[Equest-users] Space plenums have cooling load

Tue Apr 17 16:28:32 PDT 2018

I’m happy to hear you found a resolution!

I do think it’s generally good practice to build your proposed/actual case fully before generating a prescriptive baseline, where the baseline inputs inevitably depend upon details and decisions of the proposed case.  “Starting over” with your baseline is a hard call to make before you’ve done it a few times and can perceive when that’ll be the path of least resistance.

~Nick

[cid:image001.png at 01D3D670.D4736590]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Regional Energy Engineering Manager
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
F  913.564.6380
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

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From: Jing Hong [mailto:hongjing.shirley at gmail.com]
Sent: Tuesday, April 17, 2018 5:00 PM
To: Nicholas Caton <Nicholas.Caton at schneider-electric.com>
Cc: equest-users at onebuilding.org
Subject: Re: [Equest-users] Space plenums have cooling load

Hi Nick,

Thanks for your reply. Coz my proposed U-value is worse than the baseline, it is normal that the baseline has a bit lower cooling load than the proposed. However, the plenum cooling load in the baseline is way much lower than those in the proposed, which should not be.
I figured it out. First, I realized that I should use "Plenum" instead of "unconditioned" . But it did not change too much. Second, I duplicated the proposed model, saved as Baseline, and then modified it with baseline information.
After modifying the model so many times, I might mess up some physical characteristics of the Baseline model. Starting over is easier than keeping debugging it. Especially, for a case, you cannot find the error for hours.
Hopefully, it is useful for some of you.

Jing

On Tue, Apr 17, 2018 at 4:34 PM, Nicholas Caton <Nicholas.Caton at schneider-electric.com<mailto:Nicholas.Caton at schneider-electric.com>> wrote:
Hi Jing,

It seems unintuitive to assert that your proposed case plenums has increased cooling loads – is there a good set of reasons for this?

I’m also unclear on what you mean by “it still shows cooling load for those space” – could you unpack this a little further?

Systems which use the plenums as a return air path could be a cause for why their loads are seen at the systems (though it sounds like you intend for them to be isolated).  I might start with considering the sources of heat gains to your plenums, and determining what should be happening to direct/indirect heat gains to plenums over time.   Should they be circulated back to systems responding to conditioned spaces?  Common sources would include indirect gains from ceiling lighting fixtures, envelope (skin) loads (potentially exacerbated if spandrel glass is present), and internal loads transferred hourly from conditioned spaces below and from adjacent plenums.

If I had your model in-hand, I might scan for the presence of thermostat heating/cooling schedules being assigned to your plenum spaces, or assignments to a plenum space as a master zone for specific system types.  Those could produce direct calls for airstream heating/cooling which otherwise wouldn’t be occurring.

~Nick

[cid:image001.png at 01D3D670.D4736590]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Regional Energy Engineering Manager
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
F  913.564.6380
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>

15200 Santa Fe Trail Drive<https://maps.google.com/?q=15200+Santa+Fe+Trail+Drive+%0D%0ASuite+204+%0D%0ALenexa,+KS+66219+%0D%0AUnited+States&entry=gmail&source=g>
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D3D670.D4736590]

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Jing Hong via Equest-users
Sent: Tuesday, April 17, 2018 10:43 AM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>; equest-users at onebuilding.org<mailto:equest-users at onebuilding.org>
Subject: [Equest-users] Space plenums have cooling load

Hi All,

I have assigned all the space plenum as unconditioned. But it still shows cooling load for those space, which increase the Space Cool in the report. The plenums in the proposed model have much higher cooling load than the baseline one. How could I modify it?

Thank you!

Jing

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PhD Candidate, LEED AP BD+C

School of Architecture and Urban Planning
University of Wisconsin-Milwaukee

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