[Equest-users] DOAS in baseline

Bishop, Bill wbishop at pathfinder-ea.com
Thu Jan 27 08:35:02 PST 2011


Susan,
 
My short answer is no, there is nothing in Appendix G that requires you
or allows you to model a DOAS system that preconditions outside air. As
you and Nick said, first use G3.1.1 for the system type. Then refer to
G3.1.2.10 to determine if exhaust air energy recovery is required. Keep
minimum outside air requirements identical between the baseline and
proposed per G3.1.2.5. If the DOAS penalizes your proposed design from
an energy perspective, check Table 6.5.3.1.1B for potential adjustments
to your baseline fan pressure drop, per the note to Table G3.1.2.9.
 
Regards,
Bill
 
William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects
LLP
Mechanical Engineer
 
 134 South Fitzhugh Street                 Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005
wbishop at pathfinder-ea.com           www.pathfinder-ea.com
<http://www.pathfinder-ea.com/> 
P   Sustainability - the forest AND the trees. P 
________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Susan F
Sent: Thursday, January 27, 2011 11:13 AM
To: Nick Caton
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] DOAS in baseline
 
Nick,

So if my baseline is system 8 and I'm using 1 system per floor as
indicated in G.3.1.1, I don't really see an exception that would allow
the DOAS.  Am I missing something that would actually allow it?

Thanks,
Susan
On Thu, Jan 27, 2011 at 10:21 AM, Nick Caton <ncaton at smithboucher.com>
wrote:
Hi Susan!
 
Whether or not a baseline model gets a separate system for a proposed
design featuring a DOAS is dependent on a few things, including how you
decided to approach modeling the DOAS in the proposed model.
 
-          A clarification first:  Type and quantity of baseline systems
is determined first and foremost per Appendix G.3.1.1.  You generally
have either one system per floor or one system per zone, depending on
the system type.  You never start with "one system per proposed system"
except by coincidence.
-          If you use a dummy zone approach (not integrating the DOAS
into the proposed systems), and you have one baseline system serving
only the dummy zone per G.3.1.1 (or its exceptions), and you have
specified the ventilation requirements at that dummy zone (not
indirectly from the actual zones - using OA-FROM-SYSTEM for the proposed
systems)... then you'll end up with a distinct baseline system handling
the ventilation requirements analogous to the proposed DOAS.  
-          In many/most cases (partially dependant on your preferred
strategy for handling DOAS's in your proposed models), you will not have
a dedicated baseline system handling the ventilation air.  That's okay.
 
~Nick
 
 
cid:489575314 at 22072009-0ABB<https://mail.google.com/mail/?ui=2&ik=e59d6c
17d0&view=att&th=12dc815b069a7b15&attid=0.1&disp=emb&zw> 
 
NICK CATON, E.I.T.
PROJECT ENGINEER
Smith & Boucher Engineers
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
www.smithboucher.com <http://www.smithboucher.com>  
 
From: equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] On Behalf Of Susan F
Sent: Thursday, January 27, 2011 6:11 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] DOAS in baseline
 
This is not exactly an eQUEST question but y'all have been so helpful in
the past so I'm hoping you can help here too.  I'm looking for a little
clarification.  It was my understanding if you had a DOAS system that
heated and cooled the outside air before delivering it to the floor
mechanical room to be combined with return air and further conditioned
by the AHU in your Proposed building that this system would NOT be
modeled separately in the Baseline.  I cannot find anything in 90.1 that
would regulate the DOAS system and I'm not sure how you would model it.
(I understand the dummy zone concept for modeling DOAS but not sure that
would apply to the Baseline.)

Should it be separate system in the Baseline and would it be VAV or
constant volume?  And if it is a separate system what section of 90.1
would you reference for this?


Thanks in advance.
 
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