[Radiance-general] Description of complex glass systems (geometry+
material)
marina aviles olmos
marina.aviles at gmail.com
Tue May 5 08:05:45 PDT 2009
Hi Robin, hi All
yes I want to simulate a laminated glass in a double glass system. This
laminated glass is a prototyp of a glazing system and there is no
information about it anywhere. It is also a quite complicated system
with embeded coating and interlayer and I can get its description from
Optics5. That's why I think the way to describe this glasses are with
the spectrometer measurements.
I am still not sure anyway if I describe the glasses propertly.
Does anybody knows if this is right like this:
#window geometry:
double_glazing_a polygon window
0
0
12 0 -0.18 0
0 -0.18 3.34
4.13 -0.18 3.34
4.13 -0.18 0
#window material:
void BRTDfunc double_glazing_a
10
if(Rdot,cr(fr(rf1_r),ft(t1_r),fr(rf2_r)),cr(fr(rb2_r),ft(t2_r),fr(rb1_r)))
if(Rdot,cr(fr(rf1_g),ft(t1_g),fr(rf2_g)),cr(fr(rb2_g),ft(t2_g),fr(rb1_g)))
if(Rdot,cr(fr(rf1_b),ft(t1_b),fr(rf2_b)),cr(fr(rb2_b),ft(t2_b),fr(rb1_b)))
ft(t1_r)*ft(t2_r)
ft(t1_g)*ft(t2_g)
ft(t1_b)*ft(t2_b)
0 0 0
glaze2.cal
0
9
0 0 0
0 0 0
0 0 0
where I just have to substitute the next measured data:
Red: 700nm -- rf1_r rb1_r rf2_r rb2_r t1_r t2_r
Green: 546nm -- rf1_g rb1_g rf2_g rb2_g t1_g t2_g
Blue: 436 -- rf1_b rb1_b rf2_b rb2_b t1_b t2_b
Thanks again,
Marina
Robin Mitchell wrote:
> Marina -
>
> I have not followed this thread very closely, so I don't know exactly what
> you are trying to model in Radiance, but thought I would make one comment,
> which may or may not be useful.
>
> You say that the constructions you are trying to model are not in the IGDB,
> and then you say that you want to model a laminate.
>
> I just want to make sure that you know you can make a laminate in Optics,
> depending on what you are using for the glass and interlayer values.
>
> There is a detailed write-up of how to make laminates in Optics on our
> Optics Knowledge Base website:
>
> http://windows.lbl.gov/materials/optics5/CurrentVersion/Optics_Knowledge_Bas
> e.htm
>
> Click on the link for "NFRC Procedure for Creating Laminates" and you will
> get to another page, and there you can click on "Laminate Procedures" for
> the detailed description of the process. Here is a direct link to that PDF:
> http://windows.lbl.gov/software/NFRC/Training/LaminateProcedure-Final.pdf
>
>
> Robin Mitchell
> Windows & Daylighting Group
> Lawrence Berkeley National Laboratory
>
> -----Original Message-----
> From: radiance-general-bounces at radiance-online.org
> [mailto:radiance-general-bounces at radiance-online.org] On Behalf Of marina
> aviles olmos
> Sent: Monday, May 04, 2009 8:24 AM
> To: Radiance general discussion
> Subject: Re: [Radiance-general] Description of complex glass systems
> (geometry+ material)
>
> Hi Marija, hi Jack
>
> Thanks for your mails.
> Some glass types I want to simulate are not in the IGDB, so I will
> describe the glasses with the measurements-method,
> but I am not really sure I have understood this method properly. There
> are those precisions that make radiance so great, but sometimes also
> difficult to learn. Could you tell me if this would be then right as
> follows?
>
> This is the hole double glazing geometry description:
>
> #window geometry:
>
> double_glazing_a polygon window
> 0
> 0
> 12 0 -0.18 0
> 0 -0.18 3.34
> 4.13 -0.18 3.34
> 4.13 -0.18 0
>
> Then I should measure the interior pane (a laminated float glass with an
> interlayer) and separately the exterior pane (a 4 mm float glass). The
> hole input data are then:
>
> Red: 700nm -- rf1_r rb1_r rf2_r rb2_r t1_r t2_r
> Green: 546nm -- rf1_g rb1_g rf2_g rb2_g t1_g t2_g
> Blue: 436 -- rf1_b rb1_b rf2_b rb2_b t1_b t2_b
>
> Then substitute these in the formel you said and this would be the
> complete description of the double glazing material:
>
> #window material:
>
> void BRTDfunc double_glazing_a
> 10
> if(Rdot,cr(fr(rf1_r),ft(t1_r),fr(rf2_r)),cr(fr(rb2_r),ft(t2_r),fr(rb1_r)))
> if(Rdot,cr(fr(rf1_g),ft(t1_g),fr(rf2_g)),cr(fr(rb2_g),ft(t2_g),fr(rb1_g)))
> if(Rdot,cr(fr(rf1_b),ft(t1_b),fr(rf2_b)),cr(fr(rb2_b),ft(t2_b),fr(rb1_b)))
> ft(t1_r)*ft(t2_r)
> ft(t1_g)*ft(t2_g)
> ft(t1_b)*ft(t2_b)
> 0 0 0
> glaze2.cal
>
> 0
> 9
> 0 0 0
> 0 0 0
> 0 0 0
>
>
>
> I also try to understand how this calculation system is related to the
> physical process. So I have another question.
