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

[Tom Serra]

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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>
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