[Bldg-sim] Heat conduction from plenum into conditioned space

[Jeff Haberl]

Good question...
 
Chris:
 
This is a tough one. To answer this I'm assuming that EQUEST uses the same reports at DOE-2.1e. If so, then
this applies, if not someone can correct me.
 
The answer lies in the DOE-2 system diagram, where you'll see that any sort of "plenum" that is used as a return
air path is actually a heat gain to the SYSTEM return air. Hence, it does not show on the LOADS report, only as
additional heat gain/loss in SYSTEMS when the system is operating. This is why the roof does not appear in the
LOADS report. For example, take a look at the SAMP1.INP file, run 3A. (...by the way...all the DOE-2 commands
are exercised one way or another in the SAMP files that come with DOE-2...with a few exceptions...).
 
If you are looking for the roof loads you'll have to connect the roof directly to the spaces (there are 5 in SAMP1.INP), and
declare the return path as direct or ducted. By switching back and forth, you can see the impact of the plenum.
 
This is not to say that plenums are trivial, as they are not. A plenum with thermal mass can be used for many interesting
things that can serve reasonably well as proxies for some rather complex models, for example passive solar. There's lots more
about this in the DOE-2 Newsletter archives at LBNL.
 
Jeff
 
FYI...I'll be teaching a webcast this semester on DOE-2 on M,W,F from 9:10 to 10:00 (central). All lectures will be recorded and I hope
to eventually hang some version of them on a web site somewhere. If anyone is interested in seeing the webcasts, please let me know 
a.s.a.p. (sorry for the short notice) and I'll see if we can open this up to a limited number of BLDG-SIM users.
 
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) :=') 8=) 8=) 8=?
Jeff S. Haberl, Ph.D., P.E.............................jhaberl at esl.tamu.edu
Professor......................................................Office Ph: 979-845-6507
Department of Architecture.......................Lab Ph: 979-845-6065 
Energy Systems Laboratory.......................FAX: 979-862-2457 
Texas A&M University..............................77843-3581
College Station, Texas, USA.......................URL: www-esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) 8=? 8=) 8=) 8=) 

________________________________

From: bldg-sim-bounces at lists.onebuilding.org on behalf of Buntine, Chris
Sent: Mon 1/5/2009 5:03 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Heat conduction from plenum into conditioned space



I'm trying to find out where the heat conduction from the plenum to the conditioned space below appears in the eQuest simulation report.  LS-B shows the roof heat conduction into the plenum but for the conditioned space below LS-B shows no roof or ceiling conduction.  Can anyone tell me whether there is another report which does show this information.

 

Thanks,

 

Chris D. Buntine, CEM, LEED AP
T 213.542.4496
F 213.542.4515
cdbuntine at greenworkstudio.com <mailto:cdbuntine at greenworkstudio.com> 

GreenWorks Studio
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Chris D. Buntine  |  Architecture  |  Direct: 213.542.4496
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