[BLDG-SIM] Window Thermal Performance and DOE2.2

[Sean Henry]

Dear BLDG-SIM Users:
As many of you are aware, glazing manufacturer's performance data from a
variety of commercial glass manufacturers recently has been made
available when specifying from the Glass Library for DOE2.2/eQuest. As I
understand it, these values are based on LBNL's WINDOW 5 glazing
analysis program. The main advantage of specifying this way is that this
method more accurately includes solar incident angle affects on the
percentage of direct transmission of solar gains through the
fenestration. This method is in lieu of using the Simplified
Specification method where the user directly inputs an overall
conductance, shade coefficient, VLT and outside emissivity. 
 
My question is this: When using the Glass Library specification method,
how are users out there accounting for the frame affect to the windows
being modeled when in Detailed Edit Mode? There isn't an input available
to specify the window frame being used.
 
The eQuest Wizard allows the user to assign frames to specific glazing
type (including the Library values mentioned above). Ostensibly the
Wizard is de-rating the center of glass U factors obtained from the
glass library data to account for frame affects and thus providing an
overall U value for the simulation. However recent discussion at the May
BSUG meeting leads one to question if this assumption is valid. Maybe
Scott Criswell or Kevin Madison can shed some light on this?
 
Best Regards,
Sean Henry
Interface Engineering
Portland, OR
 
 
 
 
 
 
 
 
 
 


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