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you're welcome james. now if i could only get a straight answer on
how to address baseline system sizing/outdoor air rates when the
proposed building is evaporatively cooled with 100% outdoor air ....
sizing a baseline building system of packaged dx just doesn't sit
right when the proposed is providing 20,000 cfm with 100% outdoor
air. and i get mixed comments from reviewers about too much energy
savings ... or providing too much outdoor air in the baseline ...<br>
<br>
On 10/17/11 9:31 AM, Jim Dirkes wrote:
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Dear
Patrick,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thank
you for sharing this GBCI response! It is very informative
and, while I won’t admit that I’ve been modeling anything
incorrectly, I <u>am</u> going to change a couple of things
</span><span
style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">J</span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">In
particular, I have heard on several occasions that the
Increased Ventilation credit was a clear case of “IEQ vs.
energy”; you make a decision to trade one against the
other. After reading the GBCI response below and then
double-checking with ASHRAE 90.1, I find that they are
consistent with each other and effectively allow no penalty
for the increased energy caused by increased ventilation.
Very curious, considering there is no science which
demonstrates a health benefit for outdoor airflows greater
than that required by ASHRAE 62.1!<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
other item is that I failed to notice (and still can’t find)
anything in 621.1 which says that unoccupied ventilation
should be zero. I guess that is OK, but is also curious,
since a portion of the ventilation calcs in 62.1 include
consideration for off-gassing materials (which are always
present.)<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">All
in all, I’m smarter than I was as a result of your post, so
it’s a good day! Thanks again.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal" style="text-align:center" align="center"><b><span
style="font-size:13.5pt;font-family:"Calibri","sans-serif";color:#1F497D">The
Building Performance Team<br>
</span></b><b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">James
V. Dirkes II, P.E., BEMP , LEED AP<br>
</span></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">1631
Acacia Drive NW<br>
Grand Rapids, MI 49504<br>
616 450 8653<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
<a class="moz-txt-link-abbreviated" href="mailto:bldg-sim-bounces@lists.onebuilding.org">bldg-sim-bounces@lists.onebuilding.org</a>
[<a class="moz-txt-link-freetext" href="mailto:bldg-sim-bounces@lists.onebuilding.org">mailto:bldg-sim-bounces@lists.onebuilding.org</a>] <b>On
Behalf Of </b>Patrick J. O'Leary, Jr.<br>
<b>Sent:</b> Monday, October 17, 2011 11:46 AM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a>;
<a class="moz-txt-link-abbreviated" href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</a><br>
<b>Subject:</b> [Bldg-sim] usgbc response to outdoor air
question<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">back in september there was a thread about
what the outdoor air rate in a baseline simulation should be
compared to a proposed simulation, specifically when one is
adding 30% more outdoor air to meet the ieqc2 requirement and
earn 1 leed point. there were differences of opinions about
the flow rates between baseline and proposed being either the
same (as required in 90.1 app g) or the baseline being the
calculated per 62.1 and the proposed being as designed.<br>
<br>
so i submitted a support request to the usgbc and the reply i
received is below, but in short the response is that unless
you're using dcv optionally the outdoor air rates in the
baseline and proposed energy simulations for eac1 should be
the same. the response below gives the standard responses to
differing outdoor air rate scenarios.<br>
<br>
regards,<br>
patrick<o:p></o:p></p>
<p>[Fwd: Case 00531150: General LEED Questions<o:p></o:p></p>
<p>-------- Original Message --------<o:p></o:p></p>
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<p class="MsoNormal" style="text-align:right"
align="right"><b>Subject: <o:p></o:p></b></p>
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<td style="padding:0in 0in 0in 0in">
<p>Case 00531150: General LEED Questions [
ref:00D49UeD.5004GN692:ref ]<o:p></o:p></p>
</td>
</tr>
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<td style="padding:0in 0in 0in 0in" nowrap="nowrap"
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<p class="MsoNormal" style="text-align:right"
align="right"><b>Date: <o:p></o:p></b></p>
</td>
