[bldg-sim] DOE2.2-How to link two different systems to the same thermal zone?

[Justin Harrell]

I have recently modeled (in eQUEST) a building with a similar situation in which laboratory zones
with fume hood exhaust had a central make-up air system in addition to multiple water-loop heat pump
units.  The make-up air was 100% OA and conditioned to a neutral temperature by a chilled water coil
and gas furnace.  In order to simulate this I created a dummy zone, maintained at 75F supplied by
the make-up air system.  The laboratory zones were specified with their own water-loop heat pumps
and zone thermostats.  In the WLHP systems I specified OA-FROM-SYSTEM to come from the make-up air
system with a fixed CFM because the make-up air had a constant volume supply.  This forced the WLHPs
to have their fans ON at all times, so I moved the WLHP fan energy into the cooling and heating EIRs
so that the fans could run for free for the OA.  In the real building, the WLHP fans run only when
the compressor is running. This may not have been the best solution, but it gave pretty good results.

Perhaps you could do something similar by moving the reheat coil energy either into the central
system, or into the FC systems, and using the OA-FROM-SYSTEM keyword.  As far as I know, there is no
way to simulate this situation directly.  The best work-around will depend on how your systems are
controlled and what ECMs you want to simulate.

Justin Harrell
Southern Illinois University Carbondale

---------Included Message----------
>Date: 28-Mar-2005 05:48:25 -0600
>From: "Pedro Rodrigo" <pedromanuelrc at yahoo.es>
>Reply-To: <pedromanuelrc at yahoo.es>
>To: <bldg-sim at gard.com>
>Subject: [bldg-sim] DOE2.2-How to link two different systems to the same thermal zone?
>
>Hello all!
>I belong to a team of researchers in the University of
>Jaen, Spain. It would be very useful for us if you
>could
>tell us your opinion about a little DOE2-related
>question.
>We are simulating a real (yet existing) multi-zone
>building in eQuest. The problem is that we have two
>kinds of terminal units operating together in each
>zone: i) a two-pipe air handler unit (with outside air
>dampers) and ii) several two-pipe fan-coils. The AHU
>provides a primary flow of 21ºC set conditioned air.
>Users in different rooms served by the same AHU,
>operate on/off and set room temperature via the
>individual fan-coils.
>We have realized that it´s not possible to link two
>different systems (i.e. SZR + FC) to the same thermal
>zone in DOE2 (only one is allowed). How could we model
>this building without increasing too much the number
>of thermal zones? And how could we schedule the
>operation of the individual fancoils, for example
>20%-On, 40%-On, 60$-On,...? (We have up to 50 fan-coil
>units working together with a single AHU).
>Thanks in advance,
>Regards,
>Pedro Rodrigo
>University of Jaen
>
>
>		
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