[BLDG-SIM] ASHRAE 90.1 - window SHGC

[D. Charlie Curcija]

International Glazing Database (IGDB), which is part of WINDOW 5.2 program
(windows.lbl.gov) contains several hundred individual glass layers whose
solar transmittance is at or below 0.3, which, as a part of glazing system
and whole fenestration product, would produce SHGC of 0.25 or lower, which
meets ASHRAE 90.1 for all climate zones.  The best choice for low SHGC
windows is so called spectrally selective low-e, and there are at least 100
glass products with this type of low-e coating.  The cost of these products
is only marginally higher than the cost of clear glass.
 
I think that you are definitely overlooking something.
 
Having said that, I do want to state that the use of low SHGC products in
heating dominated climates (anything at or above climate zone 5) is wrong
and is the major flaw of both ASHRAE 90.1 and IECC 2006, particularly for
orientations with potentially high solar gain in the winter, such as South
orientation.
 
D. Charlie Curcija
Carli, Inc.
18 Tanglewood Rd.
Amherst, MA 01002
 
Tel: (413) 256-4647
Fax: (413) 256-4823
cell: (413) 575-3487
email:  <blocked::mailto:curcija at fenestration.com> curcija at fenestration.com
web:  <http://www.fenestration.com/> http://www.fenestration.com
 
Support open document format as the best way to assure full compatibility
and interoperability! 
 
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From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Scott Runyon
Sent: Monday, April 09, 2007 7:52 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] ASHRAE 90.1 - window SHGC



When modeling my design case, I find that most windows cannot achieve the
minimum SHGC suggested in ASHRAE 90.1.

 

Why would ASHRAE set unattainable minimum values?      

 

Am I overlooking something in ASHRAE 90.1???

 

Any help would be appreciated.

Thanks,

Scott

 



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