<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"><meta name="Generator" content="Microsoft Word 12 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"MS Mincho";
panose-1:2 2 6 9 4 2 5 8 3 4;}
@font-face
{font-family:"MS Mincho";
panose-1:2 2 6 9 4 2 5 8 3 4;}
@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:"Stylus BT";
panose-1:2 14 4 2 2 2 6 2 3 4;}
@font-face
{font-family:"\@MS Mincho";
panose-1:2 2 6 9 4 2 5 8 3 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
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.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";}
span.EmailStyle20
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle21
{mso-style-type:personal-reply;
color:black;}
.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;}
/* List Definitions */
@list l0
{mso-list-id:1854105544;
mso-list-type:hybrid;
mso-list-template-ids:-284501316 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;}
@list l0:level1
{mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level2
{mso-level-tab-stop:1.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level3
{mso-level-tab-stop:1.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level4
{mso-level-tab-stop:2.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level5
{mso-level-tab-stop:2.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level6
{mso-level-tab-stop:3.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level7
{mso-level-tab-stop:3.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level8
{mso-level-tab-stop:4.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l0:level9
{mso-level-tab-stop:4.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1
{mso-list-id:1979799056;
mso-list-type:hybrid;
mso-list-template-ids:-1721436140 -42286368 67698691 67698693 67698689 67698691 67698693 67698689 67698691 67698693;}
@list l1:level1
{mso-level-start-at:0;
mso-level-number-format:bullet;
mso-level-text:-;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-.25in;
font-family:"Calibri","sans-serif";
mso-fareast-font-family:"MS Mincho";
mso-bidi-font-family:"Times New Roman";}
@list l1:level2
{mso-level-tab-stop:1.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level3
{mso-level-tab-stop:1.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level4
{mso-level-tab-stop:2.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level5
{mso-level-tab-stop:2.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level6
{mso-level-tab-stop:3.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level7
{mso-level-tab-stop:3.5in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level8
{mso-level-tab-stop:4.0in;
mso-level-number-position:left;
text-indent:-.25in;}
@list l1:level9
{mso-level-tab-stop:4.5in;
mso-level-number-position:left;
text-indent:-.25in;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black">Although “highly-conductive” you wouldn’t necessarily assume that the space temperatures end up being identical – there is still some resistance in your example, even if very small, and the area of interface is not infinite either.</span></font></p>
<p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></p><p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black">Your last example with area/volume – the heat transfer will be limited by the size and thermal conductivity of this air wall. There are also radiant and storage effects from the other surfaces in the zone that might keep the two from being in equilibrium – that said your approach may be fine as you may not have widely differing temperatures/loads. One possible tweak might be to allocate your internal gains in these two modeled spaces to load the separately modeled HVAC systems along how you think they would actually perform in the real “two-system-one-zone” space. </span></font></p>
<p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></p><p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black">David</span></font></p>
<p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></p><div><p class="MsoNormal"><u><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></u></p>
<p class="MsoNormal"><font size="1" color="black" face="Calibri"><span style="font-size:8.0pt;color:black"> </span></font></p><p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size:11.0pt;color:#1F497D">David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, HBDP</span></font></p>
<p class="MsoNormal"><b><font size="2" color="#244061" face="Calibri"><span style="font-size:11.0pt;color:#244061;font-weight:bold">Grumman/Butkus Associates</span></font></b><font size="1" color="gray"><span style="font-size:9.0pt;color:gray"></span></font></p>
<p class="MsoNormal"><u><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></u></p>
</div><p class="MsoNormal"><font size="2" color="black" face="Calibri"><span style="font-size:11.0pt;color:black"> </span></font></p><div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt"><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><font size="2" face="Tahoma"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";font-weight:bold">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a> <a href="mailto:[mailto:equest-users-bounces@lists.onebuilding.org]">[mailto:equest-users-bounces@lists.onebuilding.org]</a> <b><span style="font-weight:bold">On Behalf Of </span></b>Nick Caton<br>
<b><span style="font-weight:bold">Sent:</span></b> Wednesday, January 26, 2011 11:49 AM<br><b><span style="font-weight:bold">To:</span></b> <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br>
<b><span style="font-weight:bold">Subject:</span></b> [Equest-users] What's in an Air Wall?</span></font></p></div></div><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt">Hi everyone,</span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal">
<font size="2" face="Calibri"><span style="font-size:11.0pt">A discussion on [bldg-sim] prompted me to bring up a topic that’s been bugging me in the “eQuest fundamentals” department… </span></font></p><p class="MsoNormal">
