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<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>The overall window U-factor is usually not significantly higher
than center of glass (cog) one. It is only significantly higher if the
frame U-factor is significantly higher then cog U-factor and if spacer is highly
conductive. This is typically true for Aluminum framed windows and
Aluminum spacers. If you know frame U-factor and spacer material you can
simply calculate overall window U-factor by doing area weighting using the
following formula</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>U = (Af*Uf + Aeog*Ueog + Acog*Ucog)/A</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>where,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Af = total projected frame area</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Uf = frame U-factor</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Acog = Ag - (W-0.127)*(H-0.127)</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Wg = exposed glazing width</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Hg = exposed glazing height</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Ag = Area of exposed glazing</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Ag = W*H</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Aeog = Ag-Acog</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Ucog = center of glass U-factor</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Ueog = edge of glass U-factor</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>A = Total window area</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Uf and Ueog is usually determined using 2-D numerical
analysis. There are number of numerical tools for this but the best one
and easiest to use is THERM program (windows.lbl.gov). You will also
need WINDOW program (same web site) to prepare glazing system for THERM.
However, this is time-consuming process and it requires that you know all of the
details of glazing, spacer and frame. If you don't have those details and
you don't need absolute accuracy, easy way to get Ueog is to look in ASHRAE
Handbook of Fundamentals from one of prior years and to read Ueog from Figure
Ueog vs. Ucog (Figure 6 in 1989 Fundamentals). If you don't have access to
this book, let me know and I will send you scanned Figure.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Note: The above formula is a simplified version of the full window
U-factor calculation formula, and it assumes that all of the Uf and Ueog are the
same regardless of the position in a window (i.e., jambs, sill, head, mullion,
etc.). In your case, with not having all of the details, this formula is
appropriate. Otherwise, members in the above formula are under summation
signs, since each component of a window is accounted for
separately.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007><FONT face=Arial
color=#0000ff>Use of ISO 10077 standards is not appropriate here because we use
different boundary conditions, so unless this is for some calculations in Europe
I would strongly advise not to use these standards.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921082714-18042007></SPAN><FONT
face=Arial><FONT color=#0000ff></FONT></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT color=#0000ff>R<SPAN
class=921082714-18042007>egards,</SPAN></FONT></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial><FONT color=#0000ff><SPAN
class=921082714-18042007>Charlie Curcija</SPAN></FONT></FONT></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> BLDG-SIM@gard.com
[mailto:BLDG-SIM@gard.com] <B>On Behalf Of </B>Annalisa
Simonella<BR><B>Sent:</B> Wednesday, April 18, 2007 4:37 AM<BR><B>To:</B>
BLDG-SIM@gard.com<BR><B>Subject:</B> [BLDG-SIM] glass
u-vals<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi
Aaron,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">The overall U-value is
usually significantly higher than the centre-pane U-value. In order to estimate
the overall U-value of curtain walls or windows you need to include the frames
U-values and the edge effects and the additional effect of point thermal bridges
if present (structural connections through the facade or
window).<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">You may find some
guidance in the NFRC standards <A
href="http://www.nfrc.org/technicaldocs.aspx">http://www.nfrc.org/technicaldocs.aspx</A>
and you may use the software THERM (downloadable from the LBNL website <A
href="http://windows.lbl.gov/software/">http://windows.lbl.gov/software/</A> )
to calculate the U-value + edge effects of frames. <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">You may also find some
guidance in the EN ISO 10077-1 and EN ISO 10077-2 which define a different
method from the NFRC one, also the first one gives simplified method and
includes a table with pre-calculated linear thermal transmittances (edge
effect).<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I hope it
helps.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Best
regards,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Annalisa.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<P><FONT face=Arial color=navy size=1><SPAN lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">Annalisa
Simonella</SPAN></FONT><FONT color=navy><SPAN lang=EN-US style="COLOR: navy">
</SPAN><o:p></o:p></FONT></P>
<P><FONT face=Arial color=navy size=1><SPAN lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">Arup<B><SPAN
