<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV>If return air is via plenum then the volume connected to the return air is the same. My guess is that EQuest/2.2 does not try to do a CO2 balance and is thus working off occupant density and outdoor air (probably from mechanical systems only) so volume may be inconsequential. For large spaces with transient occupancy this could be inaccurate - codes in Australia allow us to take advantage of this large volume of unvitiated air for theatre foyers etc. If EQuest/2.2 did do a transient CO2 balance then the inaccurracies of modelling with no plenum would be limited to transient conditions which for offices would be morning, evening and lunch. In this case I gues your simulation would be slightly optimistic. I assume Steve Gates / Jeff Hirsch can clarify anything that isn't stated in the 2.2 Dictionary. </DIV><DIV>Regards,</DIV><DIV>Graham</DIV><DIV><DIV>On 17/07/2007, at 3:06 AM, Lynn Qualmann wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Arial; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV dir="ltr" align="left"><SPAN class="166245316-16072007"><FONT face="Arial" color="#0000ff" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">Thanks to everyone who responded to the threads that came from the original question. With respect to the note immediately below, how is the demand for outside air determined when DCV is modeled in eQuest? I was assuming the inputs would be the number of occupants (and their activity levels) and the volume of the space. If deleted plenum volumes are re-assigned to occupied spaces, the CO2 concentration (and presumably OA fraction) should clearly be reduced in a real-life DCV situation. Does the eQuest model of DCV take this into account or is it more simplified?</SPAN></FONT></SPAN></DIV><DIV><SPAN class="166245316-16072007"><FONT face="Arial" color="#0000ff" size="2"></FONT></SPAN> </DIV><DIV><SPAN class="166245316-16072007"><FONT face="Arial" color="#0000ff" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; "></SPAN><DIV align="left"><FONT size="2"><FONT face="Arial"><STRONG style="color: rgb(0, 0, 255); font-size: 13px; font-weight: bold; text-align: -khtml-left; "><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; font-weight: bold; text-align: -khtml-left; ">R. Lynn Qualmann, P.E</SPAN></STRONG><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">.</SPAN></FONT></FONT></DIV><DIV align="left"><FONT face="Arial" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">SBW Consulting, Inc.</SPAN></FONT></DIV><DIV align="left"><FONT face="Arial" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">2820 Northup Way #230</SPAN></FONT></DIV><DIV align="left"><FONT face="Arial" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">Bellevue, WA 98004</SPAN></FONT></DIV><DIV align="left"><FONT face="Arial" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); font-size: 13px; text-align: -khtml-left; ">Phone: (425) 827-0330</SPAN></FONT></DIV><DIV align="left"><FONT face="Arial" size="2"><SPAN class="Apple-style-span" style="color: rgb(0, 0, 255); 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text-align: -khtml-left; "> BLDG-SIM@gard.com [<A href="mailto:BLDG-SIM@gard.com">mailto:BLDG-SIM@gard.com</A>] </SPAN><B style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; "><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; ">On Behalf Of </SPAN></B><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; ">David S Eldridge</SPAN><BR style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "><B style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; "><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; ">Sent:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "> Monday, July 16, 2007 8:13 AM</SPAN><BR style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "><B style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; "><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; ">To:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "> <A href="mailto:BLDG-SIM@gard.com">BLDG-SIM@gard.com</A></SPAN><BR style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "><B style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; "><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; font-weight: bold; text-align: -khtml-left; ">Subject:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "> [BLDG-SIM] Oh, what a tangled web we weave...</SPAN><BR style="font-family: Tahoma; font-size: 13px; text-align: -khtml-left; "></FONT><BR style="text-align: -khtml-left; "></DIV><DIV></DIV><DIV class="Section1"><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; ">John, that is a good point if your program is modeling the CO2 concentration explicitly.</SPAN><O:P style="font-family: Times New Roman; "></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; ">If you (or simulation program) are using the scheduled quantity of people as the surrogate for CO2 measurements then it would be the same amount of OA with or without plenums.