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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Sorry, I thought I had written a response to this query but can’t
seem to find it!<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'>On a general note, anyone seeking to better understand the
intent behind various parts of 90.1 Appendix G would be well advised to borrow
or purchase the 2007 User’s manual.<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'>Here are my condensed thoughts – the user’s manual
supports some of this directly:<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span
style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The oversizing factors appear analogous to “safety factors”
in real-world design, but they exist in 90.1 primarily because it’s recognized
the capacity of the baseline systems is an easy means of cheating the system.
One could very easily decrease relative baseline performance by undersizing or
oversizing the baseline equipment.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span
style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>With that in mind, and because the loads handled by the baseline
systems are arbitrarily by a unique load profile, 90.1 has to set something as
the sizing factor. To be fair to real-world systems which are often
oversized, both for “safety factors” and because various equipment
operates more efficiently at <100% capacity, oversizing factors above 1.0
have been set. <o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span
style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I think oversizing factor for heating is larger than cooling
primarily because that reflects real-world design for packaged equipment
selection. After calculating desired loads (and applying design safety
factors), packaged equipment is often selected first on the desired cooling capacity,
and then heating options are considered secondarily. Where heating capacity
options are finite, the result is often heating elements which are oversized some
degree beyond the design heating load.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span
style='mso-list:Ignore'>4.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I would discourage the mindset that oversizing factors are
necessary to prevent unmet heating/cooling hours. They may <u>mitigate</u>
unmet hours, particularly those occurring as thermostats are coming out of
setback periods (morning warmup), but baseline system capacity is rarely the root
problem in my experience. In my mind, if a baseline is set up correctly,
oversizing factors of 1.0 ought to result in sufficient auto-sized capacity.<o:p></o:p></span></p>
<p class=MsoListParagraph><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'>There are inherent “uncertainties” to energy modeling,
just as with any HVAC load calculation, water or electrical service size
calculation, lighting maintained illuminance calcs, LRFD structural design loads
and so on. Very little in world of building design does not have some
sort of assumed future uncertainty worked into the design via “safety
factors,” both prescribed by code and self-imposed as standard practice.
In that context, I don’t believe the 90.1 oversizing factors speak to any
uncertainty that’s unique to energy modeling.<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'>~Nick<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'><img width=119 height=37 id="Picture_x0020_1"
src="cid:image001.jpg@01CBEDEC.65C6E730" alt="cid:489575314@22072009-0ABB"></span><b><span
style='font-size:11.0pt;font-family:"Stylus BT","sans-serif";color:#2D4D5E'><o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Stylus BT","sans-serif";
color:#2D4D5E'><o:p> </o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Stylus BT","sans-serif";
color:#2D4D5E'>NICK CATON, E.I.T.</span></b><b><span style='font-family:"Stylus BT","sans-serif";
color:#2D4D5E'><o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Calibri","sans-serif";
color:#CC9900'>PROJECT ENGINEER<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";
color:#2D4D5E'>Smith & Boucher Engineers</span><span style='font-size:7.5pt;
color:#CC9900'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";
color:#2D4D5E'>25501 west valley parkway<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";
color:#2D4D5E'>olathe ks 66061<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";
color:#2D4D5E'>direct 913 344.0036<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";
color:#2D4D5E'>fax 913 345.0617<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><a href="www.smithboucher.com"
title="blocked::www.smithboucher.com"><span style='font-size:10.0pt'>www.smithboucher.com</span></a></span><u><span
style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:blue'> </span></u><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'><o:p> </o:p></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;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>varun
kulkarni<br>
<b>Sent:</b> Tuesday, March 29, 2011 6:57 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] ASHRAE 90.1 Appendix G3.1.2.2<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal>Milda,<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>I think if you are performorming energy simulations for
the baseline, it doesnt matter what is this 25% and 15% upsizing is used for,
as it used only as much capacity it needs to satisify the loads and thermostat.
And your system size should be based on the design results and not
simulation results (that also proposed model).<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>But nevertheless I always interpret this as you said in your
first point, to cover uncertainity in building simulation. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>I also think it helps baseline to reduce its unmet load
hours.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'>Hope this helps.<o:p></o:p></p>
</div>
<div>
<div>
<div>
<p class=MsoNormal>On Tue, Mar 29, 2011 at 3:27 AM, milda margarin <<a
href="mailto:empire999@hotmail.com" target="_blank">empire999@hotmail.com</a>>
wrote:<o:p></o:p></p>
</div>
</div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
<div>
<div>
<div>
<p class=MsoNormal><span style='font-family:"Tahoma","sans-serif";color:#2A2A2A'>hi
, I already submitted this question but there were no responses so I'd like to
try again: <o:p></o:p></span></p>
<div>
<p class=MsoNormal style='line-height:12.75pt'><span style='font-family:"Tahoma","sans-serif";
color:#2A2A2A'> could somebody share some insight to the ASHRAE
90.1 Appendix G3.1.2.2 point regarding heating and cooling equipment sizing
based on building energy simulations. It is stated that the equipment should be
oversized by a factor of 1.25 for heating and 1.15 for cooling. Are these
"safety factors" based on the uncertainty associated with
building energy simulations or a requirement that makes sure that the
system can respond quickly enough during startup? Why are there different
factors applied for heating and cooling?<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='line-height:12.75pt'><span style='font-family:"Tahoma","sans-serif";
color:#2A2A2A'>thanks!<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='line-height:12.75pt'><span style='font-family:"Tahoma","sans-serif";
color:#2A2A2A'>Milda<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Tahoma","sans-serif";color:#2A2A2A'><o:p> </o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'>_______________________________________________<br>
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</blockquote>
</div>
<p class=MsoNormal><br>
<br clear=all>
<br>
-- <o:p></o:p></p>
<p style='margin:0in;margin-bottom:.0001pt'><a
name="12f01744a223be51_SafeHtmlFilter__MailAut"><span style='font-family:"Calibri","sans-serif"'>Thanks
and Best Regards,</span></a><o:p></o:p></p>
<p style='margin:0in;margin-bottom:.0001pt'><span style='font-family:"Calibri","sans-serif"'> </span><o:p></o:p></p>
<p style='margin:0in;margin-bottom:.0001pt'><span style='font-family:"Calibri","sans-serif"'>Sincerely,</span><o:p></o:p></p>
<p style='margin:0in;margin-bottom:.0001pt'><span style='font-family:"Calibri","sans-serif"'>Varun
Kulkarni , M.S. , EIT</span><o:p></o:p></p>
<p style='margin:0in;margin-bottom:.0001pt'><span style='font-family:"Calibri","sans-serif"'>RMF
Engineering</span><o:p></o:p></p>
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