[Equest-users] Integrated Window Blinds in Dual Pane Windows

Joe Huang yjhuang at whiteboxtechnologies.com
Sun Dec 23 00:45:42 PST 2012


I think this is a very unwise way to model complex fenestration, because you'll be using 
the Simple Window Model in DOE-2, which assumes that the angular
variation of SHGC and temperature variation of U-factor are the same as for single-pane 
clear glass.  I haven't followed the development of LBNL's Window (not Windows :-)) 
program for the past five years, but the program used to produce a text "WINDOW 4" file 
that can be read into DOE-2 or eQUEST.    If this is still possible, I would recommend 
using that method.  There are still the questions of venetian blind shading that is not 
dependent only on the angle of incidence, but also the azimuth relative to the blinds 
(there must be a technical term for this, but I don't know that off the cuff), and if you 
want to change the angle of the venetian blinds depending on season.  I can think of ways 
of dealing with these issues, but it would require writing a USER FUNCTION, which I don't 
think has been implemented in DOE-2.2.


Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 12/22/2012 5:51 PM, Peter Baumstark wrote:
> Ok. . .  I have a situation where I'm modeling a facility relative to ASHRAE 90.1 
> baseline.  The customer is using dual pane, low-e windows, with integrated venetian 
> blinds between the two panes of glass.  One pane is low-e and the other is clear.  Air 
> gap between the two (not Argon or anything like that).
> I use the LBNL Windows tool, with blinds set at 45 deg, and the blinds increase the 
> window assembly U value and SHGC significantly.
> So for performance relative to 90.1, would it be acceptable to simply utilize the U & 
> SHGC from with Windows tool?  Are there any restrictions on the angle of the blinds, or 
> whether the angle should be different for winter vs summer?
> I'd appreciate any guidance on how to best model this scenario.
> Thank you,
> Pete Baumstark
> San Jose, CA
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