[BLDG-SIM] Baseline for Garage Ventilation using Performance Rating Method, LEED-CS 2.0

[gail]

The 90.1-2004 User's Manual states in Section 6.5.3,

"Fans that ventilate only, such as garage exhaust fans or equipment room
ventilation fans that transfer only unconditioned outdoor air, do not
qualify as a fan system in this context.  Fan systems must be part of a
system with heating or cooling capability."

The user's manual provides a few additional useful clarifications regarding
what constitutes a "fan system".

Garage exhaust fans, stairwell pressurization fans, etc. should be modeled
as miscellaneous load, with both the CFM and BHP per CFM modeled identically
(except the motor efficiency in the proposed case can be modeled as
improving upon the requirements of Section 10.4)

On 4/20/07, Scott Rushing <scottr at rushingco.com> wrote:
>
>  I've done some of the same garage exhaust fan pondering.
>
>
>
> The appendix G language is as follows:
>
> "G3.1.2.9 Supply Fan Power. System fan electrical power
>
> for supply, return, *exhaust*, and relief (excluding power to fanpowered
>
> VAV boxes) shall be calculated using the following
>
> formulas:…."
>
>
>
> The word "exhaust" in this section has led me to believe it is appropriate
> to use the G3.1.2.9 formula for the baseline garage exhaust fan kw/cfm
> calculation.
>
> I also agree the design cfm should be the same in both the proposed and
> baseline garage exhaust system models.
>
>
>
> R. Scott Rushing, PE, LEED™AP
>
> *Tel: 206.285.7106, Cell: 206.321.3300*
>
> *Rushing Company*
>
>
>  ------------------------------
>
> *From:* BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] *On Behalf Of *gail
> *Sent:* Friday, April 20, 2007 3:05 PM
> *To:* BLDG-SIM at gard.com
> *Subject:* [BLDG-SIM] Baseline for Garage Ventilation using Performance
> Rating Method, LEED-CS 2.0
>
>
>
> I would certainly like to take the Option 2 approach mentioned for all the
> projects I'm submitting, but I'm pretty sure it's not allowed:
>
> Table 11.3.1.12 specifically lists garage ventilation fans (and exhaust
> fans also) as a "Miscellaneous load".  Per the requirements of that section,
> the loads "shall be assumed to be identical in the proposed and budget
> building design"
>
> This seems to indicate that Option 1 is the only option that would comply
> with the requirements of Appendix G.
>
> Best Regards,
> Gail Stranske
> CTG Energetics, Inc.
>
> On 4/20/07, *Bill Talbert* <btalbert at aeieng.com> wrote:
>
> Neeraj,
>
> I would agree that your interpretation and your proposed 'option 2' appear
> to be meeting the requirements of App G. The LEED NC V2.2 Reference Guide
> (refer to EA Credit 1 Calculations for 'Other Systems,' page 182) indicates
> that where specific energy efficiency requirements exist in A90.1, the
> lowest allowable efficiency shall be used for the Baseline. Garage
> ventilation is included in the sample listing of 'other' systems and the fan
> power allowance should apply to that system. Not sure whether LEED CS V2.0has something equivalent.
>
>
>
> That said, I am not a LEED reviewer. It would be interesting to hear what
> others think on this as the fan power allowance is likely easy to beat for a
> ventilation only system where system pressure drop is minimal. I would
> expect that the intent of App G may not be to 'credit' these types of
> systems.
>
> Bill Talbert, AEI
>
> >>> neeraj <near_ej at yahoo.com> 4/20/2007 1:14 PM >>>
>
> Hi all,
>
>    - LEED, Core and Shell V2.0
>    - A 300,000 sqft building, 12 stories above ground located in
>    Washington DC. The baseline building is System # 8, i.e. VAV fan
>    controlled, PIU, all electric heating and cooling.
>    - *Problem Area -- To determine a correct Baseline*: In the proposed
>    design, 3 levels of underground parking garage are merely ventilated with
>    constant volume fans and they are not equipped with CO/NOx sensors ,
>    i.e. they are merely constant volume, SA and EA fans.
>    - We know that garage ventilation is not process energy, so it must
>    be regulated somehow, right?! Plus, we cannot take credit for energy savings
>    from OA ventilation air (according to Appendix G). Now, since this is a
>    'fans only' situation in both the models (no cooling or heating) I have
>    assumed the CFM of OA ventilation air must be the same in both cases. Am I
>    correct, so far?
>    - Using this as a premise, the following two contradicting scenarios
>    for an appropriate baseline model can reasonably  be thought of:
>
>
>     1. Model similar SA and EA CFM as in the "Proposed Building Model"
>       with similar fan power kW/CFM, OR
>       2. Model similar SA and EA CFM as in the "Proposed Building
>       Model" but calculating the fan power for the OA flow using Section
>       G3.1.2.9 of the Informative Appendix G of ASHRAE 90.1-2004.
>
> *THE BIG QUESTION(s)*: Is the second option a valid approach for
> determining fan power (kW/CFM) for the baseline?
>
> OR
>
> Is the method only meant for determining (and thus crediting/penalising)
> system supply air fans and not parking garage fans?
>
> Thanks,
> Neeraj
>
>
>  ------------------------------
>
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