[Equest-users] MAU: Dummy Zone

[estuder]

I typically make a space using the 'box' approach  having side lengths
equal to the square root of the floor area to be served by the MAU.  Do not
add any other details to this space but make it conditioned.

Next, make a thermal zone for the space.  Under the zone properties, add
the outside air requirement plus the schedule you would otherwise use to
model ventilation requirement.  Give the zone the temperature schedules you
are giving to the real spaces.  This approach assumes that the MAU is being
controlled to provide 'neutral' air to the zones being served and that
there is no impact on the zones from the ventilation air system.  You have
to be careful about not generating ghost reheat penalties or cooling
savings.

Go into the zones for the actual spaces and configure the "OA cfm" or the
OA cfm/person" values as you would normally do.  Under the systems section,
make the OA from System assignment to your MAU.  For residential modeling
where WLHPs or PTACs are used, I tend to zero out the outside air assigment
for the actual zones and assume that all exhaust and makeup cooling/heating
loads and exhaust fan energies take place in the MAU ghost zone.  Dividing
kitchen appliance energy consumption into space loads and exhausted heat
can be tricky, and definitely needs to be done if you are modeling exhaust
energy recovery.

Maybe somebody else can comment on this, but it seems to me that eQuest
cannot properly calculate the total outside air requirement in an MAU
system if DCV is used in any zone served by a system served by an MAU.  It
seems that this needs to be modeled by changing the OA minimum flow
schedule, which should agree with the occupancy schedule and the OA/person
assumptions.

I hope this is helpful.  Perhaps others have a better way to do this?

Eric

__________________

Eric Studer, PE
Project Manager
DMI
35 Walnut Street
Wellesley, MA
(781) 431-1100 ext 12
Fax: (781) 431-1109


   	-------Original Message-------
From: Erik Weiss
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] MAU: Dummy Zone
Sent: Nov 10 '10 15:27

I need to create a a dummy zone for a MAU. The building is Core and Shell,
and only the areas maintained by the owner are being modeled with FCU and
the remaining spaces (tenant) is modeled as a baseline building, following
ASHRAE 90.1 App. G. How do i create a dummy zone for the MAU (around 20,000
CFM)
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