[Equest-users] GBCI comments on DCV (Carol Gardner)

[James Hansen]

I'm not sure I really understand what the fuss is about.  If you're
designing and modeling a building that does NOT have DCV, then it seems
entirely fair (and accurate) to model the same ventilation rates in both
the baseline and the proposed.  If, however, you are implementing a DCV
strategy, then regardless of what you set your "maximum" OA rate at for
the proposed model, in reality, the DCV system is going to keep OA flow
rates near or below the ASHRAE 62.1 requirements (in real life
operation).

 

If the TAG committee didn't require you to model the baseline building
at ASHRAE 62.1 flow rates when DCV is being implemented, then
theoretically you could input an astronomically high OA flow rate for
both models, knowing that your proposed model would NEVER run at such a
condition and would have an unfair advantage.

 

This seems like an entirely acceptable and fair ruling.  What am I
missing?

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Karen
Walkerman
Sent: Tuesday, July 27, 2010 9:05 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

 

Is anyone on this list-serve on the EA Credit 1 committee, or know
someone who is?  If the the GBCI or USGBC has changed the modeling
requirements and is only letting modelers know during the documentation
review stage, I find this very disturbing for a number of reasons.  It
would be great if we can get some straight answers on this from someone
at one of these organizations who actually knows what is going on.

 

I am happy to draft an email outlining concerns, but I don't know who to
send it to.  If anyone does, or would like to help me with this, please
feel free to contact me directly.

 

Thanks,

 

--

Karen Walkerman

 

On Tue, Jul 27, 2010 at 8:28 AM, Peter Worley <peter.worley at arup.com>
wrote:

Sorry for what may seem like a dumb question... 

 

Why, if you're designing to ASHRAE 62.1, would you increase the outside
air quantity beyond the minimums (unless required for lab exhaust, etc)?

 

I have a project where the local code (referencing IMC 2003) requires a
higher level of minimum ventilation than ASHRAE 62.1. I've therefore
designed to this amount and modeled it in both my proposed and baseline
cases. I can't imagine that this will be problematic. Do you disagree?

 

Thanks,

Pete

 

 

Peter Worley

Mechanical Engineer

 

155 Avenue of the Americas  New York  NY  10013  USA

t +1 212 229 2669  d +1 212 897 1339  

f +1 212 229 1056

www.arup.com

 

 

 

From: Tom Serra [mailto:tserra at emoenergy.com] 
Sent: Monday, July 26, 2010 12:14 PM


To: Karen Walkerman
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

 

No documentation exists supporting the new method.  GBCI is pulling the
"rating authority" card and implementing their own requirements.   I
tried to argue my case that they are going against the procedure in
ASHRAE, but they did not change their requirement.  I have expressed my
opinion that a document should be posted on the website that shows this
new requirement but I have yet to see anything new.  Otherwise you may
be expecting savings from DCV that will be rejected and then the MEP or
modeler will look foolish.  They should have implemented a cut-off date
for projects already in the system similar to the "District Thermal"
change they made in May 2008.



In reality the DCV will still result in energy savings but the paper
design savings will be lost.  I believe GBCI and USGBC are trying to
prevent "gaming" of the system.  A designer could grossly oversize the
ventilation system and then gain tremendous savings by implementing DCV.
This new requirement forces the designer to pursue other ventilation
strategies if they want to claim savings for DCV.  Unfortunately the
only way we are learning of this requirement is through clarification
questions.  This lack of communication is what really upsets me.

The only solution that I see is that all spaces with demand control
ventilation should be designed to ASHRAE 62.1 minimums.  Also, teams
should not pursue the 30% increase ventilation credit.  

Thomas Serra
Project Manager
EMO Energy Solutions, LLC
3141 Fairview Park Drive, Suite 450
Falls Church, VA 22042
voice 703-205-0445 ex-113
fax 703-205-0449



On Mon, Jul 26, 2010 at 11:22 AM, Karen Walkerman <kwalkerman at gmail.com>
wrote:

Can anyone find documentation requiring the baseline to use ASHRAE 62.1
ventilation rates?  The table in EA Credit 1 under HVAC System Selection
for the baseline design states:

 

"Outdoor ventilation rates should be identical to the proposed case"

 

There are no exceptions listed anywhere in the LEED documentation (I am
currently looking at LEED 2009, but have reviewed this in the past under
LEED 2.2).

 

We have had DCV be approved in the past with no questions.

 

--

Karen

 

On Mon, Jul 26, 2010 at 11:08 AM, Tom Serra <tserra at emoenergy.com>
wrote:

	I've had many comments.  They have changed their perspective as
the rating authority and are requiring outside air treatment procedures
that are outside of ASHRAE 90.1 section G procedures.  Typically design
outside air volume is the same between the baseline and proposed, but if
you are using DCV they now require you to model the baseline with the
minimum ASHRAE 62.1 volume.  So, if you have greater OA volume in your
proposed model, you may be penalized depending on your DCV method and
diversity schedule for occupants in the area with DCV control.
	
	Here is an example  clarification question:

	1.       CLARIFY:  Demand control ventilation was modeled for
credit for RTU1 and RTU2 in the Proposed case as indicated in Table 1.4
of the Template; however, the outdoor air volume for RTU1 and RTU2 in
the Baseline model was not modeled at the ASHRAE 62.1-2004 minimum rates
(1,066 cfm for each RTU) as determined in EQp1: Minimum IAQ Performance.
Appendix G allows schedule changes for demand control ventilation as
approved by the rating authority (Table G3.1.4(Baseline)). As the rating
authority, GBCI requires that the outside air ventilation rates for the
Baseline Case be modeled using minimum ASHRAE 62.1-2004 rates wherever
credit is taken for demand control ventilation in the Proposed Case. The
Proposed case minimum rates at design conditions must be modeled as
designed.

	 

	TECHNICAL ADVICE:  Revise the Baseline model so the minimum
outdoor air volume is modeled at 1,066 cfm for RTU1 and RTU2 in the
Baseline model. In addition, provide revised SV-A reports for RTU1 and
RTU2 reflecting the changes. Further, verify that all systems in both
the Baseline and Proposed case are modeled with zero outside air flow
when fans are cycled on to meet unoccupied setback temperatures unless
health or safety regulations mandate an alternate minimum flow during
unoccupied periods (in which case, the unoccupied outside air rates must
be modeled identically in the Baseline and Proposed Case).
	
	
	Thomas Serra
	Project Manager
	EMO Energy Solutions, LLC
	3141 Fairview Park Drive, Suite 450
	Falls Church, VA 22042
	voice 703-205-0445 ex-113
	fax 703-205-0449

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