher mixed air temperature.  The single duct boxes are having to re-heat colder air, but have no fan energy consumed.

And am I correct in thinking the gas heat exchanger at the RTU would be the "pre-heat" coil, and the electric heaters at the VAV boxes serve as both the "main heat" and "re-heat" coils?