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<div>This is an interesting one. I gave it some thought a few years back when I came across precast concrete blades projecting outside (shades), but directly exposed to the outside. I thought of using Therm to estimate the effective U-Value of the wall for winter heat loss purposes but didn't take it any further at the time.</div><div> </div>The air gap between the corrugated metal and concrete provides a relatively significant level of insulation. If your effective exterior surface area is say 1.3 of your projected surface area what you would ideally be able to do is raise your external heat transfer coefficient by the same or similar factor. I don't know of a way to do this in DOE-2.2 other than modify surface roughness, but you could play with the cavity air-gap insulation value to derate the assembly but then this value does not vary with wind speed ... . This would approximate only the modified convection effects.<div><br class="webkit-block-placeholder"></div><div>As for solar radiation it should be similar as the corrugation would self shade and thus the wall always sees the projected area normal to the sun ... . As for long wave radiative heat transfer you could max out the emissivity but this only gives you a 10-15% max increase given what the unmodified emissivity likely is. Could you play with sky-view factors (I think you can vary them in 2.2) to increase the amount of sky a surface sees to account for the extended surface area .... ?</div><div><br class="webkit-block-placeholder"></div><div>Good luck I would be interested if any of the forum participants have come across refereed papers in this area. In parts of Australia the cold bridging created by a concrete blade or an aluminium curtainwall fin can be significant. The latter is disturbingly common on non-thermally broken curtainwall suites. I reckon the benefits of the shading could be outweighed by the unaccounted penalties ...</div><div><br><div>Regards,</div><div>Graham <br><div><div>On 29/01/2008, at 4:42 AM, Steven Savich wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="PostalCode"> <o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="Street"> <o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="address"> <o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> <o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"> <o:smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="State"> <!--[if !mso]> <style> st1\:*{behavior:url(#default#ieooui) } </style> <![endif]--> <!--[if gte mso 9]><xml> <o:shapedefaults v:ext="edit" spidmax="1026" /> </xml><![endif]--><!--[if gte mso 9]><xml> <o:shapelayout v:ext="edit"> <o:idmap v:ext="edit" data="1" /> </o:shapelayout></xml><![endif]--> <div class="Section1"><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial">Hello all,<o:p></o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial"><o:p> </o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial">I’m about to start working on a model for an existing classroom building. The exterior walls are uninsulated concrete with a “corrugated” exterior surface that would appear to me to greatly increase the effective surface area for winter heat loss/summer heat gain. Any thoughts about how to approach modeling with this in eQuest?<o:p></o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial"><o:p> </o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial">Thanks,<o:p></o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial"><o:p> </o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial">Steven<o:p></o:p></span></font></p><p class="MsoNormal"><font size="2" face="Arial"><span style="font-size:10.0pt; font-family:Arial"><o:p> </o:p></span></font></p><p class="MsoNormal"><font size="3" face="Bookman Old Style"><span style="font-size:12.0pt;font-family:"Bookman Old Style"">Steven Savich</span></font><o:p></o:p></p><p class="MsoNormal"><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family:"Bookman Old Style"">Systems West Engineers</span></font><o:p></o:p></p><p class="MsoNormal"><st1:street w:st="on"><st1:address w:st="on"><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family:"Bookman Old Style"">411 High Street</span></font></st1:address></st1:street><o:p></o:p></p><p class="MsoNormal"><st1:place w:st="on"><st1:city w:st="on"><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family:"Bookman Old Style"">Eugene</span></font></st1:city><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family: "Bookman Old Style"">, <st1:state w:st="on">OR</st1:state> <st1:postalcode w:st="on">97401-2427</st1:postalcode></span></font></st1:place><o:p></o:p></p><p class="MsoNormal"><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family:"Bookman Old Style"">(541) 342-7210</span></font><o:p></o:p></p><p class="MsoNormal"><font size="2" face="Bookman Old Style"><span style="font-size:10.0pt;font-family:"Bookman Old Style"">(541) 342-7220 (fax)</span></font><o:p></o:p></p><p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size: 12.0pt"><o:p> </o:p></span></font></p> </div> </o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype></o:smarttagtype><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Bldg-sim mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Bldg-sim@lists.onebuilding.org">Bldg-sim@lists.onebuilding.org</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a></div> </blockquote></div><br></div></div></body></html>