[Equest-users] Dedicated Outside Air Unit

[Eric O'Neill]

Hi David,

 

I've been looking for a solution to this for a while. Modeling a DOAS
using the dummy zone (set all walls to adiabatic, or with a u-value of
0.00001) is one thing, and can be done pretty easily. All your zones can
get their OA from that zone. There's plenty of posts in the archive
<http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/>
for this (search for dummy zones), so I'll leave it there.

 

The trouble is, unless I'm missing something, you can't route the
exhaust air back to the DOAS, so your ERV won't model correctly. I've
resorted to creating an hourly report and calculating the additional ERV
savings, minus additional fan and motor losses. It's certainly not
ideal, and I haven't tried it on a LEED project yet, so I can't speak to
the acceptability to the USGBC.

 

I had taken an eQuest training class, maybe 1.5 years ago, and the
instructor had mentioned the developers were currently working on
developing a DOAS system for eQuest and they hoped to release it within
a few months, but nothing yet. 

 

If anyone has found a way to get this working properly, or has any
updates on the development in eQuest (is it in the forthcoming 3.64?),
that would be great to know. It's frustrating, because it is certainly
only going to be more prevalent in the future.

 

Eric

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of David
Everhart
Sent: Wednesday, February 24, 2010 10:14 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Dedicated Outside Air Unit

 

I have a school which will be served by ground source heat pumps.
Outside air will be provided to the classrooms with a Dedicated Outside
Air Unit/ ERV with a VAV fan which operates based on CO2 sensors within
the spaces.  The heat pumps won't have any outside air provided to them.

 

My question is what's the best way to model this?  Since you can't apply
more than one HVAC system to a particular space, do I create a fake
space and apply the outside air unit/ERV to that?  If so, how do I model
the fake space such that there is no heat loss and only people to
require outside air?

 

I tried to just model the dedicated outside air system by way of the
heat pumps, but I run into problems when trying to specify when the
dedicated outside air unit would operate.  I would want it to operate
independently from just when the heat pump is operating and I can't find
a way to do this.

 

Has anyone had any luck modeling something similar to this?

 

Thanks.

 

David B. Everhart, P.E. LEED AP

Latimer, Sommers and Associates, P.A.

3639 SW Summerfield Dr., Suite A

Topeka, KS 66614

p.  785.233.3232

f.  785.233.0647

deverhart at lsapa.com

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100224/5ad4af83/attachment-0001.htm>