</SPAN><O:P style="font-family: Times New Roman; "></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; ">(How ironic is that? Using number of people in the model as the surrogate for CO2 measurements…which in the real building is the surrogate for the number of people…)</SPAN><O:P style="font-family: Times New Roman; "></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; ">David</SPAN><O:P style="font-family: Times New Roman; "></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></SPAN></P><P class="MsoNormal"><SPAN style="COLOR: black; font-family: Times New Roman; "><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></SPAN></P><DIV style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: medium none; PADDING-LEFT: 4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: blue 1.5pt solid; PADDING-TOP: 0in; BORDER-BOTTOM: medium none"><DIV><DIV style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; PADDING-LEFT: 0in; PADDING-BOTTOM: 0in; BORDER-LEFT: medium none; PADDING-TOP: 3pt; BORDER-BOTTOM: medium none"><P class="MsoNormal"><B style="font-family: Times New Roman; font-weight: bold; "><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: ; font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; " tahoma?,?sans-serif??=""><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; ">From:</SPAN></SPAN></B><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: ; font-family: Times New Roman; font-size: 13.3333px; " tahoma?,?sans-serif??=""><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; "> BLDG-SIM@gard.com [<A href="mailto:BLDG-SIM@gard.com">mailto:BLDG-SIM@gard.com</A>] </SPAN><B style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; ">On Behalf Of </SPAN></B><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; ">Peterson, John</SPAN><BR style="font-family: Times New Roman; font-size: 13.3333px; "><B style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; ">Sent:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; "> Friday, July 13, 2007 8:05 AM</SPAN><BR style="font-family: Times New Roman; font-size: 13.3333px; "><B style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; ">To:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; "> <A href="mailto:BLDG-SIM@gard.com">BLDG-SIM@gard.com</A></SPAN><BR style="font-family: Times New Roman; font-size: 13.3333px; "><B style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; font-weight: bold; ">Subject:</SPAN></B><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 13.3333px; "> [BLDG-SIM] Oh, what a tangled web we weave...</SPAN><O:P style="font-family: Times New Roman; font-size: 13.3333px; "></O:P></SPAN></P></DIV></DIV><P class="MsoNormal"><O:P style="font-family: Times New Roman; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; "> </SPAN></O:P></P><P class="MsoNormal"><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: ; font-family: Times New Roman; font-size: 14.6667px; " color:blue?="" garamond?,?serif?;=""><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 14.6667px; ">The plenums subtract from the total room volume. If the return is ducted, this makes a large difference. Also while the plenum & room may have the same or nearly the same temp/humidity, ventilation rates for the room might be calculated based on a CO2 level difference. The CO2 calculation is based on the room volume, which relates directly with OA needed, and hence the energy to condition that OA. The plenum can mean a big difference in room volume flows when extrapolated across an entire building. </SPAN><O:P style="font-family: Times New Roman; font-size: 14.6667px; "></O:P></SPAN></P><P class="MsoNormal"><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: ; font-family: Times New Roman; font-size: 14.6667px; " color:blue?="" garamond?,?serif?;=""><O:P style="font-family: Times New Roman; font-size: 14.6667px; "><SPAN class="Apple-style-span" style="font-family: Times New Roman; font-size: 14.6667px; "> </SPAN></O:P></SPAN></P><DIV><TABLE class="MsoNormalTable" style="WIDTH: 225pt; border-spacing: 2px 2px; " cellpadding="0" width="300" border="0"><TBODY style="border-spacing: 2px 2px; "><TR style="border-spacing: 2px 2px; "><TD style="PADDING-RIGHT: 0.75pt; PADDING-LEFT: 0.75pt; PADDING-BOTTOM: 0.75pt; WIDTH: 98.66%; PADDING-TOP: 0.75pt; border-spacing: 2px 2px; " width="98%" colspan="2"><P class="MsoNormal"><SPAN style="FONT-SIZE: 10pt; COLOR: blue; border-spacing: 2px 2px; color: rgb(0, 0, 255); font-family: Times New Roman; font-size: 13.3333px; "><SPAN class="Apple-style-span" style="border-spacing: 2px 2px; color: rgb(0, 0, 255); font-family: Times New Roman; font-size: 13.3333px; ">John Peterson, PE, LEED AP</SPAN><O:P style="border-spacing: 2px 2px; color: rgb(0, 0, 255); font-family: Times New Roman; font-size: 13.3333px; "></O:P></SPAN></P></TD></TR><TR style="border-spacing: 2px 2px; "><TD style="PADDING-RIGHT: 0.75pt; PADDING-LEFT: 0.75pt; PADDING-BOTTOM: 0.75pt; WIDTH: 98.66%; PADDING-TOP: 0.75pt; border-spacing: 2px 2px; " width="98%" colspan="2"><P class="MsoNormal"><SPAN style="FONT-SIZE: 10pt; COLOR: blue; border-spacing: 2px 2px; color: rgb(0, 0, 255); font-family: Times New Roman; font-size: 13.3333px; "><SPAN class="Apple-style-span" style="border-spacing: 2px 2px; color: rgb(0, 0, 255); font-family: Times New Roman; font-size: 13.3333px; ">625 N. 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