<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman","serif";
color:black;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:"Consolas","serif";
color:black;}
span.EmailStyle20
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Qinpeng,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Normal PTAC equipment does not ever have an economizer, so the E+ object does not allow it.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you really need to model a DX cooling system with economizer, construct an E+ air loop with equivalent components for the fan, DX coil, supplemental heat, etc.<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 align=center style='text-align:center'><b><span style='font-size:11.0pt;font-family:"Arial","sans-serif";color:#0A3782'>James V Dirkes II, PE, BEMP, LEED AP</span></b><b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#3434F4'><br></span></b><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><a href="http://www.buildingperformanceteam.com/"><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#BFBFBF'>www.buildingperformanceteam.com</span></b></a></span><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#BFBFBF'> <br></span></b><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#548DD4'>Energy Analysis, Commissioning & Training Services</span></b><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#778188'><br></span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#778188'>1631 Acacia Drive, Grand Rapids, MI 49504</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#778188'> USA</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#778188'><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'> bldg-sim-bounces@lists.onebuilding.org [mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Joe Huang<br><b>Sent:</b> Friday, June 07, 2013 3:39 PM<br><b>To:</b> bldg-sim@lists.onebuilding.org<br><b>Subject:</b> Re: [Bldg-sim] Modeling PTAC system with economizer (E+)<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Qinpeng,<br><br>You might get responses to your question on the EnergyPlus_Support bulletin board than on BLDG-SIM. <br><br>Joe<br><br><o:p></o:p></p><pre>Joe Huang<o:p></o:p></pre><pre>White Box Technologies, Inc.<o:p></o:p></pre><pre>346 Rheem Blvd., Suite 108D<o:p></o:p></pre><pre>Moraga CA 94556<o:p></o:p></pre><pre><a href="mailto:yjhuang@whiteboxtechnologies.com">yjhuang@whiteboxtechnologies.com</a><o:p></o:p></pre><pre><a href="http://www.whiteboxtechnologies.com">www.whiteboxtechnologies.com</a><o:p></o:p></pre><pre>(o) (925)388-0265<o:p></o:p></pre><pre>(c) (510)928-2683<o:p></o:p></pre><pre>"building energy simulations at your fingertips"<o:p></o:p></pre><p class=MsoNormal><br>On 6/6/2013 1:26 PM, Qinpeng Wang wrote: <o:p></o:p></p><p class=MsoNormal>Hi, all, <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'm trying to model a PTAC system with economizer within E+ environment. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>The specification of the system is:<o:p></o:p></p></div><div><p>The OA economizer here is to provide "free" cooling during times of cool ambient conditions. The amount of outside air taken into the building will vary between the design percentage and the maximum percentage. And the design percentage of OA of the system is not defined as related to occupancy or floor area but 25% of total supply air.<o:p></o:p></p><p>I read the I/O reference about Controller:OutdoorAir, but it seems:<o:p></o:p></p><p>"If all the limits are satisfied, the outdoor air controller does the following for cycling fan systems: the outdoor air flow rate is set to the maximum when the fan cycles on. If the limits are not satisfied, the outdoor air flow rate is at the minimum when the fan cycles on."<o:p></o:p></p><p>The problem is it's either minimum or maximum instead of modulating according to outdoor and return air condition?<o:p></o:p></p><p>Does anyone have suggestions on this? Help greatly appreciated.<o:p></o:p></p><p>Do I have to go to EMS for this control scheme?<o:p></o:p></p><p>Best,<o:p></o:p></p><p>Qinpeng<br clear=all><o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <o:p></o:p></p><p><span style='color:#1F497D'>Qinpeng Wang, PhD Student</span><o:p></o:p></p><p><span style='color:#1F497D'>College of Architecture</span><o:p></o:p></p><p><span style='color:#1F497D'>Georgia Institute of Technology</span><o:p></o:p></p><p><span style='color:#1F497D'>Atlanta, GA 30332-0155</span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>Bldg-sim mailing list<o:p></o:p></pre><pre><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a><o:p></o:p></pre><pre>To unsubscribe from this mailing list send a blank message to <a href="mailto:BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG">BLDG-SIM-UNSUBSCRIBE@ONEBUILDING.ORG</a><o:p></o:p></pre></div></body></html>