# Simulate Transluscent Materials

**URL:** <https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308>\
**Category:** honeybee-legacy\
**Tags:** honeybee, ladybug\
**Created:** [July 21, 2018, 3:26pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308 "2018-07-21T15:26:40Z")\
**Posts on this page:** 13\
**Page:** 1

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**Author:** ![JimMarsh](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/jimmarsh/32/750_2.png) [@JimMarsh](https://discourse.ladybug.tools/u/JimMarsh)\
**Post date:** [July 21, 2018, 3:26pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/1 "2018-07-21T15:26:40Z")

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I haven’t found anything in the forum so far about creating custom EP and Radiance materials that simulate transluscent light-diffusing insulated panels such as [Kalwall](https://www.kalwall.com/kalwall-products/facades/walls/) or [Okalux](http://www.okaluxna.com/okalux/). Has anyone done this, or know of the reliability of the results while specifying these types of materials? I am interested in both lighting and energy performance. I’ll keep searching the internet and post any relevant info to this thread.

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**Author:** ![sarith](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/sarith/32/17511_2.png) [@sarith](https://discourse.ladybug.tools/u/sarith)\
**Post date:** [July 21, 2018, 6:44pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/2 "2018-07-21T18:44:51Z")

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The [trans material](http://radsite.lbl.gov/radiance/refer/ray.html#Trans) might be enough. If you want to get fancy, the [Complex Glazing Data Base](https://windows.lbl.gov/software/cgdb) shipped with Window 7.6 might be worth looking into (you will get BSDFs for running Lighting and Energy simulations).

I remember seeing a BSDF definition for some Okalux material either here or on the Radiance mailing list.

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**Author:** ![minggangyin](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/minggangyin/32/216_2.png) [@minggangyin](https://discourse.ladybug.tools/u/minggangyin)\
**Post date:** [July 22, 2018, 12:26am UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/3 "2018-07-22T00:26:21Z")

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@sarith By the way, could you tell me how to using BSDF file for energyplus material definition?

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**Author:** ![sarith](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/sarith/32/17511_2.png) [@sarith](https://discourse.ladybug.tools/u/sarith)\
**Post date:** [July 22, 2018, 12:18pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/4 "2018-07-22T12:18:32Z")

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@minggangyin Window exports BSDF to IDF format and the XML representation itself contains Klems data for spectrums other than visible. This has been talked about quite a bit, but I am yet to see any examples. @mostapha or @devang, any usecases that you guys are aware of ?

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**Author:** ![JimMarsh](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/jimmarsh/32/750_2.png) [@JimMarsh](https://discourse.ladybug.tools/u/JimMarsh)\
**Post date:** [July 23, 2018, 9:58pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/5 "2018-07-23T21:58:41Z")

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So, I always run into this problem where I can never find all the info I need to fill out the component. Is there a database or something that can help me find more info on translucent materials than the manufacturer offers?  
For example, Kalwall only gives me the VLT, which I assume is the diffuseTransmission? Maybe the SpecularTransmission is baked in there too? Basically my point is that I have trouble relying on manufacturer websites to find the info I need.  
 ![TransMaterial](https://discourse.ladybug.tools/uploads/default/original/2X/5/5f755345518debc079f30adbf1f62fa87d1fba84.png)

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**Author:** ![sarith](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/sarith/32/17511_2.png) [@sarith](https://discourse.ladybug.tools/u/sarith)\
**Post date:** [July 24, 2018, 7:29am UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/6 "2018-07-24T07:29:30Z")

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You are right about that information not being enough. For defining trans you’d need diffuse and specular components (openness factor). You might able to get more details from the manufacturers themselves.  
We had an undergrad student who worked with Kalwall material and was using an empirical definition to define the material: [http://diva4rhino.com/forum/topics/kalwall-material](http://diva4rhino.com/forum/topics/kalwall-material) . With regards to databases, [IGDB deals only with specular glazings](https://windows.lbl.gov/software/igdb). CGDB, as the name suggests, has more complex materials. Andy McNeil’s Three Phase tutorial has an example of how to extract materials from CGDB via Window.

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**Author:** ![JimMarsh](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/jimmarsh/32/750_2.png) [@JimMarsh](https://discourse.ladybug.tools/u/JimMarsh)\
**Post date:** [July 24, 2018, 12:56pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/7 "2018-07-24T12:56:37Z")

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In that post, there is a file path to c:\DIVA\Thermal\Rhino\04\_material\_construction.idf. What is the comparable file path for Lb/Hb that material definitions can get pasted into?  
EDIT: A search of my C Drive for “.idf” pulled up userCustomEPLibrary.idf which is in C:\ladybug. I’ve run into this problem before, but when I open that .idf with Wordpad it only says “!Honeybee custom EnergyPlus library” and I never was able to figure out where EP Materials come from if that file is completely empty of material definitions.

