[bldg-sim] eQUEST Dedicated Outdoor Air Systems with Zonal Fan-Coil/Heat Pumps

Barnes, Benjamin Benjamin_Barnes at nrel.gov
Thu Jul 27 23:12:02 PDT 2006

I'm working on modeling buildings with dedicated outdoor air systems (DOAS) which supply OA to every zone and recieve the exhaust from every zone (with heat recovery).  Furthermore, each zone has its own fan-coil or air handler with its own heat pump.  The one-system-per-zone limitation seems like a major obstacle.  Right now I hava a VAV supplying some core zones and all other zones served by PTACs with heat pumps.  The PTAC-served zones draw their outside air from the central zones.
Troubles are:
1. I can't tell where the air from the PTAC zones exhausts to and I can't think of a way to ensure the benefit of the heat recovery in the DOAS.  I have not specified exhaust fans for the PTAC zones.
2. The DOAS is also supplied by a heat pump, so I define the CHW loops as the 2-pipe default and specify the heat source as "heat pump" but when I run the simulation, it won't get past calculating the loads and the output file says "caution: no heating/cooling equipment defined" at the bottm.
Is there a better (possible?) way to do this?  When I try to employ systems with zonal heating, none seem to have a heat-pump option at both the zone and system level.  I don't fully understand why I must specify a CHW loop for the VAV that I use to represent the DOAS when I want the cooling source to be a heat pump.
Any advice?  Sorry for all the questions, I would greatly appreciate any help.
Ben Barnes

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