[BLDG-SIM] Baseline HVAC Type

[Michael Rosenberg]

A number of changes have been made to Appendix G specifically to deal
with its inadequacies in modeling laboratory buildings and systems.
These will be reflected in the 2007 version of 90.1 which should be
released sometime this year. In the meantime, these changes were not
published in any official addenda, so I do not think they can be used as
allowed by USGBCs recent ruling to allow ASHRAE addenda.

Mike

Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> gail <gail22 at gmail.com> 5/15/2007 3:34:59 PM >>>
Hi Bill,

I'm of the opinion that many laboratory spaces DO meet the intent of
this
exception and MAY be modeled with PSZ systems.  The basis for my
opinion is
the 90.1-2004 User's Manual, Section 6.5.2.1, which specifically
mentions
"areas of hospitals, operating rooms, and laboratories that must be
maintained @ positive or negative pressures to prevent contaminants
from
entering" as examples of zones where special pressurization
relationships,
cross-contamination requirements, or code-required minimum circulation
rates
are such that variable air volume systems are impractical.  Also,
laboratory
spaces often have high process loads meeting or exceeding the 10
Btuh/sqft
threshold when compared against adjacent hallways, offices, and/or
classrooms.

If I were preparing LEED Documentation for a V2.2 lab building, I
would
probably provide an accompanying narrative that specifically references
the
Appendix G exception, and the User's guide Section 6.5.2.1
clarification.

Best Regards,
Gail Stranske
CTG Energetics


On 5/15/07, Bill Talbert <btalbert at aeieng.com> wrote:
>
>  Can anyone provide feedback on the intent of ASHRAE 90.1 Appendix G
> Exceptions to G3.1.1 which allow changes to the baseline HVAC
systems
> prescribed in Tables G3.1.1A and G3.1.1B for spaces with special
> pressurization requirements or spaces where peak thermal loads differ
by
> more than 10 Btu/h-sqft? This exception would appear to allow
Packaged
> Single Zone air conditioners with gas-fired heating as baseline
systems in
> laboratory spaces with high equipment loads and/or pressurization
> requirements. In a large lab building where the baseline system per
Table
> G3.1.1A is a VAV system, this could make a big difference in
calculated
> energy savings. A recent CIR (February  '07) on the USGBC site
implies that
> the exception should not be used although the question involves
reheat
> issues as well. It seems that a PSZ system could be modeled
successfully to
> meet zone conditions without reheat but does this approach
(simulating the
> baseline for a large laboratory building with multiple PSZ systems)
meet the
> intent of the exception?  Has anyone else had any experience with
this or
> can the A90.1 and LEED folks offer some perspective?
> Thanks,
>
>
>
>
>
>
> Bill Talbert, PE, LEED(r) AP
> Mechanical Systems
> Phone: (608) 441-6677
> E-mail: btalbert at aeieng.com 
>
> Affiliated Engineers Inc.
> 5802 Research Park Blvd.
> Madison, WI. 53719
> Tel. (608) 238-2616
> Fax. (608) 238-2614
>


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