[Bldg-sim] Garage Ventilation and LEED Credit EA-1

Peter Alspach peter.alspach at arup.com
Wed Feb 13 08:36:28 PST 2008


Fred, we are in the process of submitting for CO VFD fan control credit.
I feel that this is still a valid ECM from a LEED perspective for
several reasons:
 
1) the code allows simple fan staging as an alternate compliance path.
However, with no min. # of fans specified one often end sup with just 1
or 2 fans per level. Staged control in this case will not be equivalent
to VFD control.
2) local utilities provide incentives for VFDs , which is a strong
indicator that staged is the default and there are energy savings
available.
3) code allows simple occupancy based controls (on during the day, off
at night) under certain conditions (generally for garages less than
30,000 SF).
 
We are using the code minimum as our definition of standard practice.
Fan powers equal in both cases, just control differences. Have yet to
get feedback from USGBC, but it seems rational to me given other ECMs
that have been credited.
 
Peter

________________________________

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Aleka
Pappas
Sent: Wednesday, February 13, 2008 8:22 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Garage Ventilation and LEED Credit EA-1


I agree that CO sensor-controlled garage ventilation is standard
practice and the USGBC should not be allowing savings claimed from this
control method.  But we've submitted a number of projects for LEED with
the Baseline fans on all the time at 0.75 cfm/SF, and assumed the fans
on about 1/4 of this time in the Proposed Building, and the USGBC has
allowed it.  We've always stated our assumptions explicitly.  There
should be a CIR to resolve this, but so far it's been hard to find
motivation on a project to spend the 200 bucks to force them to give the
project 1 less LEED point.  It's actually a huge issue for our high-rise
condo and office projects....they would be stretched to say the least to
reach the 2 required points without being able to claim these savings.
Which I think would be a good thing. 

I've also worked with a few code jurisdictions around the country who
similarly allow savings from CO vent. control to calculate energy
reduction incentives.  

If there's a USGBC person listening in, perhaps they could resolve the
issue with a freebie CIR?  

Aleka


On Feb 13, 2008 7:37 AM, Fred Porter <FPorter at archenergy.com> wrote:


	All,
	While I'm still on my first cup of coffee, and considering the
PRM, general "baseline/budget/reference" model philosophy, and others'
views on safe ventilation, another answer would be the default
"baseline" = "proposed" operation and equipment, where the PRM does not
specifically state a baseline. (You could still take credit for a
premium efficiency fan motor.)
	 
	I certainly suspect that savings have been granted to parking
garage "DCV" by lenient reviewers, but it has not surfaced in a CIR.  Of
course, clients might think it tacky of us to ask for stricter
limitations and reduced savings and points in a CIR they pay for, which
is a problem with the process. The fact that the baseline is unclear to
experienced EA Cr1/PRM modelers says a lot, since there must be a couple
million sf of ventilated parking garages rated or in the pipeline.
	 
	Oh yeah, and what about those heated parking garages under every
"green" office and resort hotel? 
	 
	And as far as "substituting" the cooling tower fan during
summer; I would think drawing air through the garage with the CT fan
would add some constant load to, or reduce the flow through, that fan,
partially offsetting savings from turning off the garage fan (which
would have operated at a low load factor if controlled by the typical
sensor). 
	 
	Off to work;
	Fred


	>>> "Fred Porter" <FPorter at archenergy.com> 2/12/2008 2:27 PM >>>
	
	>>> "Michael Tillou" <michael.tillou at gmail.com> 2/12/2008 1:31
PM >>>
	
	Does anyone know if USGBC is allowing credit for CO Control of
parking garage ventilation?  If anyone has any experience with
successfully getting credit for this efficiency measure can you please
let me know.  I am curious what is considered a reasonable baseline.
	 
	
	Dear Colleagues;
	Short answer: I sure hope not!
	 
	I very much believe the "reasonable" baseline is CO sensors, so
you would schedule the airflows (thus power, if all goes correctly in
model land) proportional to some assumed activity schedule. (There is a
good summary of what those flows might be in an ASHRAE Jrnl that's about
ten years old but on the AJ website.)  CO control is pretty much SOP; I
think the IMC, or one of the codes around here, went up to 1.25 cfm/sf
constant venting unless CO sensors are used; pretty much assuring
everyone uses sensors. There may still be a code req'd floor on the min
vent rate even w/sensors. And, in all but the smallest garages, staged
fans are typical. MAYBE someone could invent some rationale that if
there were some long ducts serving a deep garage, then VSD fans might
have a SLIGHTLY lower operating W/cfm and closer tracking of actual
req'd dilution air. But not by much.
	 
	Sure it sounds like "DCV" and the PRM sez we can take credit for
that; but we would be creating a baseline considerably worse than
typical construction, even 5-10 year old construction. And certainly we
can't use 0.7 W/cfm in this baseline. This is why when we get proposals
from savvy clients, they specify bldg maximum Btu/sf or kWh/sf or
emissions/sf; not some "savings" vs. an artificial baseline. 
	 
	Fred
	 
	P.S. Today's Puzzler: What ASHRAE PRM category does a heated
parking garage fall into? Does it matter if the heating capacity is more
than the semi-conditioned space Btuh/sf rate? 


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