Modeling a non-existing cooling system

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Hi All,

User's Manual, if a space has no cooling system, and it is a conditioned
space (i.e. NOT semiheated), then that space must have a cooling system
modeled and it would be identical for the proposed and baseline cases. I
completely understand the logic of this requirement - in most cases.

However, I am working on a fire station where the apparatus bay (the fire
trucks) are in a 4,000+ sq ft space that is heated only, but is a
conditioned space and not a semiheated space. This space is almost half of
the building area, will not be cooled, has large overhead doors that are
mostly open, and is a place where diesel engines run.

Does anyone out there know of any exception, or interpretation, to this
modeling rule for specific cases such as a fire station where a space can be
modeled as heated only for the baseline and proposed cases? The model will
be submitted for LEED review. I can certainly model a cooling system but it
does not seem to make sense in this case.

Thanks for your input and I really appreciate this forum.

Cheers!

Jeff Ross-Bain, PE, LEED AP BD+C

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Hi Jeff,

Look at ASHRAE 90.1-2010 systems 9 and 10 which are heating only. They also show up in addenda dn, do, dp, dq, dr to 90.1-2007.

Best wishes,
Dan

?
Daniel Knapp, PhD, LEED? AP O+M

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Correct me if I'm wrong but systems 10 and 11 wouldn't be applicable in
his case as his vehicle bay is not of the type that is supposed to be
used in system 10/11. "Thermal zones designed with heating only systems
in the proposed design, serving storage rooms, stairwells, vestibules,
electrical/mechanical rooms, and restrooms not exhausting or
transferring air from mechanically cooled thermal zones in the proposed
design shall use System type 10 or 11 in the baseline building design."

I've got a similar project that instead of vehicle bays I have heavy
truck maintenance bays/repair bays + office space for the Corp of
Engineers. They have determined that system types 10/11 can't be used
as they don't qualify due to room classifications.

Jeff - I think you might be stuck just like me trying to model cooling
in both baseline and proposed models.

Regards,

Eric
Eric Hethcoat, P.E.

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I believe you have to include the cooling system in the model (per ASHRAE), but with the cooling thermostat set-point set high (i.e. up to 90 degrees), per USGBC, which effectively makes this a moot point. Is the cooling system in the model? Yes, we met the modeling requirement. Does it have any impact on the savings? The answer would be no.

That is how I would handle this situation.

I have seen this written down somewhere, maybe a USGBC interpretation, just cannot remember where I saw this.

Regards,

JAH

James A. Hess, PE, CEM, BEMP

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As long as the cooling thermostat setpoints are identical in both models,
USGBC should approve of it. We have done this on numerous projects for
small storage spaces and stairwells.

Rob

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Thank you very much for your thoughts. This is very helpful.

Regards -

Jeff Ross-Bain, PE, LEED AP BD+C

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Jeff -

ASHRAE published Addendum dn which covers heating only systems. In this addendum you'll find two new system types - 10 & 11.

Hope this helps!

Brendan

Brendan McGrath LEED(r) AP

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Also, LEED Interpretation 10130 issued November 1, 2011 covers using Addendum dn for LEED projects:

===
For projects containing heating-only storage buildings or spaces, it is acceptable to use system types #10 or #11 from the ASHRAE 90.1-2007 Addendum modifications to the Appendix G modeling protocol whenever applicable. ASHRAE 90.1-2007 Addendum dn establishes the Baseline system type for heated only storage buildings as System Type #10 (where the proposed case heating source is fossil fuel, fossil/electric hybrid or purchased heat) or #11 (where the proposed case heating source is electric or other). Furthermore, Section G3.1.1 Exception (e) states that thermal zones designed with heating only systems in the proposed design, serving storage rooms, stairwells, vestibules, electrical/mechanical rooms, and restrooms not exhausting or transferring air from mechanically cooled thermal zones in the proposed design shall use System type #10 or #11 in the Baseline Building design (Note: this exception would also apply for an enclosed heated-only parking garage or apparatus bay). Exception (f) states that if the Baseline system type is 10 or 11, all spaces that are mechanically cooled in the proposed building design shall be assigned to a separate baseline system determined by using the area and heating source or the mechanically cooled systems.
Note: If the project is served by a District Energy System, and the project is using Option 1 of the "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" document to achieve credit compliance, then the Baseline Case System Type #10 shall be revised to a single zone constant volume air handler with purchased hot water heating.
===

Jeremy R. Poling, PE, LEED AP+BDC

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