Hi everybody,
I am performing a point-in-time image simulation to assess glare in some critical open office positions.
I have run a simulation with no blinds first and I get DGP=1. So I carried out an parametric study with a range of different roller shades varying the Specular transmision, diffuse transmision and the reflectance of the trans material definition to obtein the best balance between a low glare index and a high illuminance (measured as DA in a sensor right in the workplane).
I obtain that White roller blinds with an openness factor of 1% perform the best. But the literature says that white blind rollers will create high contrast in the visual field and not remove the risk of glare but increase it, so instead it is recommended to use more grey colors for this purpose. I wonder If any of you have tried to perform any similar study before and if these results are trustable.
I hope you’re doing well. I’m currently working on my thesis, which explores the effect of different fabric Openness Factors on daylight and energy efficiency. I wanted to ask if the “OF” in the algorithm shown in the attached screenshot refers to the Openness Factor. If that’s the case, I would like to ask a couple of additional questions.
I am Master of Architecture student at SIUC. currently working on my thesis regarding the effect of openness factor (OF) of fabrics in kinetic facade systems, in relation to energy efficiency and daylight performance. I am encountering some difficulties integrating the OF into my simulation algorithm. The components I have used so far do not seem to directly accept the OF as an input. I was wondering if you might have a sample file or guidance that could assist me in setting up this simulation. Additionally, if there is an alternative method or component that allows for the direct input of OF, I would greatly appreciate any advice or suggestions. Thank you for your time and help.
The way Radiance and Energy Plus approach the OF is different.
The OF will have several impact: energy, thermal comfort, glare, daylight availability,…
In terms of energy and thermal comfort, Energy Plus accepts the following inputs
Permeability is equivalent to OF in energy simulations. If you want to modify the distance from the window you would have to do it manually as I am showing in the screenshot, since this is not an input available, in any case, this normally doesn’t affect the results much.
In terms of glare, DGP works best with HB HDR image, annual DGP will not considered this openness factor since the way it is calculated (simplification) differs from the image-based (point in time) calculation. So for DGP I will recommend you to select a certain points in time that could be representative for that position and view direction. You can have a good guess when this will most likely occur by looking at the annual DGP, but this does not necesarily have to match for the reasons I explained above.
In HB Radiance spec trans (Tv, n-n) is similar to the openness factor, that is the fraction of the translucent material that allows for direct light transmission. The small differences between the two are mainly originated from the fabric filaments. The openness factor will be something like the geometric definition and the normal transmittance will be the actual measured fraction.
Thank you so much for the clarification! This is incredibly helpful and will definitely help me move forward. Do you have any suggestions for calculating ASE and sDA metrics as well?
I have a question regarding modeling Roller shades in HB radiance. After setting up the HB-translucent modifier, how I can integrate this into my Honeybee model so I can use it for my Daylighting analysis? Shall I use ModifierSets? I would be grateful for any advise or any sample workflow.
Hi @Mojdehsbt,
Like almost everything in Grasshopper and Ladybug there are several ways to address this.
The way I have done it is connecting the trans modifier to the HB Shade component and this one to the HB Model like so:
Thank you for your reply and the explanation.
I wanted to ask if there is a way that the Roller shades would be modeled in Grasshopper (Like the workflow for energy simulation) instead of modeling them in Rhino and assigning a geometry to them in Grasshopper?
Hi @Mojdehsbt, you could always do an offset of the window geometry and set the distance from the window as your offset distance. This could be easily done in Grasshopper with the move component and the window normal vector, this way you would not need to model it in Rhino. But this is more of a Grashopper question than Ladybug.
