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Just to repeat what David and Rodrigo have already sad, DOE-2
calculates conduction loads in a two step process. In LOADS, a
constant reference temperature is specified, which DOE-2 uses to
calculate the amount of heat flow through the surfaces. This is the
LOADS loads summarized in the LS-E and LS-F reports. In SYSTEMS,
DOE-2 calculates the true temperature of the zone based on the loads
passed from LOADS, as well as the actions of the HVAC system. In
the course of this calculation, the heat flows ("loads") from LOADS
are adjusted, but this is not done surface by surface, but in total
using the so-called "Zone Conductance" times the difference between
the actual zone temperature and the reference temperature used in
LOADS. At this point, heat flows through internal walls are also
considered, using the difference between this hour's zone
temperature and the previous hour's zone temperature of the adjacent
space, e.g., the Attic or Plenum. If you are interested in this
number, I believe it can be extracted in an hourly report. <br>
<br>
In reference to Rodrigo's question, I don't see any benefit in
forcing a heat flow between the room and the attic by using
different reference temperatures. You will simply get a constant
heat flow at that temperature difference throughout the simulation.
In reality, attics are generally colder than the room in the winter
and warmer than the room in the summer, so the derived heat flow
with this temperature difference doesn't get you any closer to
reality, in my opinion.<br>
<br>
Joe<br>
<pre class="moz-signature" cols="90">Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
<a class="moz-txt-link-abbreviated" href="mailto:yjhuang@whiteboxtechnologies.com">yjhuang@whiteboxtechnologies.com</a>
<a class="moz-txt-link-freetext" href="http://weather.whiteboxtechnologies.com">http://weather.whiteboxtechnologies.com</a> for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
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</pre>
<br>
On 8/19/2013 12:05 PM, David Wood wrote:
<blockquote
cite="mid:CABpLho5cyZjqwUjHQ9vwbbo9tM7pr7nSEWCxW2w2aY3kMNCoHw@mail.gmail.com"
type="cite">
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charset=ISO-8859-1">
<div>
<div>
<div>Hi All,<br>
<br>
</div>
The LS-C report comes from the LOADS simulation portion of DOE
2.2. The plenum reference temperature used in LOADS is
adjusted in the SYSTEMS portion of the program and the loads
in the spaces adjacent to the plenum are corrected <br>
correspondingly.<br>
<br>
</div>
Dave Wood<br>
</div>
<div><br>
<br>
<div>On Thu, Aug 8, 2013 at 8:58 AM, Rodrigo Cerqueira <span><<a
moz-do-not-send="true"
href="mailto:rodrigo.cerqueira@mra.qc.ca">rodrigo.cerqueira@mra.qc.ca</a>></span>
wrote:<br>
<blockquote>
<div lang="FR-CA">
<div>
<p><span lang="EN-US">Hi, </span></p>
<p>
<span lang="EN-US">This happens because the load
calculation is made with a fixed temperature (see
picture). All the spaces, include plenum zones, have
the same temperature by default (70°F). So, all roof
load appears in the plenum spaces. To considerate
the roof load, you have to change this temperature
in plenum spaces and a part of roof load will appear
like "internal surface conduction". But I'm not sure
if this is a good practice. </span><span>Maybe
someone else has an opinion about that. </span></p>
<p><span> </span></p>
<p><span><img moz-do-not-send="true"></span><span> </span></p>
<p><span> </span></p>
<p><b><span>Rodrigo Cerqueira, </span></b><span>ing.
jr, M.Ing.<b> </b></span></p>
<p><b><span>Simulation énergétique </span></b></p>
<p><span> </span></p>
<p><span><img moz-do-not-send="true"
alt="signatureCouriel"> </span></p>
<p><span> </span></p>
<p><span> </span></p>
<p><span> </span></p>
<div>
<p><b><span lang="FR">De :</span></b><span lang="FR">
<a moz-do-not-send="true"
href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a>
[mailto:<a moz-do-not-send="true"
href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a>]
<b>De la part de</b> Bhartendu Awasthi<br>
<b>Envoyé :</b> 8 août 2013 06:35<br>
<b>À :</b> <a moz-do-not-send="true"
href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a>;
<a moz-do-not-send="true"
href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</a><br>
<b>Objet :</b> [Equest-users] Roof Conduction Load
</span></p>
</div>
<p> </p>
<div>
<p>Hi All, </p>
<div>
<p> </p>
</div>
<div>
<pre><span>I am doing an energy simulation model in eQuest. I noticed that the load through roof conduction in LS-C is zero where as in LS-B (for plenum space) it is showing some load.</span><span> </span></pre>
<pre><span> </span></pre>
<pre><span>As per my understanding this load should appear in LS-C also.</span><span> </span></pre>
<pre><span>Also, if I reduce the U value of the roof, the load through roof reduces and can be accounted in LS-B only (plenum space).</span><span> </span></pre>
<pre><span> </span></pre>
<pre><span>Refer attached LS-C and LS-B reports.</span><span> </span></pre>
<pre><span>Any help will be appreciated.</span><span> </span></pre>
<pre><span> </span></pre>
<pre><span> </span></pre>
<pre><span>Thanks & Regards</span><span> </span></pre>
<pre><span> </span></pre>
<pre><span>Bhartendu Awasthi</span><span> </span></pre>
</div>
</div>
</div>
</div>
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</blockquote>
</div>
<br>
<br>
<br>
-- <br>
<div>
<div><span><span><span></span></span><span><span></span></span><span><span>Regards,<br>
</span></span></span></div>
<div><span><span><span></span><br>
David S. Wood<br>
Principal<br>
Wood, Byk & Associates<br>
office: 610.347.0710<br>
</span></span></div>
<span><span>mobile: 610.247.1208</span></span><br>
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