<td style="padding:0in 0in 0in 0in">
<p>Mon, 17 Oct 2011 06:54:51 +0000 (GMT)<o:p></o:p></p>
</td>
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<td style="padding:0in 0in 0in 0in" nowrap="nowrap"
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<p class="MsoNormal" style="text-align:right"
align="right"><b>From: <o:p></o:p></b></p>
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<td style="padding:0in 0in 0in 0in">
<p>"No reply GBCI" <a moz-do-not-send="true"
href="mailto:no-reply@gbci.org"><no-reply@gbci.org></a>
<a moz-do-not-send="true"
href="mailto:no-reply@gbci.org"><no-reply@gbci.org></a><o:p></o:p></p>
</td>
</tr>
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<p class="MsoNormal" style="text-align:right"
align="right"><b>To: <o:p></o:p></b></p>
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<td style="padding:0in 0in 0in 0in">
<p>patrick@<o:p></o:p></p>
</td>
</tr>
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<p><o:p> </o:p></p>
<p class="MsoNormal">Dear Patrick,<br>
<br>
Thank you for contacting the Green Building Certification
Institute. <br>
<br>
You ask very good questions related to the relationship
between ASHRAE Standards 62.1 and 90.1, and how these
standards are applied across multiple LEED Rating System
prerequisites and credits.<br>
<br>
The simple answer to your question is that, for systems
without demand controlled ventilation, the outdoor air
included in EA Credit 1 energy simulations must be the same in
the Baseline and Proposed cases. If the project is attempting
IEQ Credit 2 Increased Ventilation, then the values calculated
in IEQc2 must be used in the EAc1 Basline and Proposed case
energy models. Note that IEQc2 does not limit the project to
providing only 30% more outdoor air than AHRAE 62.1
Ventilation Rate Procedure minimums, so higher amounts are
acceptable, as long as they are modeled identically in both
the Baseline and Proposed case energy models.<br>
<br>
The following generic LEED Review Comment applies to
ventilation systems that do not have demand controlled
ventilation:<br>
<br>
It is unclear whether the minimum outside air rates (in CFM)
were modeled identically in the Baseline and Proposed case for
all zones not having Demand Control Ventilation in the
Proposed case. Please confirm that minimum outside airflow (in
units of cfm) was modeled identically in the Baseline and
Proposed cases using the proposed case rates. Additionally,
please 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 should be modeled identically in the
Baseline and Proposed case).<br>
<br>
The situation becomes a bit more complicated in you have
systems that have demand controlled ventilation (often
implemented as Carbon Dioxide control of outdoor air or as
programmed control of outdoor air based on occupancy sensors.)
In this case the Baseline case energy model must include the
minimum outdoor air as determined by the ASHRAE 62.1
Ventilation Rate Procedure calculations for all systems having
demand controlled ventilation. <br>
<br>
The following generic LEED Review Comment applies to
ventilation systems that do have demand controlled
ventilation:<br>
<br>
Demand control ventilation was modeled for credit in the
proposed case. Appendix G allows schedule changes for demand
control ventilation as approved by the rating authority (Table
G3.1#4(Baseline)). As the LEED Certification rating authority,
GBCI requires that the outside air ventilation rates for the
Baseline case be modeled using minimum ASHRAE 62.1-2004 (or
2007 for LEED-NC 2009 projects) rates wherever credit is taken
for demand control ventilation in the Proposed case. The
proposed case minimum rates at design conditions should be
modeled as designed. Please verify that the Baseline Case
model reflects ASHRAE 62.1-2004 (or 2007) minimum rates for
any spaces where credit is taken for demand control
ventilation, or revise the model accordingly. For all other
spaces, please confirm that minimum outside airflow (in units
of cfm) was modeled identically in the Baseline and Proposed
cases. Additionally, please verify that all systems in both
the baseline and proposed cases 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 should be modeled
identically in the Baseline and Proposed case).<br>
<br>
Finally, even though you don't address energy recovery in your
question, whether or not you have energy recovery in your
ventilation systems may affect how much better (or worse) your
Proposed case energy models perform in relation to your
Baseline case energy models. <br>
<br>
The following generic LEED Review Comment addresses energy
recovery in EAc1 energy models as it relates to ventilation
systems.<br>
<br>
Energy recovery is modeled for credit in the Proposed case.
