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<p class="MsoNormal">In the past I’ve done a conversion of F-factor (perimeter based) slab-on-grade heat loss to U-factor (area) and input that in on a zone-by-zone basis if I really wanted to nail down SOG heat loss.
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<p class="MsoNormal">Example- Space is 20’ x 30’, but the exposed perimeter is only two of the faces (20’ + 30’). Lets say it is uninsulated SOG.
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<p class="MsoNormal">F-factor from 90.1: F = 0.73 Btu/(hr*ft*F)<br>
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Perimeter based heat loss: 0.73 Btu/(hr*ft*F) * 5 ft’ = 36.5 BTU/(hr *F)<o:p></o:p></p>
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<p class="MsoNormal">Then we can back-calculate the U-factor to assume for the whole floor to equate to that heat loss: 36.5 BTU/(hr *F) = 600 SF * X BTU/(hr*SF*F) -> U = 0.0608 BTU/(hr*SF*F)<o:p></o:p></p>
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<p class="MsoNormal">You can create a custom floor construction for each space to provide the U-factor to produce equivalent heat loss that the F-factor calcs are telling you lose. For purely core zones (no exposed perimeter), I guess the F-factor calcs are
telling us were not really losing heat through that slab (doesn’t’ seem right, but it probably is relatively small)
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<b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#6F1200">Nathan Miller, PE, LEED AP BD+C</span></b><b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#632423"> –
</span></b><i><span style="font-size:8.0pt;font-family:"Verdana",sans-serif;color:black">Mechanical Engineer/Senior Energy Analyst</span></i><b><span style="font-size:9.0pt;font-family:"Verdana",sans-serif;color:#632423"><o:p></o:p></span></b></p>
<p class="MsoNormal" style="margin-top:3.0pt;line-height:115%"><b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#6F1200">RUSHING</span></b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#BFAB7F">
</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:black">|</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#BFAB7F">
</span><b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#6F1200">O</span></b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#A50021">
</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:black">206-285-7100 |</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#BFAB7F">
</span><b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#6F1200">C</span></b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#A50021">
</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:black">207-650-3942</span><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#BFAB7F"><o:p></o:p></span></p>
<p class="MsoNormal" style="line-height:115%"><b><span style="font-size:8.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#6F1200"><a href="http://www.rushingco.com/"><span style="color:#6F1200">www.rushingco.com</span></a></span></b><b><span style="font-size:9.0pt;line-height:115%;font-family:"Verdana",sans-serif;color:#6F1200"><o:p></o:p></span></b></p>
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<p class="MsoNormal"><b>From:</b> Equest-users [mailto:equest-users-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Paul Diglio via Equest-users<br>
<b>Sent:</b> Friday, February 2, 2018 2:19 PM<br>
<b>To:</b> equest-users@onebuilding.org<br>
<b>Subject:</b> [Equest-users] Slab on Grade Floor Heat Loss<o:p></o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">I recently submitted a model to the local utility company for an incentive. Part of the buildings' first floor is slab on grade.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">One of the comments I received back is that this erroneously shows up as an exterior surface and I should delete all the slab on grade floors
in the component tree. Doesn't seem right to me.<br>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">I did a few and it does reduce the overall energy consumption. In the 3D model, no floors show, just open to the interior of the zone.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">So is eQuest assuming that without this floor, there is no heat loss out the bottom of the zone? Is this reasonable?<br>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">Thank you,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:12.0pt;font-family:"Helvetica Neue";color:black">Paul Diglio<o:p></o:p></span></p>
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