Radiance Trans Material question

Hello all,

I’m trying to work with Radiance Trans Material but I’m having little trouble understading how it works.

I’ve read the document “‘Trans Materials –Modeling and Specifying a Next Generation” by David Mead (http://radiance-online.org/community/workshops/2010-freiburg/PDF/Da…). It was very helpful but still I’m not confident with this kind of material.

I’ll explain shortly my design.

I’m trying to bring natural light deeper into a generic building. To do so, I want to use a system in which a mirror outside the facade directs the sunlight through a horizontal shaft composed of mirrors on the upper part and on the sides with a “membrane” on the lower side defined as a “Trans Material”.

My goal is to obtain an effect like the one showed in the attached photo. It’s a skylight make of opaque semi-transparent plastic.

Does anyone know any good parameter to simulate that?

I’m attaching also a little section and the gh file.

Thanks everybody for your help.


Diffusore.gh (584 KB)


I’m not clear about your question. Do you have difficulties creating the materials or do you want to know about Radiance parameters to see the effect of multiple bounces.

For the material your best bet is to find the values from a measurement. Is there a company that you’re using their material. They might have an accurate measurement or a BSDF file for their product.

For the second part of the question check Andy’s approach to model a light-pipe using 3Phase method. It’s not possible to run a 3-Phase daylight analysis with Honeybee at this point. :expressionless: