[Radiance-general] Re: Fritted Glass

[Peter Apian-Bennewitz]

John de Valpine wrote:

> Based on the data that I have seen available from
> manufacturers of glazing sytems, the measured
> performance data are for the composite glazing system
> (with the frit applied). What are your assumptions
> about the fritting material itself? How do you go
> about determining the frit definition as a trans? Can
> you walk through your process in greater detail for
> the trans material?
...
> > 2)....Definition of Frit material;
> >
> > void trans blackfrit
> > 0
> > 0
> > 7 0.091 0.091 0.091 0.010 0.150 0.556 0.000
...

The trans model can be fitted to BRTF data of the material (rarely
available from manufacturers, but quite easily measured:
http://www.ise.fhg.de/radiance/gonio-photometer), resulting in a
validated trans model with known error bounds. If trans is not a
suitable fit, use BRTDfunc with you own model: Functions which
empirically model the underlying physics of the material (e.g. extruded)
and steered with few variables (2-6 approx.) fit best (german
description found at http://www.pab-opto.de/apian/phd/phd.html).

-Peter

-- 
 pab-opto, Freiburg, Germany, www.pab-opto.de