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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'>Lyle,<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'>Each zone in eQUEST will be modeled as having a single, uniform temperature each hour. In cooling mode, the return air temperature should be the thermostat setpoint from the COOL-TEMP-SCH (assuming the system can meet the loads), or a little hotter from duct/plenum heat gains. You can consider using the system COOL-CONTROL strategies to modulate supply air temperature and/or flow rate. WARMEST is the only value that resets the supply air based on zone loads.<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 think you would need CFD software if you wanted to optimize data center HVAC design.<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'>My approach in eQUEST would be to model this as I would any other system – entering known system capacities, flow rates etc., and entering the expected equipment loads into the space. (My experience with a few server rooms is that data center equipment loads are nearly constant 24/7/365. I’d be interested to hear others’ experiences.) Even if the actual data center is controlled by hot aisle temperature instead of a wall-mounted thermostat, I would create the thermostat schedule based on a typical data center room setpoint, such as 75°F.<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'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Bill<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='color:#1F497D'><img width=496 height=123 id="Picture_x0020_1" src="cid:image001.jpg@01CC108C.529760A0" alt="Signature in jpg form"><o:p></o:p></span></p></div><p class=MsoNormal><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"'> equest-users-bounces@lists.onebuilding.org [mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Lyle Keck<br><b>Sent:</b> Wednesday, May 11, 2011 7:46 PM<br><b>To:</b> equest-users@lists.onebuilding.org<br><b>Subject:</b> [Equest-users] Return Air Reset Control<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Does anyone have experience modeling return air temperature reset in equest? <o:p></o:p></p><p class=MsoNormal>I am modeling a data center that resets the supply airflow based on a max return air temperature of 95 degF coming off the hot server aisles.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I searched the archives and the only thread I found on this topic did not have any useful modeling input or guidelines. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Any experience or suggestions are appreciated. Thank you for your time, <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><table class=MsoNormalTable border=0 cellpadding=0 width=172 style='width:129.15pt'><tr><td width=168 valign=top style='width:126.15pt;padding:.75pt .75pt .75pt .75pt'><p class=MsoNormal style='mso-margin-top-alt:auto;margin-bottom:12.0pt'><b><span style='font-size:10.0pt;color:#660000;text-transform:uppercase'>Lyle Keck</span></b><b><span style='font-size:9.0pt;color:#333333'> </span></b><span style='font-size:9.0pt;color:#333333'><o:p></o:p></span></p></td></tr></table><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>