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<p class=MsoNormal>I wanted to run something by everyone to see if this is how
most people model underground walls: <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>For my climate zone (4A), the required C-factor for
Underground Wall is 1.140 (no U-value listed).<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>If you go to Appendix A of 90.1-2004, specifically sections
A4.1 and Table A4.2, I *<b>think</b>* that you come to the conclusion that the
baseline underground walls should be modeled as 8 inch medium weight concrete
block with a density of 115 lb/ft3, solid grouted cores, and NO
INSULATION. This is what A4.1 says, and the published C-factors in Table
A4.2 indicate that a C-factor of 1.140 is obtained using this wall and no
framing / no insulation.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>If you then refer to Table A3.1C, for that wall type, sure
enough a C-factor of 1.140 is listed with a corresponding U-value of 0.58.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>When I run my baseline model with an underground wall
construction having a U-value of 0.58, I end up with way more cooling hours and
energy that my proposed model, which has R-13 insulation. This is
presumably because those underground spaces are constantly losing heat thru the
poor wall construction to the 55 degree earth heat sink (or whatever eQuest
calculates it as).<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’m not complaining, as it makes the proposed system
look that much more efficient, but I just wanted to double check that I’m
doing this right.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>On a side note, I’m having a tough time reducing my
unmet load hours for the underground VAV system, but that’s besides the
point…<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks!<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-family:"Arial","sans-serif";color:teal'>GHT
Limited<br>
</span></b><b><span style='font-family:"Arial","sans-serif"'><ns0:PersonName><span
style='color:black'>James Hansen</span></ns0:PersonName></span></b><b><span
style='color:black'>, PE, LEED AP<o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Senior Associate</span></b><b><span style='color:black'><o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'><ns0:Street><ns0:address><span
style='color:black'>1010 N. Glebe Rd, Suite 200</span></ns0:address></ns0:Street></span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'><ns0:place><ns0:City><span
style='color:black'>Arlington</span></ns0:City><span style='color:black'>, </span><ns0:State><span
style='color:black'>VA</span></ns0:State><span style='color:black'> </span><ns0:PostalCode><span
style='color:black'>22201-4749</span></ns0:PostalCode></ns0:place></span><span
style='color:black'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif";
color:black'>703-338-5754 (Cell)</span><span style='color:black'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif";
color:black'>703-243-1200 (Office)</span><span style='color:black'><o:p></o:p></span></p>
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color:black'>703-276-1376 (Fax)</span><span style='color:black'><o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:teal'><a
href="http://www.ghtltd.com/"><span style='font-size:10.0pt;color:blue'>www.ghtltd.com</span></a><o:p></o:p></span></p>
<p class=MsoNormal><b><span style='color:#31849B'><o:p> </o:p></span></b></p>
<p class=MsoNormal><o:p> </o:p></p>
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