<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Hi Nick,</div><div><br></div>An air wall is treated as a heat transfer surface in DOE, with a certain thermal conductivity (or U-value). It is my understanding that DOE assumes that everything is steady state; that is, the temperature in the spaces on either side of the air wall are held constant at their set points. The LOADS program will calculate the heat transfer to be Q = UA (T_warm - T1_cool) from the warmer to the cooler space. This heat transfer will show up as a constant heating load in the warmer space and a constant cooling load in the cooler space. Depending on the size of this heating/cooling load relative to the capacities of the systems, this could lead to unmet heating/cooling hours. <div><br></div><div>The size of this load will depend only on the area of the interior wall separating the two spaces, the thermal conductivity of the wall, and the difference in temperatures. The size of this load will not depend on the geometry or volume of the spaces in question, or on the internal loads in each space, etc. <div><br></div><div>If you are using an air wall to force a space to accept two systems, then I would be very careful about where the wall goes to ensure that the operation of the two systems best reflects the design intention. For example, you might want to consider how the placement of the wall separating the spaces affect the external loads that each space experiences, etc. <div><br></div><div>Cheers,</div><div>Dan</div><div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Verdana; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">—<br>Daniel Knapp, PhD, LEED® AP O+M<br><a href="mailto:danielk@arborus.ca">danielk@arborus.ca</a><br><br>Arborus Consulting<br>Energy Strategies for the Built Environment<br>www.arborus.ca<br>76 Chamberlain Avenue <br>Ottawa, ON, K1S 1V9 <br>Phone: (613) 234-7178 ext. 113<br>Fax: (613) 234-0740<br><span></span><br><br></span>
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<br><div><div>On 2011-01-26, at 12:48 PM, Nick Caton wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Verdana; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div lang="EN-US" link="blue" vlink="purple"><div class="Section1" style="page: Section1; "><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Hi everyone,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">A discussion on [bldg-sim] prompted me to bring up a topic that’s been bugging me in the “eQuest fundamentals” department… <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">I have a general understanding that eQuest does not fundamentally model airflow (specifically, convection of internal loads) between zones.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>-<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>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.”<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>-<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>A wizard-generated “air” internal partition has a construction with U-factor of 2.7… very conductive.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>-<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span> 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.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>-<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>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.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">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:<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>1.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>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?<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>2.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>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? <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>3.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>Is the “distribution of loads behavior” affected if Systems A & B are specified with different capacities and/or airflows? <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0.5in; font-size: 11pt; font-family: Calibri, sans-serif; text-indent: -0.25in; "><span>4.<span style="font: normal normal normal 7pt/normal 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span>If one space is larger in area/volume than the other, does that affect how the collective loads are distributed to the corresponding systems?<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">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…<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">~Nick<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span><image001.jpg></span><b><span style="font-family: 'Stylus BT', sans-serif; color: rgb(45, 77, 94); "><o:p></o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><b><span style="font-family: 'Stylus BT', sans-serif; color: rgb(45, 77, 94); "><o:p> </o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><b><span style="font-family: 'Stylus BT', sans-serif; color: rgb(45, 77, 94); ">NICK CATON, E.I.T.</span></b><b><span style="font-size: 12pt; font-family: 'Stylus BT', sans-serif; color: rgb(45, 77, 94); "><o:p></o:p></span></b></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 7.5pt; color: rgb(204, 153, 0); ">PROJECT ENGINEER<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; color: rgb(45, 77, 94); ">Smith & Boucher Engineers</span><span style="font-size: 7.5pt; font-family: 'Times New Roman', serif; color: rgb(204, 153, 0); "><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; color: rgb(45, 77, 94); ">25501 west valley parkway<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; color: rgb(45, 77, 94); ">olathe ks 66061<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; color: rgb(45, 77, 94); ">direct 913 344.0036<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; color: rgb(45, 77, 94); ">fax 913 345.0617<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="color: rgb(31, 73, 125); "><a href="x-msg://269/www.smithboucher.com" title="blocked::www.smithboucher.com" style="color: blue; text-decoration: underline; "><span style="font-size: 10pt; color: blue; ">www.smithboucher.com</span></a></span><u><span style="font-size: 10pt; color: blue; "></span></u><span style="color: rgb(31, 73, 125); "><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div></div>_______________________________________________<br>Equest-users mailing list<br><a href="http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org" style="color: blue; text-decoration: underline; ">http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org</a><br>To unsubscribe from this mailing list send a blank message to<span class="Apple-converted-space"> </span><a href="mailto:EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG" style="color: blue; text-decoration: underline; ">EQUEST-USERS-UNSUBSCRIBE@ONEBUILDING.ORG</a><br></div></span></blockquote></div><br></div></div></div></body></html>