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

[Chris Jones]

Is there a documented why to predict the run time 
hours for these type of exhaust/pressurization 
systems?  It seems to me they are quite intermittent with a low utilization.

At 08:02 PM 4/20/2007, gail wrote:
>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 
><<mailto:scottr at rushingco.com>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: 
><mailto:BLDG-SIM at gard.com>BLDG-SIM at gard.com 
>[mailto: BLDG-SIM at gard.com] On Behalf Of gail
>Sent: Friday, April 20, 2007 3:05 PM
>To: <mailto:BLDG-SIM at gard.com>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 <http://11.3.1.12>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 
><<mailto:btalbert at aeieng.com>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 V2.0 has 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 
> <<mailto:near_ej at yahoo.com>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:
>    * Model similar SA and EA CFM as in the 
> "Proposed Building Model" with similar fan power kW/CFM, OR
>    * 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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Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel.  416-203-7465
Fax. 416-946-1005



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