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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D'>Regis,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I have a theory why your gas consumption goes up when you incorporate the discharge air temperature reset, but I don’t know how to get around it. Perhaps someone more familiar with the DOE-2.2 code and algorithms can chime in. I believe it has to do with the difference between <u>discharge</u> air temperature and <u>mixed</u> air temperature.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Based on the economizer examples in the DOE-2.2 documentation “Volume 3: Topics” (p. 121-124) the economizer is controlled to a <u>mixed</u> air temperature setpoint. (TAPPXX in the FORTRAN code below.)<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><img width=581 height=654 id="Picture_x0020_1" src="cid:image001.png@01CCC6D7.8A359F20"></span><span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I suspect that the economizer control is not changed by resetting the <u>discharge</u> air temperature setpoint. Perhaps the mixed air temperature setpoint is back-calculated from the discharge air temperature setpoint by subtracting the fan heat. I don’t know for sure. Raising the discharge air setpoint might be causing the heating coil to come on and warm the air from the mixed air temperature to the higher discharge air temperature. That’s my theory.<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>I have not found a way to access the mixed air temperature setpoint through eQUEST. Do any of you people more familiar with DOE-2 know of any BDL lines that could be added to the .inp file to adjust the mixed air temperature setpoint so that the economizer will not overcool? <o:p></o:p></span></p><div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>________________________________</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><ns0:PersonName><span style='color:#1F497D'>Keith Swartz</span></ns0:PersonName><span style='color:#1F497D'>, P.E., LEED AP</span></span><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><br>Energy Engineer / Senior Project Manager<br></span><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><ns0:PlaceName><span style='color:#1F497D'>Energy</span></ns0:PlaceName><span style='color:#1F497D'> </span><ns0:PlaceType><span style='color:#1F497D'>Center</span></ns0:PlaceType><span style='color:#1F497D'> of </span><ns0:place><ns0:State><span style='color:#1F497D'>Wisconsin</span><span style='color:#1F497D;font-weight:normal'><br></span><span style='font-weight:normal'></ns0:State></span></ns0:place></span></b><ns0:Street><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><ns0:address><span style='color:#1F497D'>455 Science Drive, Suite 200, </span></ns0:address></ns0:Street></span><ns0:place><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><ns0:City><span style='color:#1F497D'>Madison</span></ns0:City><span style='color:#1F497D'>, </span><ns0:State><span style='color:#1F497D'>WI</span></ns0:State><span style='color:#1F497D'> </span><ns0:PostalCode><span style='color:#1F497D'>53711<br></span></ns0:PostalCode></ns0:place></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Phone: 608.238.8276 x123<br>Fax: 608.238.0523<br><br></span><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>The Buildings Team</span></b><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><o:p></o:p></span></p></div><div><p class=MsoNormal><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Design decisions through energy, economics and emissions analysis.</span></i><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'><a href="http://www.ecw.org/Buildings">www.ecw.org/Buildings</a> <o:p></o:p></span></p></div></div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><br></span><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'><ns0:place><ns0:PlaceName><span style='color:#1F497D'>Energy</span></ns0:PlaceName><span style='color:#1F497D'> </span><ns0:PlaceType><span style='color:#1F497D'>Center</span></ns0:PlaceType><span style='color:#1F497D'> </span><ns0:PlaceType><span style='color:#1F497D'>University<br></span></ns0:PlaceType></ns0:place></span></b><i><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>Your gateway to sustainable design training and online education programs.<br></span></i><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D'><a href="http://www.ecw.org/university/" title="http://www.ecw.org/university/"><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>www.ecw.org/university/</span></a></span><span style='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"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Regis Bruant [mailto:RBruant@B2Qassociates.com] <br><b>Sent:</b> Thursday, December 29, 2011 2:36 PM<br><b>To:</b> equest-users@lists.onebuilding.org<br><b>Cc:</b> Joshua Doolittle<br><b>Subject:</b> [Equest-users] Economizer issue<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi everyone,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am trying to implement an economizer based on OA enthalpy on a baseline model that has an economizer set on OA temperature and have issue because I have an unexpected increased in gas usage on the proposed case.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The system I am working on consists of a VAV box containing a heating and cooling coil respectively attached to a Hot water loop and a chilled water loop (operating from March to October). It has terminal reheat coils at the zone level.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>-The baseline economizer system is set on Outdoor air temperature high limit of 50F because of the low discharge air temperature of 52F. <o:p></o:p></p><p class=MsoNormal>-The proposed case economizer is set on an enthalpy high limit of 23BTU (and an OA temperature high limit of arbitrarily 100F because we want the economizer to be only limited by the enthalpy). The discharge air temperature was also reset because the system will be economizing with air temperature higher than the initial discharge temperature of 52F. It was reset from 52F to 63F as the Outdoor temperature varies from 52 to 73F.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Results:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>-1<sup>st</sup> run: When running the discharge air setpoint reset based on OAT alone, we obtain substantial electrical and gas usage gain.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>-2<sup>nd</sup> run: When running the discharge air setpoint reset based on OAT + the economizer based on OA enthalpy, we obtain even higher gain in electrical consumption but a lower gas usage gain.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Results numbers: <o:p></o:p></p><p class=MsoNormal>Baseline: <o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Elec: 14,582,599 kwh<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Gas: 646,752 therms<o:p></o:p></p><p class=MsoNormal>1<sup>st</sup> run:<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Elec: 14,439,619 kwh<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Gas:587,782 therms<o:p></o:p></p><p class=MsoNormal>2nd run:<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Elec: 14,319,200kwh<o:p></o:p></p><p class=MsoNormal style='text-indent:.5in'>Gas: 607,876 therms<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I do not understand why there is a gas usage increase on the 2<sup>nd</sup> run in comparison to the 1<sup>st</sup> run. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Has anyone been through the same issue? It would be very helpful to share any kind of info.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you for your time,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><b><span style='color:#0066CC'>Regis Bruant</span></b><span style='font-size:12.0pt;font-family:"Times New Roman","serif";color:navy'><o:p></o:p></span></p><p class=MsoNormal><span style='color:#0066CC'>Intern</span><span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><b><span style='color:#0066CC'>B2Q Associates, Inc.<o:p></o:p></span></b></p><p class=MsoNormal><span style='color:#0066CC'>146 Main Street #2<o:p></o:p></span></p><p class=MsoNormal><span style='color:#0066CC'>North Andover, MA 01845<o:p></o:p></span></p><p class=MsoNormal><span style='color:#0066CC'>Office: 978.208.0609 x212</span><span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><span lang=FR style='color:#0066CC'>Fax: 978.719.6339<o:p></o:p></span></p><p class=MsoNormal><span lang=FR style='color:#0066CC'>Mobile: 978.810.1858</span><span lang=FR style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><span lang=FR style='color:#0066CC'>Email: <a href="mailto:rbruant@B2Qassociates.com">rbruant@B2Qassociates.com</a> <o:p></o:p></span></p><p class=MsoNormal><span style='color:#0066CC'><a href="http://www.b2qassociates.com/" title="http://www.b2qassociates.com/">www.b2qassociates.com</a></span><span style='color:navy'><o:p></o:p></span></p><p class=MsoNormal><span style='color:navy'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:navy'>The contents of this e-mail and any attachments are confidential and the property of the B2Q Associates, Inc. The e-mail contents are only to be used by the intended recipient of the e-mail. If you are not the intended recipient then use, disclosure, copying, distribution or reliance on the e-mail is prohibited. All professional advice from us should be obtained in writing (not e-mail).</span><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>