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<p>This is an oft-repeated question, and an important one that I
would like to elaborate.</p>
<p>DOE-2, the simulation engine behind eQUEST, simulates the
building in steps.</p>
<p> In the first LOADS step, it calculates the heat flows in and out
of each zone at a user-defined temperature (default is 70F). These
heat flows are what appears in the eQUEST output as "Building
loads". <br>
</p>
<p>In the second SYSTEMS step, it simulates the HVAC system and
controls to derive the actual temperature of the zones, with the
heating or cooling input by the HVAC system reported in the eQUEST
output as the Building - HVAC".</p>
<p>These two "loads" are very distinct. In fact, I rarely look at
the building loads except for debugging an input file. Several
things to remember: <br>
</p>
<p>1. The Building Load (BL) contains information for each building
component (walls, roofs, lighting, infiltration, etc.) because
those are all individual heat flow paths that are simply added
together to get the BL for the space or building. <br>
</p>
<p>2. The Building - HVAC (BH) does not contain any of that because
at this step DOE-2 is just using the total Space BL (SBL) in doing
its simulation (note that in DOE-2 terminology, it's called a
"space" in Loads and a "zone" in Systems). Furthermore, since
DOE-2 derives the actual zone temperature in Systems, the SBL has
to be adjusted, making it impossible to extract the component
loads unless one does "reverse engineering" on the temperature
difference, but would always be approximate due to thermal lag,
thermostat deadband, etc. (I can talk for days about extracting
component-level loads from DOE-2 which I had to do for several
DOE-2 projects back in the 1990s).<br>
</p>
<p>3. Natural or window ventilation is considered a Systems
operation in DOE-2, so any effects from that will not appear in
the BL, but only in the BH.</p>
<p>So, I hope that clarifies why the BL is always different from the
BH!</p>
<p>Joe <br>
</p>
<p>Joe Huang</p>
<pre class="moz-signature" cols="90">Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
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
"building energy simulations at your fingertips"</pre>
<div class="moz-cite-prefix">On 3/11/2020 12:49 AM, Konstantina
Kalliakoudi via Equest-users wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAEtzSjgoQ4Uv_BVOqp62fzTDbgDa-fe4OJQqB0zDDjF4TMAkQA@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div><img
src="cid:part3.C3EF75F5.0B2EAF64@whiteboxtechnologies.com"
alt="image.png" class="" width="542" height="338"><br>
</div>
<div><br>
</div>
<div>Dear equest users,</div>
<div>I generated hourly report blocks looking for the loads.</div>
<div>I saw that there are two options:</div>
<div>1. "Building Loads" which as far I understood contains
losses, gains etc....</div>
<div>2. "Building - HVAC" - Coils - losses&gains
at te beginning I believed that it cantrained : The Loads from
the fresh air + "Building Loads". So in order to test that I
made zero the fresh air at my AHUs. I was expecting that now
the
"Building - HVAC" would be equal with
"Building Loads". But still there is a difference.
"Building - HVAC" is higher almost 50% than
"Building Loads".</div>
<div><br>
</div>
<div>Any Ideas or Comments about what
"Building - HVAC" contains more than
"Building Loads"?</div>
<div><br>
</div>
<div>Thank you for your help</div>
<div><br>
</div>
<div>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US">Konstantina Kalliakoudi</span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US">Mechanical Engineer,M.Sc., LEED AP</span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US">KHM</span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US">Filolaou 28, Ilioupoli, Athens, Greece</span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US">Tel. 0030 210 99 69 680</span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"><span
lang="EN-US"><a href="http://www.khmoe.gr"
style="color:rgb(5,99,193)" moz-do-not-send="true">www.khmoe.gr</a></span></p>
<p class="MsoNormal" style="margin:0cm 0cm
0.0001pt;font-size:11pt;font-family:Calibri,sans-serif"> </p>
</div>
</div>
<br>
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</blockquote>
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