<font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt">I have a general understanding that eQuest does not fundamentally model airflow (specifically, convection of internal loads) between zones.</span></font></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">-<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>The DOE-2 entry for INT-WALL-TYPE says an internal “air” partition “ …designates a non-physical interior surface with no mass (i.e., an opening between spaces) across which convection can take place.”</p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">-<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>A wizard-generated “air” internal partition has a construction with U-factor of 2.7… very conductive.</p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">-<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font> To draw a conclusion – two zones connected with an “air” partition are “connected” thermally. In practice, the internal loads in one are “combined” with the other.</p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo2"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">-<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>This means heat in one zone should travel to the other in a rapid fashion during the hourly simulation, until the space temperatures are identical between the two.</p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt">I hope my understanding thus far is correct, because from here I have some questions that dig at what’s going on under the hood:</span></font></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo4"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">1.<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>Imagine an air partition “connects” zones A and B. These zones have separate systems and separate thermostats with different setpoints. If zone A’s thermostat wants to be much warmer than zone B, is it possible the systems will “fight” each other and cause mutual unmet hours?</p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo4"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">2.<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>In the same setup, if Zone A is identical in geometry to Zone B, but has 2x the internal/external loads, does it follow that the system for System A will handle 2x the internal loads as System B, or are they summed and applied equally to the two systems on an hourly basis? </p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo4"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">3.<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>Is the “distribution of loads behavior” affected if Systems A & B are specified with different capacities and/or airflows? </p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo4"><font size="2" face="Calibri"><span style="font-size:11.0pt"><span style="mso-list:Ignore">4.<font size="1" face="Times New Roman"><span style="font:7.0pt "Times New Roman""> </span></font></span></span></font>If one space is larger in area/volume than the other, does that affect how the collective loads are distributed to the corresponding systems?</p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt">I have “exploited” air partition behavior in the past to get around the “one system per zone” rule (need two RTU’s serving that space? Just make an imaginary air wall!). However I want to be sure before I continue this practice or advise others to do the same that there aren’t any major potential pitfalls in how the loads/systems are distributed/affected…</span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt">~Nick</span></font></p><p class="MsoNormal">
<font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p><p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"><img border="0" width="119" height="37" id="Picture_x0020_1" src="cid:image001.jpg@01CBBD50.7BEC2CE0" alt="cid:489575314@22072009-0ABB"></span></font><b><font color="#2d4d5e" face="Stylus BT"><span style="font-family:"Stylus BT","sans-serif";color:#2D4D5E;font-weight:bold"></span></font></b></p>
<p class="MsoNormal"><b><font size="2" color="#2d4d5e" face="Stylus BT"><span style="font-size:11.0pt;font-family:"Stylus BT","sans-serif";color:#2D4D5E;font-weight:bold"> </span></font></b></p><p class="MsoNormal">
<b><font size="2" color="#2d4d5e" face="Stylus BT"><span style="font-size:11.0pt;font-family:"Stylus BT","sans-serif";color:#2D4D5E;font-weight:bold">NICK CATON, E.I.T.</span></font></b><b><font size="3" color="#2d4d5e" face="Stylus BT"><span style="font-size:12.0pt;font-family:"Stylus BT","sans-serif";color:#2D4D5E;font-weight:bold"></span></font></b></p>
<p class="MsoNormal"><font size="1" color="#cc9900" face="Calibri"><span style="font-size:7.5pt;color:#CC9900">PROJECT ENGINEER</span></font></p><p class="MsoNormal"><font size="2" color="#2d4d5e" face="Calibri"><span style="font-size:10.0pt;color:#2D4D5E">Smith & Boucher Engineers</span></font><font size="1" color="#cc9900" face="Times New Roman"><span style="font-size:7.5pt;font-family:"Times New Roman","serif";color:#CC9900"></span></font></p>
<p class="MsoNormal"><font size="2" color="#2d4d5e" face="Calibri"><span style="font-size:10.0pt;color:#2D4D5E">25501 west valley parkway</span></font></p><p class="MsoNormal"><font size="2" color="#2d4d5e" face="Calibri"><span style="font-size:10.0pt;color:#2D4D5E">olathe ks 66061</span></font></p>
<p class="MsoNormal"><font size="2" color="#2d4d5e" face="Calibri"><span style="font-size:10.0pt;color:#2D4D5E">direct 913 344.0036</span></font></p><p class="MsoNormal"><font size="2" color="#2d4d5e" face="Calibri"><span style="font-size:10.0pt;color:#2D4D5E">fax 913 345.0617</span></font></p>
<p class="MsoNormal"><font size="2" color="#1f497d" face="Calibri"><span style="font-size:11.0pt;color:#1F497D"><a href="www.smithboucher.com" title="blocked::www.smithboucher.com"><font size="2"><span style="font-size:10.0pt">www.smithboucher.com</span></font></a></span></font><u><font size="2" color="blue"><span style="font-size:10.0pt;color:blue"> </span></font></u><font color="#1f497d"><span style="color:#1F497D"></span></font></p>
<p class="MsoNormal"><font size="2" face="Calibri"><span style="font-size:11.0pt"> </span></font></p></div></div></body></html>