style="FONT-WEIGHT: bold">FacadeEngineering</SPAN></B></SPAN></FONT><FONT
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lang=EN-US style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">13 Fitzroy
Street</SPAN></FONT></st1:Street><FONT color=navy><SPAN style="COLOR: navy">
<BR></SPAN></FONT><st1:City w:st="on"><FONT face=Arial color=navy size=1><SPAN
lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">London</SPAN></FONT></st1:City><FONT
face=Arial color=navy size=1><SPAN lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial"> <st1:PostalCode
w:st="on">W1T 4BQ</st1:PostalCode></SPAN></FONT></st1:address><FONT
color=navy><SPAN lang=EN-US style="COLOR: navy"> </SPAN><o:p></o:p></FONT></P>
<P><FONT face=Arial color=navy size=1><SPAN lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">T +44 (0)207 75
54593</SPAN></FONT><FONT color=navy><SPAN style="COLOR: navy">
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style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">F +44 (0)207 75
53626</SPAN></FONT><FONT color=navy><SPAN style="COLOR: navy">
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style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial">M +44 (0)77 1781
4793</SPAN></FONT><FONT color=navy><SPAN lang=EN-US style="COLOR: navy">
</SPAN><o:p></o:p></FONT></P>
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style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial"><A
href="mailto:annalisa.simonella@arup.com">mailto:annalisa.simonella@arup.com</A></SPAN></FONT><FONT
color=navy><SPAN style="COLOR: navy"> <BR></SPAN></FONT><FONT face=Arial
color=navy size=1><SPAN lang=EN-US
style="FONT-SIZE: 7.5pt; COLOR: navy; FONT-FAMILY: Arial"><A
href="http://www.arup.com/facadeengineering/">http://www.arup.com/facadeengineering/</A></SPAN></FONT><FONT
color=navy><SPAN lang=EN-US style="COLOR: navy">
</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face="Times New Roman" size=3><SPAN lang=EN-US style="FONT-SIZE: 12pt">
<HR tabIndex=-1 align=center width="100%" SIZE=2>
</SPAN></FONT></DIV>
<P class=MsoNormal><B><FONT face=Tahoma size=2><SPAN lang=EN-US
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN lang=EN-US
style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> BLDG-SIM@gard.com
[mailto:BLDG-SIM@gard.com] <B><SPAN style="FONT-WEIGHT: bold">On Behalf Of
</SPAN></B>Dahlstrom, Aaron<BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> 18 April 2007 04:24<BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> BLDG-SIM@gard.com<BR><B><SPAN
style="FONT-WEIGHT: bold">Subject:</SPAN></B> [BLDG-SIM] glass
u-vals</SPAN></FONT><SPAN lang=EN-US><o:p></o:p></SPAN></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">ASHRAE 90.1 window U-vals are for
the "assembly."</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Manufacturer's data for my project
is for "center of glass."</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Is anyone familiar with a way to get
from one to the other?</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I have a frame type and u-value;
however, Fund. Chap 31 seems to caution against doing hand calcs due to
edge-of-glass effects.</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thanks,</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<P class=MsoNormal><EM><I><FONT face="Bookman Old Style" size=3><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 'Bookman Old Style'">Aaron
Dahlstrom</SPAN></FONT></I></EM><o:p></o:p></P>
<P class=MsoNormal><FONT face="Century Gothic" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Century Gothic'">AKF Engineers,
LLP<BR></SPAN></FONT><st1:Street w:st="on"><st1:address w:st="on"><FONT
face="Century Gothic" size=1><U1:STREET u2:st="on"><U1:ADDRESS u2:st="on"><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: 'Century Gothic'">1500 Walnut Street, Suite
1400</SPAN></FONT></st1:address></st1:Street><FONT face="Century Gothic"
size=1><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: 'Century Gothic'"><BR><st1:place
w:st="on"><st1:City w:st="on"></U1:ADDRESS></U1:STREET><U1:PLACE
u2:st="on"><U1:CITY u2:st="on">Philadelphia</st1:City></U1:CITY>, <U1:STATE
u2:st="on"><st1:State w:st="on">PA</U1:STATE></st1:State> <U1:POSTALCODE
u2:st="on"><st1:PostalCode
w:st="on">19102</U1:POSTALCODE></st1:PostalCode></st1:place></U1:PLACE>
<BR>Phone: (215)
282-2169<BR>Fax: (215)
735-6706<BR></SPAN></FONT><FONT face="Century Gothic" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Century Gothic'"><A
href="http://www.akf-engineers.com/"><FONT color=black><SPAN
style="COLOR: black">www.akf-engineers.com</SPAN></FONT></A></SPAN></FONT><o:p></o:p></P>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt"><o:p> </o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt"><o:p> </o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">==================<o:p></o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">You received this e-mail because you are subscribed <o:p></o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">to the BLDG-SIM@GARD.COM mailing list. To unsubscribe <o:p></o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">from this mailing list send a blank message to <o:p></o:p></SPAN></FONT></PRE><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">BLDG-SIM-UNSUBSCRIBE@GARD.COM<o:p></o:p></SPAN></FONT></PRE></DIV><PRE>____________________________________________________________
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