Kristy,<br>Is the cool control in the PVAVS system set to constant (the default)? If the answer is yes, you are always cooling 100% of the supply air to the MIN-S-T unless cooling is scheduled off. Of course this will require substantially more cooling and reheat then a PSZ system that cools to the temp required by the control zone. I am not sure if you are comparing apples to apples.<br>
DW<br><br><div class="gmail_quote">On Tue, Jan 17, 2012 at 6:20 PM, Dahlstrom, Aaron <span dir="ltr"><<a href="mailto:ADahlstrom@in-posse.com">ADahlstrom@in-posse.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div link="blue" vlink="purple" lang="EN-US"><div><p class="MsoNormal"><span style="font-size:12pt">Kristy- <u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><p class="MsoNormal">
<span style="font-size:12pt">Did you try to use the “WASTE-HEAT-USE” feature of the PSZ system for humidity control?<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><p class="MsoNormal">
<img src="" width="480" height="301"><span style="font-size:12pt"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:12pt">I’ve had success using this feature to achieve the desired space humidity conditions with 100% OA units.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:12pt">I can’t remember whether its energy performance is appropriate, but I did verify with hourly reports that the zones in question had accurate humidity control.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:12pt">I remember having a hard time finding this feature – several late nights with the DOE-2 dictionary – but I eventually found the documentation on Vol 2 – Dictionary – pp398-399 and pp416-417.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:12pt"><u></u> <u></u></span></p><div><p class="MsoNormal" style="line-height:150%"><b><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray">Aaron Dahlstrom , PE, LEED® AP</span></b><u></u><u></u></p>
<p class="MsoNormal" style="line-height:150%"><b><span style="font-family:"AvantGarde Bk BT","sans-serif";color:rgb(23,54,93)">In P</span></b><b><span style="font-family:"AvantGarde Bk BT","sans-serif";color:rgb(97,148,40)">o</span></b><b><span style="font-family:"AvantGarde Bk BT","sans-serif";color:rgb(23,54,93)">sse</span></b><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray"> – </span><span style="font-size:8pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray">A subsidiary of</span><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray"> </span><b><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:rgb(204,0,0)">AKF</span></b><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray">| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102 </span><u></u><u></u></p>
<p class="MsoNormal" style="line-height:150%"><span style="font-size:9pt;line-height:150%;font-family:"Verdana","sans-serif";color:gray">d: <a href="tel:215-282-6753" value="+12152826753" target="_blank">215-282-6753</a>| m: <a href="tel:267-507-5470" value="+12675075470" target="_blank">267-507-5470</a>| In Posse: <a href="tel:215-282-6800" value="+12152826800" target="_blank">215-282-6800</a>| AKF: <a href="tel:215-735-7290" value="+12157357290" target="_blank">215-735-7290</a></span><u></u><u></u></p>
<p class="MsoNormal" style><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:gray">e: <a href="mailto:ADahlstrom@in-posse.com" target="_blank">ADahlstrom@in-posse.com</a> | in posse web: <a href="http://www.in-posse.com/" target="_blank">www.in-posse.com</a> | akf web: <a href="http://www.akfgroup.com/" target="_blank">www.akfgroup.com</a></span><u></u><u></u></p>
<p class="MsoNormal" style><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:gray"> </span><u></u><u></u></p><p class="MsoNormal" style><span style="font-size:9pt;font-family:"Verdana","sans-serif";color:gray"> </span><u></u><u></u></p>
</div><p class="MsoNormal"><span style="font-size:9pt;font-family:"Times New Roman","serif";color:gray"> </span><span style="font-size:12pt"><u></u><u></u></span></p><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(181,196,223) -moz-use-text-color -moz-use-text-color;padding:3pt 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10pt;font-family:"Tahoma","sans-serif""> <a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Walson, Kristy<br>
<b>Sent:</b> Tuesday, January 17, 2012 2:47 PM<br><b>To:</b> '<a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a>'<br><b>Subject:</b> [Equest-users] Lesson Learned: Single Zone Packaged DX vs. Packaged VAV system types<u></u><u></u></span></p>
