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</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'>Neeraj, it is in fact the contrary. <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'>ASHRAE 90.1-2007 Appendix G requires you to model Baseline Airflow Rate using a 20-degree F temperature difference between the supply air and room air temperatures. Therefore, if your room set point is 75F for cooling, set your cooling leaving air temperature to 55F and vice versa for heating; 72F heating set point requires a 92F leaving air temperature. This establishes your CFM airflow within the model. Do not vary these to adjust unmet hours.<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'>If you have unmet heating or cooling hours (over 300 or greater than 50 between baseline and proposed), you may incrementally adjust the baseline cooling and heating capacities (originally oversized 15% and 25% respectively) accordingly to reduce the overall unmet hours (below 300) or the difference between baseline and proposed (within 50).<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'>Before taking this step, be sure to look at your thermostat drift points. If the cooling set point is 75, but the cooling drift point is 84, when the space is unoccupied this would allow the space to move toward 84 degrees. When the space becomes occupied and the simulation tries to cool to 75, the system will not be able to achieve this within the allotted time (1 hour) and you will have an unmet cooling hour. <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'>There are some changes to ASHRAE 90.1-2010 that will effect unmet hours, but for the time being, if you are modeling a project using 2007 or 2004, this method should help you eliminate the unmet hours.<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'>Regards,<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><b><span style='font-size:8.0pt;font-family:"Verdana","sans-serif"'>Michael M. Collarin, EIT, LEED AP BD+C </span></b><b><span style='font-size:7.0pt;font-family:"Verdana","sans-serif";color:green'>|</span></b><b><span style='font-size:7.0pt;font-family:"Calibri","sans-serif";color:green'> </span></b><b><span style='font-size:7.0pt;font-family:"Verdana","sans-serif";color:green'>Elm Engineering, Inc. | 212 S Tryon St | Suite 1375 | Charlotte, NC 28281</span></b><b><span style='font-size:7.0pt;font-family:"Arial","sans-serif";color:green'><o:p></o:p></span></b></p><p class=MsoNormal><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";color:green;letter-spacing:.9pt'>PHONE 704-335-0396 Ext. 108</span><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";color:green'>|<b> </b>FAX 704-335-0399<b> </b>|</span><b><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";color:gray'> </span></b><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";color:gray'><a href="http://www.elmengr.com/" title="blocked::http://www.elmengr.com/"><span style='font-family:"Arial","sans-serif"'>www.elmengr.com</span></a></span><span style='color:#1F497D'><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'> Nearedge [mailto:near_ej@yahoo.com] <br><b>Sent:</b> Friday, November 12, 2010 12:51 AM<br><b>To:</b> cjaigath@yahoo.com<br><b>Cc:</b> bldg-sim@lists.onebuilding.org<br><b>Subject:</b> Re: [Bldg-sim] Adjusting Capacity for Unmet Cooling<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hello Jaigath,<br>Using the performance rating method (PRM), in my experience it is usually an issue of low supply CFM.<br>Correct me if I am wrong but on the contrary I think that ASHARE baseline PRM fixes the cooling and heating capacities to 1.15 and 1.25 respectively and the user is allowed to bump up the supply CFM in increments if necessary.<br>I have a feeling that the issue of unmet load hours has been discussed many times before -- so, the archives will be a good resource as well.<br>Best,<br>Neeraj</span><o:p></o:p></p><div><p class=MsoNormal><span class=spelle><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Neeraj</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <span class=spelle>Kapoor</span><br>t: +91.99581.70018</span><o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><span class=grame><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>e</span></span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>: <span class=spelle>neeraj</span>[at]<span class=spelle>kalpakrit</span>[dot]com<br><span class=spelle>Kalpakrit</span> Sustainable Environments Pvt. Ltd.<br><a href="http://www.kalpakrit.com">www.kalpakrit.com</a></span><o:p></o:p></p><table class=MsoNormalTable border=0 cellpadding=0 width=405 style='width:303.75pt'><tr><td valign=top style='padding:1.5pt 1.5pt 1.5pt 1.5pt'><p class=MsoNormal><u><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Office Address</span></u><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>:<br>610-A <span class=spelle>Udyog</span> <span class=spelle>Vihar</span>, Phase-5,<br><span class=spelle>Gurgaon</span>, Haryana - 122016<br>t: +91.124.430.9490/ 1/ 2<br>f: +91.124.430.9493</span><o:p></o:p></p></td><td valign=top style='padding:1.5pt 1.5pt 1.5pt 1.5pt'><p class=MsoNormal><u><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Registered Address</span></u><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>:<br>101 <span class=spelle>Anupam</span> Apartments,<br><span class=spelle>Mehrauli-Badarpur</span> Road,<br>New Delhi - 110068</span><o:p></o:p></p></td></tr></table><p class=MsoNormal> <o:p></o:p></p></div><p class=MsoNormal>On 11-11-2010 10:30, Jaigath Chandraprakash wrote: <o:p></o:p></p><div><div><p class=MsoNormal>Hello All,<o:p></o:p></p></div><div><p class=MsoNormal>I would like to know how other increase their baseline capacity when they have unmet load. I have a PSZHP system and in one system, I got more than 400 hrs unmet load. I usually just increase the TR cooling capacity until I get a lower unmet load but in this case, I think the unmet load is due to low supply cfm. Is it ok to adjust also the supply fan cfm? I am thinking that G3.1.2.2 only requires me to adjust only the cooling capacity. Do others adjust both cfm and cooling load?<o:p></o:p></p></div><div><p class=MsoNormal>Thanks,<o:p></o:p></p></div><div><p class=MsoNormal>Jaigath<o:p></o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body>
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