[Trace-users] Split System with DOAS for LEED (UNCLASSIFIED)

[Eurek, John S NWO]

Classification: UNCLASSIFIED
Caveats: NONE

Bob(s)

Mr. Fassbender, Your answer confuses me.

You say it is not acceptable to model as 1 system, but the image you
attached shows that you are using the "dedicated OA" tab.

The second concern I have is that my outside air unit has energy recovery,
but the fan coils do not.  Like Mr. Arnott's system, the heating and cooling
unit is return only with no outside air.  So if I make a fan coil system,
then input the information under the 'dedicated OA' tab, if I input my
energy recovery under with 'options' tab will Trace know to credit the
energy recovery to the DOA unit, because the fan coil has no energy recovey.

Mr. Fassbender, can you explain what you meant by not modeling with 1
system?

Also, I need to look deeper into the exhaust situation, thanks for the tip
before I even needed it.


John Eurek PE, LEED AP
Mechanical Engineer,
US Army Corps of Engineers
Omaha District CENWO-ED-DA
1616 Capitol Avenue
Omaha, NE 68102
Phone: (402) 995-2134
email: john.s.eurek at usace.army.mil



-----Original Message-----
From: Bob Fassbender [mailto:bob at energy-models.com] 
Sent: Thursday, February 03, 2011 4:30 PM
To: Robert Arnott; Eurek, John S NWO
Cc: trace-users at lists.onebuilding.org
Subject: Re: [Trace-users] Split System with DOAS for LEED

Robert-

Sorry, but no, it is not acceptable to model as 1 system since your model
will not match your design documents, and your LEED reviewer will probably
have a system overload and die. You do not want that blood on your hands. 


They are both very common points of confusion in TRACE (as John confirms!)
so I answered your questions at:
http://energy-models.com/forum/energy-modeling-software/trace-700/dedicated-
oa-and-split-system#comment-1261 


I posted an image too, and the post is pretty long, so I left it on the
forum.


I briefly addressed John's return air volume problem as well. Don't forget
to click the image to enlarge it!,


Bob

On Thu, Feb 3, 2011 at 3:46 AM, Robert Arnott <arnott.robert at gmail.com>
wrote:


	Hi all,
	
	I am a new Trace 700 user and I'm busy modelling a building for
LEED. I'm struggling with two fundamental aspects of how the HVAC system
modelling works in Trace.
	
	
	1. The building uses a split unit heating/cooling system, with a
completely separate dedicated outdoor air system for fresh air. The fresh
air supply is constant and does not vary with the heating and cooling load.
The split unit draws air directly from each zone (recirculating indoor air
only) and is not at all connected to the supply ducting of the fresh air.
Since there are two completely independent systems serving the same zones,
how should this be modelled for LEED? Would it be acceptable to assume that
a single system is being used, and that the heating/cooling is done directly
on the supply air?
	
	2. All zones receive fresh air, with only the bathrooms exhausting
air, creating a definite airflow network between the zones. If I set every
zone's "Adjacent air transfer from room" to the passageway connecting all
the zones, will Trace determine the correct airflow rate and direction
between each zone? Or is the adjacent air transfer directional, so that the
bathroom would need to be set to have an airflow transfer from the passage,
then the passage would need an airflow transfer from multiple zones (but
trace only allows a single zone to be set)?
	
	
	I'd appreciate any feedback. Thanks in advance!
	
	Regards,
	Robert
	

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Classification: UNCLASSIFIED
Caveats: NONE


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