Diffusive laminated material and fritting

Dear List,

I am currently trying to simulate a laminated build up with diffusive
interlayer. To get accurate results I turned to Optics5 to build the
laminate. I would expect that the right kind of material definition
would be a trans or transdata, but Optics keep on returning glass and 2
BRTDfunc (front face and back face). As per my understanding the
BRTDfunc will only affect the front and back reflectance, and contains
no information about diffusion.
As I am interested in assessing the effects of different levels of
diffusion in the interlayer, I was wondering if any of you could suggest
what would be the most reliable approach.

Also I was wondering how people go about simulating fritting; if the
glass is far enough to make the fritting not visible, is it common
practice reducing the transmissivity by the percentage cover of the
fritting or there are more sophisticated (and accurate) approaches?

Thanks in advance for the help,

Giovanni

////////////////////////////////////////////////
Giovanni Betti
Environmental Design Analyst

Hi Giovanni,

I will give a short answer and then try to follow-up later with a longer explanation. Regarding the diffusing interlayer, as I recall Optics 5 is not really set up to deal with diffusing materials (unless this has changed recently). Regardless, any material definition exported to Radiance format will be in the form of three materials: a glass definition and a front and back side BRTDfunc. Note however that the BRTDfunc (unless this has been changed) is a very simplified material definition that is not set up to account for angular variation. There are a couple of options to convert Radiance output from Optics 5 to something more useful: A) optics2rad or B) glaze. These are both scripts that come with the standard Radiance distribution.

I am not sure what to suggest for how to manage the diffuse component. This can probably be incorporated into a BRTDfunc definition. Regarding the fritting, I agree with your presumption that if you are any reasonable distance from the building then the individual makeup (lines, dots, whatever), will disappear in most cases. It is possible to build up frit glass definitions (based on percent coverage) using the glaze script.

Regards,

-Jack de Valpine

···

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

On 10/28/2010 7:49 AM, Giovanni Betti wrote:

Dear List,

I am currently trying to simulate a laminated build up with diffusive
interlayer. To get accurate results I turned to Optics5 to build the
laminate. I would expect that the right kind of material definition
would be a trans or transdata, but Optics keep on returning glass and 2
BRTDfunc (front face and back face). As per my understanding the
BRTDfunc will only affect the front and back reflectance, and contains
no information about diffusion.
As I am interested in assessing the effects of different levels of
diffusion in the interlayer, I was wondering if any of you could suggest
what would be the most reliable approach.

Also I was wondering how people go about simulating fritting; if the
glass is far enough to make the fritting not visible, is it common
practice reducing the transmissivity by the percentage cover of the
fritting or there are more sophisticated (and accurate) approaches?

Thanks in advance for the help,

Giovanni

////////////////////////////////////////////////
Giovanni Betti
Environmental Design Analyst

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

Thanks Jack,

I have done some more reading on the mailing list and found a few useful
posts describing opt2rad and glaze.
Both seem really useful, although glaze seems likely the most
interesting option because (if I understand correctly) allows for frit
and angular dependencies in transmission/reflection.

Unfortunately I am using radiance on windows using the Ming-w compiled
version and I do not find the files in my bin or lib folder (but I find
glaze2.cal). Is there a version of these available for windows?

Also Glaze supports only two glass panes with an interlayer or can cope
with three-ply build ups?

Thanks again,

G

···

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jack
de Valpine
Sent: 28 October 2010 14:10
To: Radiance general discussion
Subject: Re: [Radiance-general] Diffusive laminated material and
fritting

Hi Giovanni,

I will give a short answer and then try to follow-up later with a longer

explanation. Regarding the diffusing interlayer, as I recall Optics 5 is

not really set up to deal with diffusing materials (unless this has
changed recently). Regardless, any material definition exported to
Radiance format will be in the form of three materials: a glass
definition and a front and back side BRTDfunc. Note however that the
BRTDfunc (unless this has been changed) is a very simplified material
definition that is not set up to account for angular variation. There
are a couple of options to convert Radiance output from Optics 5 to
something more useful: A) optics2rad or B) glaze. These are both scripts

that come with the standard Radiance distribution.

I am not sure what to suggest for how to manage the diffuse component.
This can probably be incorporated into a BRTDfunc definition. Regarding
the fritting, I agree with your presumption that if you are any
reasonable distance from the building then the individual makeup (lines,

dots, whatever), will disappear in most cases. It is possible to build
up frit glass definitions (based on percent coverage) using the glaze
script.

Regards,

-Jack de Valpine

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

On 10/28/2010 7:49 AM, Giovanni Betti wrote:

Dear List,

I am currently trying to simulate a laminated build up with diffusive
interlayer. To get accurate results I turned to Optics5 to build the
laminate. I would expect that the right kind of material definition
would be a trans or transdata, but Optics keep on returning glass and

2

BRTDfunc (front face and back face). As per my understanding the
BRTDfunc will only affect the front and back reflectance, and contains
no information about diffusion.
As I am interested in assessing the effects of different levels of
diffusion in the interlayer, I was wondering if any of you could

suggest

what would be the most reliable approach.

