[BLDG-SIM] Oh, what a tangled web we weave...

[Peterson, John]

The plenums subtract from the total room volume.  If the return is
ducted, this makes a large difference.  Also while the plenum & room may
have the same or nearly the same temp/humidity, ventilation rates for
the room might be calculated based on a CO2 level difference.  The CO2
calculation is based on the room volume, which relates directly with OA
needed, and hence the energy to condition that OA.  The plenum can mean
a big difference in room volume flows when extrapolated across an entire
building.  

 

John Peterson, PE, LEED AP

625 N. Washington Street     Alexandria, VA  22314 

Tel: (703) 683-9700 

Fax: (703) 683-2480 

 

________________________________

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brandon
Nichols
Sent: Thursday, July 12, 2007 6:33 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Oh, what a tangled web we weave...

 

Lynn,

 

Do you really need the plenums?  Personally I find them non-value-added
for most of our energy study work.  Suggest specifying ceiling height
equal to floor-to-floor height in the DD wizard to make them disappear.


 

Regards

 

Brandon Nichols, PE

Mechanical

HARGIS ENGINEERS

600 Stewart Street

Suite 1000

Seattle, WA 98101

www.hargis.biz

 

d | 206.436.0400  c | 206.228.8707

o | 206.448.3376  f  | 206.448.4450

 

 

 

________________________________

From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Lynn
Qualmann
Sent: Thursday, July 12, 2007 3:03 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Oh, what a tangled web we weave...

I am using eQuest to model an office building with 3 unique floors, many
spaces (with diff't use types) per floor and plenums between floors. I
have already defined the appropriate footprints for each floor and
imported them into a single model. NBD. Because there are many spaces
per floor and plenums assume the shape of the space they sit over, it
seemed like a good idea to import the plenums as separate, floor-shaped
spaces. This was to allow internal floors and ceilings of the non-plenum
spaces to be specified as NEXT-TO the appropriate plenum without any
concern for the shape of the plenum. If each space on, say, Floor1 had
an associated plenum reflecting the space shape, the spaces on Floor2
would not line up with those plenums. I defined neither a floor or
ceiling for the plenums so that interior floors and ceilings would be
part of the occupied spaces. As I'm sure many of you are thinking, DOE2
doesn't like that arrangement and requires at least two TILTs among the
interior surfaces, i.e. walls + floor, walls + ceiling or floor +
ceiling. If I put a floor in the 1st-floor plenum, I need to specify
which space it is NEXT-TO and the approach falls apart. Obviously, the
same deal applies to plenum ceilings. Has anyone got any ideas of how to
work around this? Is it better to just associate the plenums with the
spaces below them and let the chips fall where they may when the
separate floors are imported (i.e. can heat transfer from/to plenums be
ignored?)? Am I missing something really obvious?

 

Thanks in advance.

 

R. Lynn Qualmann, P.E.

SBW Consulting, Inc.

2820 Northup Way  #230

Bellevue, WA  98004

Phone:  (425) 827-0330

FAX:     (425) 822-8119

e-mail:  rlq at sbwconsulting.com

 
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