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<DIV><FONT color=#800000 size=2>One has to be careful about defining the shading
factor. The shaded portion of the window in PREBID is treated as the opaque part
of the window which may have a very different U-value than that of the
glass (glazing). The heat conducted across the window will be affected if a
glazing forms significantly large portion of the wall.</FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT color=#800000 size=2>Let me explain by the following example (a
single glazed window with wooden frame).</FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT color=#800000 size=2>If the shading coefficient is 0.5, beam and
diffuse radiation will pass through 50% of the area of the glass. The
remaining 50% of glass area would be treated as wood.</FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT color=#800000 size=2>In reality, heat conduction will take place
through the remaining 50% of the glass area (it should not be treated as
wood). (Imagine the difference when the c<FONT color=#800000
size=2>onductivity of glass = 2.88 kJ/m-K</FONT> and the c<FONT color=#800000
size=2>onductivity of wood = 0.54 kJ/m-K).</FONT></FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT color=#800000 size=2>A better method to model shading would be to
treat the beam and diffuse radiation with the shading coefficients in IISiBat
before it is given as input to Type 56.</FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT size=2><FONT color=#800000><FONT>Caution: The modified radiation to
be given separately for windows, it should not affect the radiation incident on
the walls. This would require creating a separate surface to contain the windows
only. Same c</FONT>aution is required also when Types 34 and 68 are used as
suggested by David.</FONT></FONT></DIV>
<DIV><FONT size=2><FONT color=#800000></FONT></FONT> </DIV>
<DIV><FONT size=2><FONT color=#800000>David: pl confirm the above
statement.</FONT></FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<DIV><FONT color=#800000 size=2>Anil Misra</FONT></DIV>
<DIV><FONT color=#800000 size=2></FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bradley@tess-inc.com href="mailto:bradley@tess-inc.com">David
Bradley</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=BLDG-SIM@gard.com
href="mailto:BLDG-SIM@gard.com">BLDG-SIM@gard.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, November 15, 2004 9:38
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [BLDG-SIM] Windows Shading
Coefficient</DIV>
<DIV><BR></DIV><FONT face=arial size=2>Dear </FONT>Maurizio,<BR><BR>
<BLOCKQUOTE class=cite cite="" type="cite"><FONT face=arial size=2>1) I'm
currently modelling in PREBID a residential building for which the montly
Shading Coefficients on the windows have been calculated with the software
ECOTECT. I insert the SC in the appropriate field ("external shading
coefficient") as an input and set the "view factor" to 0,5 (vertical
surfaces). It's the exact way? My doubt is that the solar incident radiation
is halved (view factor = 0,5) and then reduced of the
SC...</FONT></BLOCKQUOTE><BR>It is correct, provided that the shading
coefficient from Ecotect is the opaque fraction of the window (i.e. 1 =
completely shaded).<BR>The view factor to the sky (FSky) is only used for
longwave radiation so it will not interfere with shading.<BR><BR>The one thing
to bear in mind about PREBID's external and internal shading coefficient is
that the entered fraction effects both beam and diffuse radiation equally.
Thus if you enter a value of 0.5 for the external shading factor, half of the
incident diffuse radiation and half of the incident beam radiation will enter
the space. If you want to treat beam and diffuse radiation separately, you can
use one of the external shading models (Type34, or Type68).<BR><BR>
<BLOCKQUOTE class=cite cite="" type="cite"><FONT face=arial size=2>2) It's
possible to use old TESS libraries with TRNSYS 16 or are they already
comprised in the new version?</FONT></BLOCKQUOTE><BR>Because of the change in
coding standards for components between version 15 and 16, the TESS Libraries
<I>v. </I>1.x are not directly useable with TRNSYS <I>v</I> 16. We have,
however, expanded the libraries and released version 2.0, which are not only
compatible with TRNSYS 16 but are also backwards compatible with TRNSYS 15. If
you are interested in upgrading, you will be credited the full amount that you
paid for your version 1.x libraries toward the purchase of version 2.x
libraries. If you do not wish to upgrade then you can follow the steps laid
out in the TRNSYS 16 documentation that show you how to modify a TRNSYS 15
Type to make it accessible from TRNSYS 16. I will send along a second email
containing a document that lists the contents of the 12 version 2.0 libraries
as well as an order form that contains the pricing information. I would be
happy to answer any questions that you might have about them.<BR><BR>Kind
regards,<BR> David<BR><BR><BR><X-SIGSEP>
<P></X-SIGSEP><FONT
face="Courier New, Courier">****************************************************************************************<BR>Thermal
Energy System Specialists (TESS), LLC <BR>David
BRADLEY
2916 Marketplace Drive - Suite 104
<BR>Partner
Madison, WI 53719 <BR>Phone: (608) 274-2577 USA <BR>Fax: (608) 278-1475
<BR>E-mail: bradley@tess-inc.com <BR>Web Pages: <A
href="http://www.tess-inc.com/"
eudora="autourl">http://www.tess-inc.com</A>
and <A href="http://www.trnsys.com/"
eudora="autourl">http://www.trnsys.com<BR><BR></A>"Providing software
solutions for today's energy engineering projects"
<BR>****************************************************************************************<BR></FONT><PRE>
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