Model a Double glazing window

radiance-general
1

Hi Every one,

I want to model a Double glazing window which contains glasses with different transmittances. I did the following

1. window.rad -- included the properties of materials such as window frame, glass1 and glass 2
2. glass.rad -- position of glasses using genbox
3. frame.rad -- position of frame using genbox

then made octree of altogether.

Please let me know if this is the right way or if not please suggest a better one.

Best Regards,
Raghu

2

Hi Raghu,

Here are a couple of things to think about.

MODEL GEOMETRY
Based on your description, I am guessing that you are using genbox to model each sheet of glass in your insulating glass unit. The radiance materials that can be used to describe glass, such as "glass" and "brtdfunc" are designed to be applied to a surface as opposed to a volume. Using genbox will give you a volume, applying a "glass" material with a specific transmittance to that volume will not give you the correct resulting transmittance because rays are going through two pieces of geometry. In order to get the correct transmittance for a given glass material you would need to use a single surface to describe the geometry.

GLASS MATERIALS
If all you care about is transmittance through a insulating glass unit composed of two layers of glass, there are a variety of ways to to come up with a material description. The resulting transmittance of a specific makeup should either be available from a manufacturer or can be calculated with an application like Windows or Optics (both available from LBNL). Note that for the glass material type transmittance needs to be transformed to the Radiance term for transmissivity. If you also need to more carefully account for reflectance for such a glazing unit, assuming you are using Radiance on Linux, then you can use the "glaze" script that comes with Radiance. To learn more about how to use the script, you can check out my blog post:

    model | simulate | visualize: Glass in Radiance

Best,

-Jack de Valpine,
Visarc Inc

···

On 12/18/2015 12:34 PM, raghuram kalyanam wrote:

Hi Every one,

I want to model a Double glazing window which contains glasses with different transmittances. I did the following

1. window.rad -- included the properties of materials such as window frame, glass1 and glass 2
2. glass.rad -- position of glasses using genbox
3. frame.rad -- position of frame using genbox

then made octree of altogether.

Please let me know if this is the right way or if not please suggest a better one.

Best Regards,
Raghu

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[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

3

Hi Jack,

Wow this what exactly I am looking for. Thank you very much. I have another question. Is there a better way to do geometric modeling and then export into radiance? as it seems a bit cumbersome to model in command prompt in my Mac and then check its geometry every time making an octree.

Best Regards,
Raghu

···

On Dec 18, 2015, at 10:39 PM, Jack de Valpine <[email protected]> wrote:

Hi Raghu,

Here are a couple of things to think about.

MODEL GEOMETRY
Based on your description, I am guessing that you are using genbox to model each sheet of glass in your insulating glass unit. The radiance materials that can be used to describe glass, such as "glass" and "brtdfunc" are designed to be applied to a surface as opposed to a volume. Using genbox will give you a volume, applying a "glass" material with a specific transmittance to that volume will not give you the correct resulting transmittance because rays are going through two pieces of geometry. In order to get the correct transmittance for a given glass material you would need to use a single surface to describe the geometry.

GLASS MATERIALS
If all you care about is transmittance through a insulating glass unit composed of two layers of glass, there are a variety of ways to to come up with a material description. The resulting transmittance of a specific makeup should either be available from a manufacturer or can be calculated with an application like Windows or Optics (both available from LBNL). Note that for the glass material type transmittance needs to be transformed to the Radiance term for transmissivity. If you also need to more carefully account for reflectance for such a glazing unit, assuming you are using Radiance on Linux, then you can use the "glaze" script that comes with Radiance. To learn more about how to use the script, you can check out my blog post:
model | simulate | visualize: Glass in Radiance
Best,

-Jack de Valpine,
Visarc Inc

On 12/18/2015 12:34 PM, raghuram kalyanam wrote:

Hi Every one,

I want to model a Double glazing window which contains glasses with different transmittances. I did the following

1. window.rad -- included the properties of materials such as window frame, glass1 and glass 2
2. glass.rad -- position of glasses using genbox
3. frame.rad -- position of frame using genbox

then made octree of altogether.

Please let me know if this is the right way or if not please suggest a better one.

Best Regards,
Raghu

_______________________________________________
Radiance-general mailing list
[email protected] <mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

4

OH MY GOD, YES. There are lots of CAD tools out there, which I'm sure you're familiar with. But there are also some CAD-to-Radiance geometry translators out there. Jack has some great workflows for this, if you use Revit or whatever BIM mess you're lashed to. Lots of people here use Rhino for geometry, and get into Radiance by way of the Alias-Wavefront (.obj) format. Again others here will have some workflow ideas. The project I work on (OpenStudio) can take a SketchUp model and translate it to Radiance format (and actually do a hell of a lot of setup for you if you're doing 3-phase daylight coefficient-type modeling with Radiance, but those models are biased toward energy modeling tools.

If you simply want to make a nice model in a free cad tool and export exactly what you've modeled into pure Radiance input, I'd highly recommend you look at SketchUp for modeling, and Groundhog and/or su2rad for the geometry translation:

http://igd-labs.github.io/Groundhog/
https://code.google.com/p/su2rad/wiki/Su2radIntro

···

On 12/21/15, 6:45 AM, "Raghuram Kalyanam" <[email protected]<mailto:[email protected]>> wrote:
I have another question. Is there a better way to do geometric modeling and then export into radiance? as it seems a bit cumbersome to model in command prompt in my Mac and then check its geometry every time making an octree.

Best Regards,
Raghu

5

Hi Raghu,

Yes, basically what Rob said.... Depending on your desire for figuring workflow (eg getting geometry from on format to one suitable for use in Radiance), there are lots of ways to go:

    Autodesk based products - Autocad, Revit, Max, Maya....
    Rhino
    Sketchup
    Blender

There are probably others I am not thinking of. Probably the safest intermediate geometry format is Alias/Wavefront (.obj) as Rob mentioned. Radiance has tools (obj2rad and obj2mesh) that can handle translating this format into its native geometry format.

Best,

-Jack

···

On 12/21/2015 10:28 AM, Guglielmetti, Robert wrote:

OH MY GOD, YES. There are lots of CAD tools out there, which I'm sure you're familiar with. But there are also some CAD-to-Radiance geometry translators out there. Jack has some great workflows for this, if you use Revit or whatever BIM mess you're lashed to. Lots of people here use Rhino for geometry, and get into Radiance by way of the Alias-Wavefront (.obj) format. Again others here will have some workflow ideas. The project I work on (OpenStudio) can take a SketchUp model and translate it to Radiance format (and actually do a hell of a lot of setup for you if you're doing 3-phase daylight coefficient-type modeling with Radiance, but those models are biased toward energy modeling tools.

If you simply want to make a nice model in a free cad tool and export exactly what you've modeled into pure Radiance input, I'd highly recommend you look at SketchUp for modeling, and Groundhog and/or su2rad for the geometry translation:

http://igd-labs.github.io/Groundhog/
https://code.google.com/p/su2rad/wiki/Su2radIntro

On 12/21/15, 6:45 AM, "Raghuram Kalyanam" <[email protected]<mailto:[email protected]>> wrote:
  I have another question. Is there a better way to do geometric modeling and then export into radiance? as it seems a bit cumbersome to model in command prompt in my Mac and then check its geometry every time making an octree.

Best Regards,
Raghu

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general