Also I was wondering how people go about simulating fritting; if the
glass is far enough to make the fritting not visible, is it common
practice reducing the transmissivity by the percentage cover of the
fritting or there are more sophisticated (and accurate) approaches?

Thanks in advance for the help,

Giovanni

////////////////////////////////////////////////
Giovanni Betti
Environmental Design Analyst

_______________________________________________
Radiance-general mailing list
[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

Hi Giovanni,

The glaze script supports an IGU with (2) glass layers only. As I understand from Greg who developed this for us originally, the math starts to get a lot more complicated with a 3rd glass layer. This does not mean that it cannot be done but it would need to be implemented. I guess there are a few things to understand with the glaze script. What you want to get out of Optics 5 is Radiance material exports NOT for the full IGU makeup but instead for each layer of the makeup. Then you can use the transmittance and reflectance data for the exported materials to build material definitions for 2 layer glazing makeups where a coating can be allocated to one surface and a frit to another (note you cannot have both frit and coating applied to the same surface because we do not know how to characterized that). Regarding the interlayer, I think what I would suggest is that (assuming a clear interlayer) is to make up the composite in Optics 5 (eg 2 glass materials with an interlayer) and then export this as a glass layer.

Regarding Ming-w, I am sorry that I am not really familiar with compiling or running Radiance in this way, so I do not really know why things might not be found. Note that glaze is a shell script like falsecolor for example, so if you have falsecolor then glaze "should" be available and work...

-Jack

PS: you could also take a look at my talk at the 2009(?) Radiance Workshop at Harvard, which talks a bit about glaze and some other tools.

···

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

On 10/28/2010 9:44 AM, Giovanni Betti wrote:

Thanks Jack,

I have done some more reading on the mailing list and found a few useful
posts describing opt2rad and glaze.
Both seem really useful, although glaze seems likely the most
interesting option because (if I understand correctly) allows for frit
and angular dependencies in transmission/reflection.

Unfortunately I am using radiance on windows using the Ming-w compiled
version and I do not find the files in my bin or lib folder (but I find
glaze2.cal). Is there a version of these available for windows?

Also Glaze supports only two glass panes with an interlayer or can cope
with three-ply build ups?

Thanks again,

G

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jack
de Valpine
Sent: 28 October 2010 14:10
To: Radiance general discussion
Subject: Re: [Radiance-general] Diffusive laminated material and
fritting

Hi Giovanni,

I will give a short answer and then try to follow-up later with a longer

explanation. Regarding the diffusing interlayer, as I recall Optics 5 is

not really set up to deal with diffusing materials (unless this has
changed recently). Regardless, any material definition exported to
Radiance format will be in the form of three materials: a glass
definition and a front and back side BRTDfunc. Note however that the
BRTDfunc (unless this has been changed) is a very simplified material
definition that is not set up to account for angular variation. There
are a couple of options to convert Radiance output from Optics 5 to
something more useful: A) optics2rad or B) glaze. These are both scripts

that come with the standard Radiance distribution.

I am not sure what to suggest for how to manage the diffuse component.
This can probably be incorporated into a BRTDfunc definition. Regarding
the fritting, I agree with your presumption that if you are any
reasonable distance from the building then the individual makeup (lines,

dots, whatever), will disappear in most cases. It is possible to build
up frit glass definitions (based on percent coverage) using the glaze
script.

Regards,

-Jack de Valpine

One other item to note here. Just to be clear although we are talking about real glazing systems with multiple physical layers in their makeups, for simulation purposes the behavior is managed through the material definition as applied to ONE layer of geometry representing the glazing (eg glazing is represented as a surface).

-Jack

···

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

On 10/28/2010 12:09 PM, Jack de Valpine wrote:

Hi Giovanni,

The glaze script supports an IGU with (2) glass layers only. As I understand from Greg who developed this for us originally, the math starts to get a lot more complicated with a 3rd glass layer. This does not mean that it cannot be done but it would need to be implemented. I guess there are a few things to understand with the glaze script. What you want to get out of Optics 5 is Radiance material exports NOT for the full IGU makeup but instead for each layer of the makeup. Then you can use the transmittance and reflectance data for the exported materials to build material definitions for 2 layer glazing makeups where a coating can be allocated to one surface and a frit to another (note you cannot have both frit and coating applied to the same surface because we do not know how to characterized that). Regarding the interlayer, I think what I would suggest is that (assuming a clear interlayer) is to make up the composite in Optics 5 (eg 2 glass materials with an interlayer) and then export this as a glass layer.

Regarding Ming-w, I am sorry that I am not really familiar with compiling or running Radiance in this way, so I do not really know why things might not be found. Note that glaze is a shell script like falsecolor for example, so if you have falsecolor then glaze "should" be available and work...

-Jack

PS: you could also take a look at my talk at the 2009(?) Radiance Workshop at Harvard, which talks a bit about glaze and some other tools.