</div></div><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Hi all,<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">I just wanted to share a lesson learned that I ran across recently while using Equest. Here are the pertinent specs for the building:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p><u></u><span style="font-family:Symbol"><span>·<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Proposed Case<u></u><u></u></p><p style="margin-left:1in">
<u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>65,000 sq ft of laboratory (with ac/hr requirements)<u></u><u></u></p><p style="margin-left:1in">
<u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Cooling is provided by a chilled water district plant<u></u><u></u></p><p style="margin-left:1in">
<u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Heating is provided by a district steam boiler plant<u></u><u></u></p><p style="margin-left:1in">
<u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>100% outdoor air<u></u><u></u></p><p style="margin-left:1in"><u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Humidity control is being utilized<u></u><u></u></p>
<p><u></u><span style="font-family:Symbol"><span>·<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Baseline<u></u><u></u></p><p style="margin-left:1in"><u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Per G3.1.1 Exception (c), baseline system type is #3, Packaged DX, Constant Volume, Fossil Fuel Furnace<u></u><u></u></p>
<p style="margin-left:1in"><u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Humidity control is included because it’s in the design case (ASHRAE 90.1-2007 Table G3.1 Part 1.b)<br>
<span style="color:rgb(31,73,125)"><img src="" alt="cid:image002.png@01CCD519.AEAE29D0" width="756" border="0" height="338"></span><u></u><u></u></p><p style="margin-left:1in"><u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>100% outdoor air, or a percentage to match the proposed<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Because the ASHRAE baseline system was #3, I used the Equest system type “Packaged Single Zone” for the baseline model and then proceeded to pull my hair out for a day because the baseline model was performing better than the proposed. Then I decided to try changing the baseline system type to “Packaged VAV” and setting the fan control to “Constant” with the minimum flow ratio set to “1”, in order to force it to still be a constant volume system. The first thing I noticed after <i>only</i> changing the system type was that the cooling energy almost doubled. The upshot is the following, for these Equest system types:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p><u></u><span style="font-family:Symbol"><span>·<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Packaged Single Zone<u></u><u></u></p><p style="margin-right:0in;margin-bottom:12pt;margin-left:1in">
<u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>When you add reheat in order to control humidity, the software shows an increase for the heating energy, but does not show an increase in cooling energy. Cooling energy should also increase because it now has additional heat due to reheat to overcome. The place to verify humidity control is the <b>SS-N report</b>, which showed that humidity was not being controlled, despite the fact that I had set the maximum humidity to 60% in the inputs.<u></u><u></u></p>
<p><u></u><span style="font-family:Symbol"><span>·<span style="font:7pt "Times New Roman""> </span></span></span><u></u>Packaged VAV<u></u><u></u></p><p style="margin-left:1in"><u></u><span style="font-family:"Courier New""><span>o<span style="font:7pt "Times New Roman""> </span></span></span><u></u>When you add reheat, the software shows an increase in both heating and cooling energy. <b><u>This is correct</u></b>. Otherwise, your baseline building will always perform better than the proposed. Again, verify that humidity is being controlled in the <b>SS-N report</b>.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal"><b><u><span style="background:none repeat scroll 0% 0% yellow">LESSON LEARNED</span></u><span style="background:none repeat scroll 0% 0% yellow">: Always use the Packaged VAV system type in Equest when modeling DX equipment. </span></b><span style="background:none repeat scroll 0% 0% yellow"> If you have a constant volume system, just adjust the fan control to be “Constant” and the minimum airflow ratio to be “1”.</span> <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">I hope this makes sense. Feel free to comment if you’ve had experience with this. Thanks!<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">
<b><span style="font-family:"Century Gothic","sans-serif"">Kristy M. Walson, PE, LEED AP BD+C, BEMP<u></u><u></u></span></b></p><p class="MsoNormal"><i><span style="font-size:10pt;font-family:"Century Gothic","sans-serif";color:rgb(51,51,51)">Associate / Sustainability Consultant<u></u><u></u></span></i></p>
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