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

Scott Rushing scottr at rushingco.com
Fri Apr 20 16:31:34 PDT 2007


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, LEEDTAP

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 V2.0 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 <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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