[Radiance-general] Modeling reflective glazing and glazing with ceramic frit

[Gregory J. Ward]

Hi Marija,

> I've just tried this new script and if I understood it well, it  
> determines whether output material should be glass or BRTDfunc  
> using next conditions:
> abs(back_reflectance - front_reflectance)<0.05 -> glass material
> transmittance>0.645 and abs(back_reflectance - front_reflectance) 
> >0.05 -> BRTFfunc with '*clear' functions
> transmittance<0.645 and abs(back_reflectance - front_reflectance) 
> >0.05 -> BRTFfunc with '*bronze' functions
> Right?

Yes, that looks about right, except that the threshold between front  
and back reflectance is 0.005 (0.5%), rather than 0.05.

> Few questions:
> - For Plexiglas® MC (NFRC ID= 2604), glass material parameters are  
> >1 ( 1.002 1.004 1.001). I think glass transmissivity should be <=1 ?!

Does sound strange.  You wouldn't happen to have the Optics5 output  
on hand you could send me?

> - For materials that are exported from OPTICS5 and have name like  
> "abc_def" (with "_"), optics2rad doesn't define output radiance  
> materials, because it doesn't recognize the format.

Hmmm.  I see the problem, but there's not much I can do to fix it,  
because rcalc uses the underscore character to find the end of the  
name.  I guess you just have to manually edit the Optics5 output to  
eliminate the underscores in the middle of names.  I could probably  
come up with a sed script to do it if it's really a problem.

> -Is window.cal relevant only for one-layer glazings? I suppose for  
> double layer we should use glaze.csh script as before.

Yes, the basic model is only really valid for single-layer glazings.   
The glaze.csh script sponsored by Visarc is more flexible (and  
accurate).

-Greg