Please provide further information regarding the energy
recovery efficiency, verify that outside air is modeled with
zero flow in both the Baseline and Proposed cases during
unoccupied periods 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 should be
modeled identically in the Baseline and Proposed Case), and
indicate the bypass mechanism used to bypass the energy
recovery during mild conditions. <br>
<br>
I hope that helps, but if you have any further questions or
concerns, please feel free to use the contact form at <a
moz-do-not-send="true" href="http://www.gbci.org/contactus">http://www.gbci.org/contactus</a>
and select "Follow up to GBCI Response," inputting your case
number from this email's subject line.<br>
<br>
Best Regards,<br>
<br>
Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C<br>
<br>
Green Building Certification Institute <br>
2101 L Street NW, Suite 500 <br>
Washington, DC 20037 <br>
800-795-1746 (phone)<br>
202 828-5110 (fax) <br>
<a moz-do-not-send="true" href="http://www.gbci.org/contactus">www.gbci.org/contactus</a><br>
<br>
The text above represents a staff opinion of a particular
issue, and does NOT set any precedent to be upheld during a
LEED Certification Review. For official rulings in advance of
a LEED Certification Review, customers should utilize the
Formal Inquiries process available in LEED Online that results
in a Project Credit Interpretation Ruling (Project CIR) and
possibly a LEED Interpretation (formerly CIRs or Public
Rulings). Applications for LEED Certification will be
thoroughly reviewed based on USGBC Member balloted and
approved LEED Rating Systems, with addenda, and USGBC approved
LEED Interpretations, or Project CIRs administered by GBCI, as
applicable. Please note that certain inquiries submitted to
USGBC are forwarded to GBCI for reply as appropriate.<br>
<br>
<br>
_______________________________<br>
CUSTOMER EMAIL ADDRESS: <br>
patirck@<br>
<br>
CUSTOMER INQUIRY:<br>
I am trying to verify what the minimum outdoor airflow rate
required for EAc1 is and am not sure if this requires a CIR. <br>
<br>
If the Proposed outdoor air ventilation is a minimum of 30%
higher than the minimum required by ASHRAE 62 in order to
achieve 1 LEED point for credit IEQC2 is the Baseline outdoor
air rate also 30% higher than the minimum required by ASHRAE
62? or would the Baseline outdoor air ventilation rate be the
minimum outdoor air rate per ASHRAE 62 calculations. <br>
<br>
In other words, if ASHRAE 62 requires a minimum of 1,000 CFM
of outdoor air, and 1,300 CFM is provided to attain 1 LEED
point via IEQC1, is the Baseline outdoor air flow rate 1,000
CFM or 1,300 CFM in the energy simulation? <br>
<br>
90.1-2007/2004 both say the minimu m outdoor airflow rates
shall be the same for both the proposed and baseline building
designs, as does the user manual. <br>
<br>
But this logic seems to reward the Proposed simulation by
conditioning the additional outdoor air supplied (300 cfm in
the example above) to achieve IEQC1 in the Baseline system as
well as the proposed. <br>
<br>
The logic of using the minimum required in the Baseline case
is reflected in EAC1 in the equipment efficiency requirements.
Baseline efficiencies are the minimum required, e.g. SEER 13
for packaged units. <br>
<br>
It is the intent of the requirement that I am not sure is
clear. Increasing the outdoor air ventilation rate increases
the energy used to condition the outdoor air, so if the intent
is to put the onus on Proposed design to show energy
reduction/LEED compliance over the 90.1/62 requirements
shouldn't the Baseline outdoor air be the minimum air flow
rate per the ASHRAE 62 calculations? This puts the onus on the
design team to provide a design that compensates for the
increase in energy to meet IEQC2 by providing some method of
processing the increase in outdoor air while still reducing
energy consumption.<o:p></o:p></p>
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