Hi,
I've searched list's archive to find out some data related to prismatic
glazing simulation in Radiance. Here are some related questions.
First question is where to find valid optical and geometrical data related
to prismatic glazings. On various manufacturers' sites, like Siteco or
Inglas, there is only some descriptive info ,without any data useful for
simulations. I've found that some measuremens have been taken by Martin
Moeck few years ago for Siteco glazings. Are results available somewhere?
My idea is to use these glazings in light pipe simulation, on top and/or
bottom of pipe for light redirection, so I would go with pmap approach.
Since prism material calculation is not implemented in pmap, I suppose some
geometrical definition of glazing would be necessary with usage of
dielectric or interface material and then simulation with pmap.
Does anyone has some experience with geometrical definition and how much
accurate it should be (beside examples in Ronald Schregle thesis)?
In Lars mail
http://www.radiance-online.org/pipermail/radiance-general/2009-February/005793.htmlhe
put some questions related to Fresnel diffusers simulation. Lars, have
you succeeded in these simulations? Can you share with us your experience?
Beside pmap, would be rtcontrib be able to calculate light distribution from
light pipes, with new 3-phases method. In that case how to calculate and
define BTDF for complete sun pipe system (collector + pipe + diffuser)?
Lots of questions, and don't know where to go next. So any info would be
useful.
Marija,
De Luminae
www.deluminaelab.com
Hi Marija,
First question is where to find valid optical and geometrical data related
to prismatic glazings. On various manufacturers' sites, like Siteco or
Inglas, there is only some descriptive info ,without any data useful for
simulations. I've found that some measuremens have been taken by Martin
Moeck few years ago for Siteco glazings. Are results available somewhere?
I can't answer any of your technical questions, but I spoke to a Siteco
rep a few months ago. I ask her about Radiance cal files for their fancy
glazing. Her reply was that Siteco do have Radiance descriptions of their advances glazing products, but are 'very reluctant' to give them to anybody.
Her explanation to this was that in order to get that advanced glazing working correctly, the optimum orientation of the panels needs to be determined based on window orientation and slope. It is quite easy to get this wrong, in which case the product would actually reduce the daylight rather than improving it. Subsequently, Siteco's product would appear to be rubbish.
With this in mind, Siteco do free-of-charge calculations when you decide to go with one of their products, making sure that if someone gets it wrong, it'll be them.
Cheers
Axel
Hi Marija!
First question is where to find valid optical and geometrical data
related to prismatic glazings. On various manufacturers' sites, like
Siteco or Inglas, there is only some descriptive info ,without any data
useful for simulations. I've found that some measuremens have been taken
by Martin Moeck few years ago for Siteco glazings. Are results available
somewhere?
I am not aware of publicly available measurement data. So probably one should start with getting some relieable data measured by one of the labs offering such service.
My idea is to use these glazings in light pipe simulation, on top and/or
bottom of pipe for light redirection, so I would go with pmap approach.
Since prism material calculation is not implemented in pmap, I suppose
some geometrical definition of glazing would be necessary with usage of
dielectric or interface material and then simulation with pmap.
Does anyone has some experience with geometrical definition and how much
accurate it should be (beside examples in Ronald Schregle thesis)?
I have not done a validation in the meaning of comparing with analytical and measurement results. However this is one of the core use cases for the pmap extension. The pmap approach would be by doing an accurate geometrical description and have mkpmap do the forward tracing. As far as I understand you are interested in the angular-dependent reflectance of the prism sheet in you case, so maybe using a good fit to measurement data would also be an option (in that case with "classic" Radiance).
he put some questions related to Fresnel diffusers simulation. Lars,
have you succeeded in these simulations? Can you share with us your
experience?
You can do all this, but be aware that using the pmap means quite a lot of fine-tuning. I have modeled light ducts with prism sheets, and got some result, but as I said I have not been able to validate it yet against measured data. In my opinion doing such comparisions is the critical task...
Cheers, Lars.