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<p class=MsoNormal><span style='color:#1F497D'>James,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>See ASHRAE 90.1 Figure 5-5, and
also definitions for unconditioned and semi-heated spaces in Section 3.2 (look
under Space). According to these definitions, naturally or mechanically
ventilated parking garages are not considered to be enclosed spaces, so the
wall between conditioned space and garage in your project should be treated as exterior
wall.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><span style='color:#1F497D'>Maria<o:p></o:p></span></p>
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<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b>On Behalf Of </b>James
Hansen<br>
<b>Sent:</b> Wednesday, April 22, 2009 2:48 PM<br>
<b>To:</b> BLDG-SIM@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] interior wall with window adjacent to unconditioned
area<o:p></o:p></span></p>
</div>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I have a general question about how to model and prove
compliance for a window in an interior wall that separates conditioned space
from unconditioned space.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>We have a project where there is a conditioned area in the
parking level with a full height storefront window system separating the room
from the unconditioned garage.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>As far as I know, this “wall” is actually an
interior wall per ASHRAE 90.1-2004. Or rather, it’s not defined as
an exterior wall (at least clearly enough). For certain modeling and
compliance programs, you can’t even assign a window to an interior
wall. To further complicate things, the entire wall is window, meaning
there is no actual cavity space for insulation (which proves difficult for
things like Comcheck compliance).<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Does anyone know how ASHRAE 90.1 views this
“wall”. Is it really an exterior walls? Are ALL walls
that separate conditioned from unconditioned space considered exterior
walls? If so, this is not properly defined in ASHRAE. And if not,
there doesn’t appear to be anywhere that governs U-values for windows in
INTERIOR walls that <u>separate conditioned from unconditioned area</u>.
In fact, from what I can tell, ASHRAE advises you to IGNORE windows in interior
walls. Which is all fine, unless your entire wall is window. But at
the same time, interior walls appear to require a maximum U-value of
0.120. For a window, this is nearly impossible.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Can anyone interpret 90.1 for me? Am I really allowed
to ignore windows in interior walls even if they separate conditioned space
from unconditioned space? <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks in advance!<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><b><span style='font-size:12.0pt;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='font-size:12.0pt;font-family:"Times New Roman","serif";color:black'>,
PE, LEED AP<o:p></o:p></span></b></p>
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