> If I measure with a spectrometer the complete normal reflectance and
> transmittance of a double glazing, the interior reflectances are already
> in the total measurement. So I understand that, also when in the
> physical reality the total reflectance of a double glazing could be the
> input data for the simulation, the calculation system of radiance
> calculates only right if you specify the interior reflectances and the
> calculation take place within the BRTD function. Am I right on that?
>
> Thanks again,
>
> Marina
>
>
>
>
>
>
> Hi Marina,
>
> Yes you want to describe the glass geometry, that is one polygon
> representing the multiple layers of the physical makeup. The material is
> what should represent the behavior. If you take the output from Optics
> and run it through optics2rad you will get a single BRTDfunc material
> description. One thing to be careful of is that this is dependent on the
> correct orientation (normal) of the glass geometry. I believe that the
> normal is supposed to be pointing "into" the interior of the building.
> One way to check normal orientation in radiance is to assign
> (temporaryily) a "glow" material to the glass geometry and view it. The
> sides that are "black" are the back sides of the geometry, the sides
> that are not black are the positive normal side.
>
> Regards,
>
> -Jack de Valpine
>
>
>
>
> Marija Velickovic wrote:
>
>> Hi Marina,
>>
>> 1.glazing geometry
>>
>> Always define glazing object as a polygon, no matter how many layers
>> of glass it contains in real world.
>> Double clear, laminated and other glazings differ only in BRTDfunc
>> (light transmittance and reflectance distribution function), while
>> real glazing width is not important here.
>>
>> Note that polygon face should be oriented towards building interior.
>>
>> ##########
>> 2.glazing material
>> Since BRTD function for double glazing is different then for single
>> glazing, I don't suggest using of simple glass material.
>> Procedure we use is next:
>> *Measure each glass layer transmittance and reflectance data. If you
>> can measure their r,g,b components it is good, if not use the same
>> value for all 3 components.
>> or
>> *Export from IGDB (using Optics5 I suppose), each layer separately.
>> And write down transmittances/reflectances you have in BRTD functions.
>> Note that in Optics5 front side of the glazing is towards outside, so
>> their front and Radiance "front" are different.
>>
>> So you should have next parameters for double glazing parameters after
>> measures or after export:
>> rf1 - interior pane front reflectance (towards the room)
>> rb1 - interior pane back reflectance (towards the exterior pane)
>> rf2 - exterior pane front reflectance (towards the interior pane)
>> rb2 - exterior pane back reflectance (towards the exterior)
>> t1 - interior pane transmittance
>> t2- exterior pane transmittance
>> r,g,b - red, green and blue color components
>> *For clear glass layers front and back reflectance are always the same
>> /
>> void BRTDfunc double_glazing
>> 10
>> if(Rdot,cr(fr(rf1_r),ft(t1_r),fr(rf2_r)),cr(fr(rb2_r),ft(t2_r),fr(rb1_r)))
>> if(Rdot,cr(fr(rf1_g),ft(t1_g),fr(rf2_g)),cr(fr(rb2_g),ft(t2_g),fr(rb1_g)))
>> if(Rdot,cr(fr(rf1_b),ft(t1_b),fr(rf2_b)),cr(fr(rb2_b),ft(t2_b),fr(rb1_b)))
>> ft(t1_r)*ft(t2_r)
>> ft(t1_g)*ft(t2_g)
>> ft(t1_b)*ft(t2_b)
>> 0 0 0
>> glaze2.cal
>>
>> 0
>> 9
>> 0 0 0
>> 0 0 0
>> 0 0 0
>> /
>>
>> In glazing definition function
>> if(Rdot,cr(fr(rf1_r),ft(t1_r),fr(rf2_r)),cr(fr(rb2_r),ft(t2_r),fr(rb1_r)))
>> means:
>> -if light is incident to the front side of the glazing then
>> reflectance is cr(fr(rf1_r),ft(t1_r),fr(rf2_r))
>> -else (light is incident to the back side) reflectance is
>> cr(fr(rb2_r),ft(t2_r),fr(rb1_r))
>>
>> Functions for double glazing reflectance and transmittance are defined
>> in *glaze2.cal *script which is provided with Radiance:
>> -cr(refl1, trans,refl2) - is reflectance distribution for double
>> glazing as function of light incident angle. refl1 is reflectance of
>> first glazing pane, refl2 of the second one, and tran1 is
>> transmittance of the first glazing pane
>> -ft(t) - transmittance distribution for single glazing as function of
>> light incident angle. For double glazing total transmittance is
>> ft(t1)*ft(t2)
>>
>> Hope this helps,
>> Marija
>> De Luminae <http://www.deluminaelab.com>
>>
>>
>>
>>
>> ------------------------------------------------------------------------
>>
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>>
>
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