[Radiance-general] modeling an insulating glass with an integrated capillary slab

[Valeria De Giuli]

Thank you all! Yes, the product I have to model is the Kapilux. I'm going through the report of Christoph and Marilyne: I think that product is very similar to the one I have to simulate. I have decided to model it following the second option (trans 16%), using the diffuse-diffuse transmittance instead of the direct normal hemispherical (30% in my case). I then put the same values for the other parameters. Do you think it is correct?
Thanks a lot,
Valeria


Il giorno 28/apr/2012, alle ore 04:28, Greg Ward ha scritto:

> Is this similar to the translucent panel modeled by Christoph Reinhart and Marilyne Andersen in the following paper?
> 
> 	http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc48165/nrcc48165.pdf
> 
> I believe they developed a Radiance description for it.
> 
> Cheers,
> -Greg
> 
>> From: Andy McNeil <amcneil at lbl.gov>
>> Date: April 27, 2012 3:42:25 PM PDT
>> 
>> It's really tough to say without knowing what they mean by direct and diffuse transmission.  From their website I understand that by "direct" they mean normal incidence direct-hemispherical transmission and by "diffuse" they mean hemispherical-hemispherical transmission.  I would suggest setting Td to 30% and know that for non-normal incidence angles you will over estimate overall transmission.
>> 
>> This product, with it's capillary tubes and diffusing papers, is a perfect example of a system that should be modeled with a BSDF.  Unfortunately your options for BSDF characterization are murky at best right now.
>> 
>> Andy
>> 
>> On Apr 27, 2012, at 2:47 PM, Valeria De Giuli wrote:
>> 
>>> Thank you Andy, this is a quick and useful widget, however in this case I have only direct and diffuse visible transmission, therefore I can only assign the diffuse transmission. Am I right?
>>> Thanks,
>>> Valeria
>>> 
>>> Il giorno 27/apr/2012, alle ore 23:31, Andy McNeil ha scritto:
>>> 
>>>> Hi Valeria,
>>>> Trans is a quick and easy way to model this type of glazing.  
>>>> You can use this widget to generate a trans material definition by entering your transmission and reflection parameters: http://gaia.lbl.gov/people/andy/public/transwidget/
>>>> 
>>>> However trans does not account for Fresnel effects that reduce transmission of glass at non-normal incidence angles (http://en.wikipedia.org/wiki/File:Amptitude_Ratios_air_to_glass.JPG).  So treat trans results with some degree of caution.
>>>> 
>>>> If you want to include fresnell effects and diffusion, you might consider use a glass surface and a trans surface one in front of the other.  Or you could generate a BSDF and use the new BSDF material.
>>>> 
>>>> Hope this helps,
>>>> Andy
>>>> 
>>>> 
>>>> On Apr 27, 2012, at 1:34 PM, Valeria De Giuli wrote:
>>>> 
>>>>> Dear all,
>>>>> I have to model a two-pane glass make up with a selective 6mm outer pane with an integrated capillary slab (it is called kapilux), white tinted. The obtained effect is a uniform and diffuse light transmittance. The only technical data that I have are: 30% of direct visible transmittance  and 15% of diffuse visible transmittance. I think I should model it with "trans" material, but I don't know which parameters I have to use. Does anybody has an idea?
>>>>> Thanks in advance. Best regards,
>>>>> Valeria
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