I agree with Brian. I have done similar studies and found that in certain climates the savings offset. However, 3% sounds a little low, especially with 30% glass.<div><br></div><div>There are other issues that come into play as well with VAV systems. What probably is happening is that the airflows are different and the VAV minimums are affected (or perhaps they are identical which could also cause a lack of savings).</div>
<div><br></div><div>You may want to compare using the sim file, the number of hours running at VAV minimum, since the better glass may actually be eliminating "free reheat" during certain times of the year. I have seen this often. Make sure all of your design airflows are the same by locking them into place in both runs (since I'm guessing you are not changing the fans).</div>
<div><br></div><div>Bob Fassbender</div><div>Cosmo Logic LLC</div><div>Energy-Models.com<br><br><div class="gmail_quote">On Mon, Nov 8, 2010 at 4:02 PM, Wolfe, Brian <span dir="ltr"><<a href="mailto:bwolfe@hksinc.com">bwolfe@hksinc.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="EN-US" link="blue" vlink="purple">
<div>
<p class="MsoNormal"><span style="color:#1F497D">I couldn’t get it to open
to check, but since there’s a total of 3% change, you might check the difference
between space cooling and heating. The difference might be counteracting
each other enough to reduce the benefits that you thought you’d
see. The location and internal loads might have some affect as well.</span></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span></p>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">BRIAN J. WOLFE, CDT, LEED AP BD+ C</span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;color:#1F497D">SUSTAINABLE DESIGN COORDINATOR</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:red">HKS, INC.</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D">1919 McKINNEY AVENUE</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D">DALLAS, TX 75201</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D">214.969.5599 ext.3669</span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D"><a href="mailto:bwolfe@hksinc.com" target="_blank">bwolfe@hksinc.com</a></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;color:#1F497D"><a href="http://www.hksinc.com" target="_blank">www.hksinc.com</a></span></p>
<p class="MsoNormal"><span style="font-size:7.5pt;color:gray">If you are sending file(s) always use my </span><span style="font-size:10.0pt;color:gray"><a href="https://hks.thruinc.net/drop_box.asp?toemail=bwolfe@hksinc.com" target="_blank"><b><span style="color:#333333;text-decoration:none">Thru DROPBOX</span></b></a></span><span style="color:#1F497D"></span></p>
</div>
<p class="MsoNormal"><span style="color:#1F497D"> </span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt">From:</span></b><span style="font-size:10.0pt">
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a> [mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>]
<b>On Behalf Of </b>Brett M. West<br>
<b>Sent:</b> Monday, November 08, 2010 3:38 PM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Window Comparison</span></p>
</div>
</div><div><div></div><div class="h5">
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size:12.0pt">I am doing a model for a two
story office building with the windows making up approximately 30% of the
building’s exterior. My goal is to find what type of energy savings the
owner can expect by replacing all the existing single pane windows with double
pane, low e windows. When I change the window type to a double pane low-e
window I am seeing savings that are very small, around 3% of the total building
kWh.</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">For reference, the buildings
HVAC system consists of two air handlers (one per floor) ducted to a VAV system
with hot water reheat. </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Has anyone else tried to do
this type of comparison and if so what type of energy savings did you find? I
have attached my model pd2 and inp files for reference. Thanks in advance for
any information.</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Brett West</span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">RMF Engineering, Inc</span><b><span style="font-size:12.0pt;font-family:"Times New Roman","serif""></span></b></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif"">Ph:
843.971.9639</span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""><a href="mailto:bwest@rmf.com" target="_blank">bwest@rmf.com</a>
</span></p>
<p class="MsoNormal"> </p>
</div></div></div>
</div>
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