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<font size="+1">No. Your over sizing will carry from the terminal
units to the plant but not the other way around. Note Bills note
about the system variance. This will also apply to the plant. It
is a little awkward though and over sizes everything.<br>
Bruce<br>
</font><br>
On 26/07/2011 02:11 PM, Arunabha Sau wrote:
<blockquote
cite="mid:CAALKp7Rsk6c1WjK2dUD_oLkxeTaeDvCz9KHxE0uBtV-MYx2Aew@mail.gmail.com"
type="cite"><font face="tahoma,sans-serif">Thanks Bill. Awesome
clarification. I appreciate your time.<br>
</font>
<div>
<div><font class="Apple-style-span" face="tahoma, sans-serif">So
I was wondering, if you oversize the Plant does the AHU get
oversized too by default, in eQuest?</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif">Any
thoughts?</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif"><br>
</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif"><br>
</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif">Much
thanks,</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif">Aru</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif"><br>
</font></div>
<div><font class="Apple-style-span" face="tahoma, sans-serif"><br>
</font>
<div class="gmail_quote">2011/7/26 Bishop, Bill <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:wbishop@pathfinder-ea.com">wbishop@pathfinder-ea.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">Aru,</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">I don’t
think the intention of G3.1.2.2 is met by
oversizing only the plant and not the systems. The
90.1 User’s Manual does not specify what is to be
oversized either, although it does describe a
chiller when discussing the differences in
equipment sizing between the ECB and PRM:</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">“For
instance, if a chiller in the proposed building is
50% oversized, then the chiller in the budget
building is also 50% oversized. However with the
building performance rating method, equipment in
the baseline building is oversized by a fixed
amount in all cases.”</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">In eQUEST,
setting the system Cool Sizing Ratio to 1.15 and
Heat Sizing Ratio to 1.25 will also increase the
autosized capacities of the plant. I believe this
is how most Appendix G modelers (including myself)
address the G3.1.2.2 requirement.</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">Note that
you could also achieve the same cooling and
heating capacity oversizing by setting the overall
system Sizing Ratio to 1.15, the Cool Sizing ratio
to 1.00 and the Heat Sizing Ratio to 1.087.
(1.15x1.087≈1.25). However, this oversizes the
system airflow by 15%, and G3.1.2.8, which
specifies how design airflow rates are determined,
does not mention oversizing. I have had models
where unmet heating/cooling hours could only be
reduced sufficiently by increasing the system
airflow as a last resort.</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">Regards,</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D">Bill</span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"><img
src="cid:part1.01020803.01020209@bellnet.ca"
alt="Senior Energy Engineer" height="116"
width="486"></span></p>
<div class="im">
<p class="MsoNormal"><span
style="font-size:11.0pt;color:#1F497D"> </span></p>
<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">From:</span></b><span
style="font-size:10.0pt"> <a
moz-do-not-send="true"
href="mailto:equest-users-bounces@lists.onebuilding.org"
target="_blank">equest-users-bounces@lists.onebuilding.org</a>
[mailto:<a moz-do-not-send="true"
href="mailto:equest-users-bounces@lists.onebuilding.org"
target="_blank">equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Arunabha Sau<br>
<b>Sent:</b> Monday, July 25, 2011 7:47 PM<br>
<b>To:</b> <a moz-do-not-send="true"
href="mailto:equest-users@lists.onebuilding.org"
target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Oversizing..AHU
or Plant?</span></p>
</div>
<p class="MsoNormal"> </p>
</div>
<p class="MsoNormal"><span>Howdy!</span></p>
<div>
<div class="h5">
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal"><span>So, I just saw a
project which has applied its oversizing
factors (1.15 for cooling and 1.25 for
heating) to the plant rather than the air
handlers. ASHRAE 90.1 Appendix G <span>page
180, G3.1.2.2 Equipment capacities does
not specify where the oversizing should
occur. Have you seen this method used
before? Is it an acceptable and accurate
way of meeting the baseline modeling
requirements?</span></span></p>
</div>
<div>
<p class="MsoNormal"><span> </span></p>
</div>
<div>
<p class="MsoNormal"><span>I appreciate your
help.</span></p>
</div>
<div>
<p class="MsoNormal"><span> </span></p>
</div>
<div>
<p class="MsoNormal"><span> </span></p>
</div>
<div>
<p class="MsoNormal"><span> </span></p>
</div>
<div>
<p class="MsoNormal"><span> </span></p>
</div>
<div>
<p class="MsoNormal"><span>Much thanks,</span></p>
</div>
<div>
<p class="MsoNormal"><span>Aru</span></p>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<br>
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