[Equest-users] Recreating Plenum Spaces

[Nick Caton]

Connor,

 

For a 90.1 baseline/proposed comparison scenario... I'm not certain
whether a "combined plenum" in one case is acceptable.  A strict reading
of Appendix G would lead me to say "no," but if all plenum zones are
generally unconditioned spaces without systems, the only difference in
modeled behavior should be the thermal lag/buffer between adjacent
plenum zones from the partition constructions (assuming the wizards
don't make "air" type wall surfaces when generating individual
plenums...).  That would probably not be significant in many cases.  It
might make a significant difference if you have core/perimeter terminal
units using the plenum as a return air path I suppose...

 

The wizards are frankly cryptic in how they generate plenums for your
spaces - I think it involves whether you have a "system per zone"
assigned to the shell...  perhaps zone group definitions play a role,
not sure...  This has led me into the same situation, with two
comparative models having different plenum layouts.

 

I do not know of any easy/fast way to recreate or a ton of plenum zones
and their associations/surfaces between two complex models, when they've
been combined into one.  This is the sort of things that's scattered
throughout an .inp file, so it wouldn't be something easy to just
copy-paste...  if it's an option and you have the time, I would advise
trying to wrangle the wizards into creating the same plenum
configuration in both models, but it would require some guesswork to
figure out how!

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jansen,
Connor
Sent: Thursday, June 24, 2010 12:51 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Recreating Plenum Spaces

 

Hello All,

 

I'm looking for some insight on how plenum zones may or may not affect
my modeling outcome.

 

The building in question has changed from a 90.1 baseline system type 6
Packaged VAV to a system 4 Packaged Single zone. The model is currently
using a single plenum zone for the entire floor. I've noticed in the
past (correct me if I'm wrong) that when assigning spaces to HVAC
systems in the wizard it will output individual plenum spaces for
corresponding zones when using single zone HVAC systems and a combined
plenum space when using multizone systems.

 

Is it necessary to recreate the individual plenums in the detailed mode
if I switch to single zone systems? If so is there a simple way of doing
this?

 

Thank you for the help.

 

Regards,

 

Connor

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