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I am trying to model a Diffuser for Daylight Illumination using OpenStudio and Radiance.

asked 2015-06-24 00:08:03 -0500

SIMVRK's avatar

updated 2015-06-24 06:52:40 -0500

An existing Office in the Institute where I study has a hole in the roof. I am modeling this space with OpenStudio to evaluate the natural illumination and the proposal of a Diffuser to favor natural lighting in a specific zone.

I want to model two different diffusers (Ring diffuser and curved diffuser).

A post on the forum indicates that SketchUp does not accept curved diffusers But when I want to insert a form or an object, Sketch Up does recognize it if it is group or block.

So my questions are: 1. Is correct to model the circular hole with a circular windows? 2. Is correct to model the two types of Diffuser using “shading surface”? Or it should be modeled as an “Interior Partition Surface Group” component, considering that I need to control the absorptance, reflectance and transmittance?

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answered 2015-06-24 17:44:00 -0500

It's difficult to say what the best approach is for your situation here, as I cannot tell what your diffusers look like, what they are made of, or how you expect them to work. In a general sense however, it is true (as stated in the previous post you mention) that SketchUp and OpenStudio (and EnergyPlus and even Radiance to an extent) do not support true curves (e.g. cylinders, discs, rings). These shapes are approximated via segmentation, and you should use as few segments as needed to suggest the behavior of the diffuser design.

As far as modeling light-blocking or -redirecting "bits" in the interior space, from a Radiance simulation perspective, I would recommend using interior partition surfaces. As these are only translated to Radiance, you can use as many surfaces to represent your design as needed.

You also mention the need to translate transmittance; presumably your diffuser has transparent or translucent elements to it? Currently the Radiance translator assumes shading and interior partition surfaces are opaque, and subsurfaces are not handled. We can certainly add support for this, it's merely a question of how best to approach it. I'm hoping others on the team can weigh in here with thoughts on how best to handle this.

In the meantime, could you flesh out your question, perhaps with an image or sketch of the diffuser design(s)? That would help guide us on the path to the best solution from the model/translator side of things.

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answered 2015-07-08 02:39:42 -0500

SIMVRK's avatar

I discarded the option of modeling a diffuser with curvatures. In the following figures are shown the diffusers i was trying to model:

In real life the hole in the ceiling of the room is circular, but for simulations I decided to switch it for a square hole with same area, as shown in the following figure:

Finally I modeled a simple square diffuser with a planar surface constructed with "Partition Interior Surface Group" and I could assign parameters of absorptance and reflectance, as shown in the following figure:

Thanks for the suggestions and help.

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Glad you got this working! All of your geometry simplifications are perfectly valid and will result in useful data. My next question for you is, how are you modeling the diffuser at the ceiling? What object type is that (I assume it's a skylight), and what is the material at the ceiling? A diffusing panel? Glass?

rpg777's avatar rpg777  ( 2015-07-08 10:45:45 -0500 )edit

answered 2019-12-03 09:07:26 -0500

NunoSaraiva's avatar

updated 2019-12-03 09:07:58 -0500

I have a similar question related to the type of material. I am trying to find methodologies to model the material similar to interior wait curtains or diffusing panels like:

image description

How can we define the level of diffusing "intensity"? Or is it only possible to work with transmittance and reflectance? My model is predicting high values of illuminance and I would like to diffuse the solar rays.

I was checking "glaze" script but, from my understanding, it only includes the inner ray reflectances within a glazing system.

May I ask you what type of material did you use?

Thank you in advance

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Asked: 2015-06-24 00:08:03 -0500

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Last updated: Dec 03 '19