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**Author:** ![mostapha](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/mostapha/32/15244_2.png) [@mostapha](https://discourse.ladybug.tools/u/mostapha)\
**Post date:** [July 24, 2018, 9:02pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/8 "2018-07-24T21:02:18Z")

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> [@JimMarsh](#):
>
> A search of my C Drive for “.idf” pulled up userCustomEPLibrary.idf which is in C:\ladybug. I’ve run into this problem before, but when I open that .idf with Wordpad it only says “!Honeybee custom EnergyPlus library” and I never was able to figure out where EP Materials come from if that file is completely empty of material definitions.

`userCustomEPLibrary.idf` is for adding new/custom EnergyPlus objects to Honeybee. Default constructions, materials and schedules are imported from `OpenStudioMasterTemplate.idf`.

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**Author:** ![JimMarsh](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/jimmarsh/32/750_2.png) [@JimMarsh](https://discourse.ladybug.tools/u/JimMarsh)\
**Post date:** [July 25, 2018, 1:23pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/9 "2018-07-25T13:23:25Z")

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I found [this other post](https://www.grasshopper3d.com/group/ladybug/forum/topics/how-to-get-rad-ep-materials?page=1&commentId=2985220%3AComment%3A1324068&x=1#2985220Comment1324068) you had that suggests to write custom materials into userCustomEPlibrary.idf.

> I still suggest you to add your material to userCustomEPLibrary.idf and not OpenStudioMasterTemplate.idf, as Honeybee overwrites OpenStudioMasterTemplate.idf once there is an updated version.

Is it as simple as pasting the bolded part of this post shared above into that file?

> I actually did this for the presentation of DIVA-2.0 back in 2011 (see the presentation). The material I used for that is something like the below,  
> **WindowMaterial:Glazing, glazed\_element, !- Kalwall**  
> **SpectralAverage, !- Optical data type {SpectralAverage or Spectral}**  
> **, !- Name of spectral data set when Optical Data Type = Spectral**  
> **0.1, !- Thickness {m}**  
> **.2, !- Solar transmittance at normal incidence**  
> **.1, !- Solar reflectance at normal incidence: front side**  
> **.1, !- Solar reflectance at normal incidence: back side**  
> **.2, !- Visible transmittance at normal incidence**  
> **.15, !- Visible reflectance at normal incidence: front side**  
> **.15, !- Visible reflectance at normal incidence: back side**  
> **.0, !- IR transmittance at normal incidence**  
> **.84, !- IR emissivity: front side**  
> **.84, !- IR emissivity: back side**  
> **0.0284, !- Conductivity {W/m-K}**  
> **1; !- Dirt Correction Factor for Solar and Visible Transmittance**  
> Which should give a US R-Value of 20, though do check my numbers. It then gets applied to an EnergyPlus construction like so,  
> **Construction,**  
> **kalwall, !- Name**  
> **glazed\_element; !- Material**

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<div class="post-metadata">

**Author:** ![mostapha](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/mostapha/32/15244_2.png) [@mostapha](https://discourse.ladybug.tools/u/mostapha)\
**Post date:** [July 26, 2018, 1:31am UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/10 "2018-07-26T01:31:17Z")

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> [@JimMarsh](#):
>
> Is it as simple as pasting the bolded part of this post shared above into that file?

Yes. I suggest to add a new line at the end of every `,`.

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<div class="post-metadata">

**Author:** ![JimMarsh](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/jimmarsh/32/750_2.png) [@JimMarsh](https://discourse.ladybug.tools/u/JimMarsh)\
**Post date:** [July 26, 2018, 5:41pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/11 "2018-07-26T17:41:12Z")

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Awesome, Kalwall is now importing in gh!  
What is the respective file for adding custom Radiance materials? I successfully made a test material months ago through the addToLibrary Radiance component, but I have never been able to find that text file it lives in.

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**Author:** ![devang](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/devang/32/21620_2.png) [@devang](https://discourse.ladybug.tools/u/devang)\
**Post date:** [August 5, 2018, 12:51pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/12 "2018-08-05T12:51:06Z")

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Split this topic on August 5, 2018, 12:51pm UTC

A post was split to a new topic: [Import WINDOW IDF Report Issue](https://discourse.ladybug.tools/t/import-window-idf-report-issue/3387)

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**Author:** ![Aliarch](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/aliarch/32/39969_2.png) [@Aliarch](https://discourse.ladybug.tools/u/Aliarch)\
**Post date:** [April 6, 2020, 2:04pm UTC](https://discourse.ladybug.tools/t/simulate-transluscent-materials/3308/13 "2020-04-06T14:04:27Z")

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hi Mr sarith

I want to simulate crystal glass that absorbs and concentrates light.  
Do you have the file bsdf?