[Radiance-general] Re: Glazing transparency/reflectivity study

[Jack de Valpine]

Hi Galen,

It has been a while, but I think that the color/tint comes from the rgb 
values for the coated glass. So the color would be conveyed by "VE2-2M 
on Evergreen" monolithic export from Optics 5. So this should account 
for the color of the coated glass. However, I think that I have to defer 
to Greg on this for confirmation.

Note for Viracon:

    <type><color>-<transmittance>

    so
    type = VE = Low-E
    color = 2 = Green
    transmittance = 2M = ~70%

    if you want "Evergreen" you need to look at color 8.... so VE8-2M


One way to sanity check is to run a single layer output from glaze and 
specify s1 as clear and s2 as VE2-2M on evergreen. The last three lines 
of the material description should give you:

    Rext_r Rext_g Rext_b
    Rint_r Rint_g Rint_b
    Tr Tg Tb

The rgb components should be the same as those exported from Optics5 
(even though you are specifying "clear" for one layer).

Hope this helps.

-Jack



Galen Burrell wrote:
> Thanks Jack.
>
> All seems clear and I've got some results that I'm pretty happy with.  One thing I'm still a little unclear about is how you would apply a low-e film to a non-clear glass (i.e. tinted green, blue, etc) if the script requires one surface to be "clear" for each pane.
>
> For example:
> VE2-2M (http://www.viracon.com/makeupsheet.php?id=3840) has the VE-2M coating applied to Evergreen glass on the #2 surface.  As it is now, I would input:
> Surface 1 - Clear
> Surface 2 - VE2-2M on evergreen (from optics 5 data)
> Surface 3 - Clear
> Surface 4 - Clear
>
> Is there an easy hack to make Surface 1 evergreen instead of clear?
>
> Thanks,
> Galen
>
>
> -----Original Message-----
> Date: Thu, 15 Jan 2009 21:07:06 -0500
> From: Jack de Valpine <jedev at visarc.com>
> Subject: [Radiance-general] Re: Radiance-general Digest, Vol 59, Issue
>         8
> To: Galen Burrell <Galen.Burrell at arup.com.au>
> Cc: Radiance general discussion <radiance-general at radiance-online.org>
> Message-ID: <496FEBCA.70906 at visarc.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi Galen,
>
> No problem.
>
> Regarding the header
>
>     * Rc<r,g,b> - these are the rgb components for the reflectance on
>       the "coated" side of the monolithic glass
>     * Rg<r,g,b> - these are the rgb components for the reflectance on
>       the non-coated side of the monolithic glass
>     * T<r,g,b> - these are the rgb components for the transmittance for
>       the monolithic glass
>     * Part - this is a boolean value
>           o 0 means this is a regular glass
>           o 1 means this is a frit - if this is the case the "coated"
>             side reflectance needs to represent the reflectance of the
>             frit at 100% coverage which should be possible to extract
>             from the glazing manufacturer
>
> The RGB values are extracted from the file generated for a "radiance"
> export from Optics. This should be for a single pane monolithic glass
> description (not a multi-layer make-up). The file will have three
> Radiance material definitions, the two BRDTfunc definitions are the ones
> to pay attention to. The makeup is something like the following:
>
>     void BRTDfunc some.glass.front
>     10
>
>         Rfr Rfg Rfb
>         Tr Tg Tb
>         0   0   0
>         .
>
>     9 0 0 0 0 0 0 0 0 0
>
>     void BRTDfunc some.glass.back
>     10
>
>         Rbr Rbg Rbb
>         Tr Tg Tb
>         0   0   0
>         .
>
>     9 0 0 0 0 0 0 0 0 0
>
> So you need to take the two rgb triples for reflectance and one for
> transmittance. So an entry in the data file could look like this (you
> will need to figure which represents the coated side if needed):
>
>     Surface Tr      Tg      Tb      Rcr     Rcg     Rcb     Rgr     Rgg     Rgb     Part
>     <name>  Tr  Tg      Tb      Rfr     Rfg     Rfb     Rbr     Rbg     Rbb     0
>
>
>
> A file for a double pane insulating unit might look like the following:
>
>     Surface Tr      Tg      Tb      Rcr     Rcg     Rcb     Rgr     Rgg     Rgb     Part
>     green-lowe  Tr      Tg      Tb      Rfr     Rfg     Rfb     Rbr     Rbg     Rbb     0
>
>
> The glaze script contains a default "clear" glass. I seem to recall that
> this is required for the script to output a material description (eg it
> must have a "clear" glass description"). If this is not suitable the
> script requires some modification, which I think I can offer some
> guidance on so that you can include your own "clear" glass description.
>
> I would suggest before you do anything else you should test out the
> script as is with the built in values. This will let you see how it
> works. You will assign different materials to different layers to build
> up the composite unit.
>
> Try it out and let me know if you have more questions.
>
> -Jack
>
>
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>   

-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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