DOAU in Baseline vs. Proposed Model

5 posts / 0 new
Last post

Hello All,

For the majority of the LEED projects I work on I decouple the space
load from the ventilation load by using a dedicated outdoor air unit
(DAOU). Before GBCI took over the review process the proposed and
baseline models contained the same number of systems meaning if we used
a DOAU in the proposed model - we modeled the same unit in the
baseline. I recently received a comment to remove the DOAU from the
baseline and add the ventilation air to the space load systems. For that
particular model it didn't have a very big impact so I didn't think
twice about it.

The question - should a DOAU be modeled in the baseline case or should
the outdoor air load be added to the mechanical systems that take care
of the space load?

Thanks

Seth Spangler, LEED(r) AP

Tiger06's picture
Offline
Joined: 2011-02-14
Reputation: 0

In my opinion, it should not be modeled in the baseline building and outdoor
air should be added to the systems.
Carol

cmg750's picture
Offline
Joined: 2010-10-05
Reputation: 0

I agree to leave out the DOAS in the baseline case. The baseline case needs
to be in accordance with either Section 11 or Appendix G of 90.1, neither
sections requires a DOAS for the baseline building.

cid:image003.png at 01C9AB43.F0BEE290

Robert Gengelbach, PE, LEEDR AP

Robert Gengelbach's picture
Joined: 2011-10-02
Reputation: 0

I'm with Carol. We recently submitted a model with the systems set up that way and it was accepted.
Kimberly Killian

Original message
From: "Carol Gardner"
To: sspangle at rmf.com
Received: 4/22/2010 11:53:35 AM
Subject: Re: [Bldg-sim] DOAU in Baseline vs. Proposed Model

In my opinion, it should not be modeled in the baseline building and outdoor air should be added to the systems.
Carol

Kimberly Killian's picture
Joined: 2011-09-30
Reputation: 0

Its an interesting problem because if the DAOU is
a system has over 5000 cfm and over 70% OA the
baseline system requires heat recovery
(G3.1.2.10). I know because I asked the question
of ASHRAE as an Interpretation Request. Even
though the individual systems served by the DAOU
have less than 70% OA, the baseline systems still
require heat recovery of at least 50% effectiveness.

Chris Jones

Chris Jones's picture
Offline
Joined: 2011-09-30
Reputation: 0