Hi @Wu ,
Here’s an updated sample Grasshopper file that makes use of the latest Surface Ray Tracing component.
Hello Chris, thank you very much for your reply, I still have some questions to ask you about this plugin. I am studying the influence of different photovoltaic curtain wall component materials on the degree of outdoor reflection glare. And I have noticed that the plug-in you shared cannot change the material of the reflecting surface, but only reflects as a mirror. Then can you develop a plug-in in the outdoor environment, by changing the surface material of the building curtain wall, so as to affect the outdoor glare intensity! I really hope to get your guidance!
Hi @Wu ,
If you are studying glare, then you should be running a Radiance simulation where you set up a view that you want to evaluate glare for and assign materials to the surrounding geometry. Here is a sample for a point-in-time workflow that evaluates an image and here is a sample for for an annual glare simulation.
Hello chris,
I am very glad to get your reply. However, my research is on the effect of glass curtain walls on reflected glare in outdoor environments, not indoors. This workflow you shared is only for indoor annual glare. But what I really want to achieve is to change the material of the building curtain wall to have an impact on the outdoor reflection glare. It includes the outdoor glare area and the light intensity within the area. Still looking forward to your guidance. Thank you!
What makes you say this?
Daylight Glare Probability is just as relevant in outdoor conditions as it is for indoor conditions. It’s not like putting a pane of glass between you and the glare source suddenly makes DGP an invalid metric.
However, DGP indicators are usually for interior design, not for outdoor light pollution studies. It is designed to help design lighting systems for indoor environments to mitigate glare problems. For the study of outdoor Glare and light pollution, the more common indicators and methods include the GR value (Glare Rating) of the International Commission on Lighting (CIE), which is used to evaluate the glare in the outdoor environment.Could you build a plugin that is rated by GR?
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Ok, fair enough. If you want to use CIE Glare Index (CGI), the first sample file that I linked to for point-in-tone Image based simulation will compute GCI. You see that the HB Glare Postprocess component in that files gives you CGI as an output in addition to other glare metrics like DGP.
So you can use that for your case.
Hello Chris, after taking your advice into consideration, I simulated the outdoor glare of the glass curtain wall under outdoor conditions. As you said, HB Glare Postprocess component can get DGI, DGP, UGR, CGI and other indicators. However, the glare comfort determined by the above indicators is only applicable to the glare simulation in indoor conditions. I wonder if it is possible to add glare indicators for SGP and GR, two outdoor conditions, to this component. In addition, I have noticed that the HB Check Scene component can choose to analyze the brightness of the light source. I wonder whether the value of this brightness can be directly derived? Looking forward to your reply.
You can use falsecolor to render the HDR image, and toggle print extrama on, it will find the largest brightness region. Here is an image of facade reflection glare we rendered recently.The red region showed the reflection glare.
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Hello, thank you for your reply. So how do you quantify your glare? What evaluation index is used to evaluate the impact of light reflection on human eyes of your simulated building?
Is only my 2 cents, but many glare analysis (like Retinal Irradiance for critical impact on traffic, or potential reflected glare for residential areas, through p.e PV, Glassfasade,etc) are one of the most interesting themes wich has not been totally covered from LBT and wich had a lot of potential because is highly requested.
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I think that to evaluete the potential retinal burn, caused from reflected glare, is the simplest analysis to do, because is more a formula calculation, after perform a Irradiance Analysis with LB.
Maybe a after process component where take in account also the treshold from C. Ho would be great.
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I would ask, dear @chris, if you think is possibile to have a component that calculate the specular reflection for a point or sensor grid, caused from the sun position (Backward raytracing?), to also have the information in wich PIT and for how long, each sensor had a potential glare?
P.e. I have standards where residential, or hospital windows (on Center Point) should not be subjected to glare from a reflected source, for at least 30 minutes a day or 30 hours in a year.
Thanks and best regards
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Hi.
Given this fairly simple formula, running an annual irradiance simulation for a point and post processing that for each hour of the year and then running a moving sum every 30 minutes seems fairly straightforward.
But some knowledge of python and grasshopper data sets is required.
Regards,
LittleBuddha
Dear all,
I wonder if anybody has managed to isolate the effect of a highly reflective surface (facade, photovoltaic,…) from the overall radiation. Reflected radiation = total - direct & diffuse radiation. In theory seems quite straight forward, but in practice I see it is quite challenging. I have tried to set up my -ab to 0 to extract the direct & diffuse radiation from the reflected sum, but is not detecting the source of reflection. I would be grateful if anybody have addressed this successfully and could point me into the right direction.
Thanks
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I’ve done something similar and it worked.
Another approach is to run two Simulation, one with a reflectance set very low on the PV.
And then compare those.
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Thank you for your response! Could you please elaborate? do you mean one with little reflectance and another with the actual PV reflectance and then compare both?
When I set the -ab to 0 the irradiance results just do not make sense. So I believe that the workflow will be lower reflectance with -ab 1 and higher reflectance with -ab 2?
Thanks
Hi.
I would not change -ab to do this, as you will loose a lot of energy from bounces.
just run one with -ab over 3 with the correct reflection, and another with a very low reflection. And then compare those.
This should give you a sensible answer, if i understand what you are working on correctly.
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We usually rely Veiling Luminance where I work. you could use the 500 cd/m2 as an upper threshold.
My issue is mainly that we cannot run annually for the VL. it only works for DGP which is as you know already, suitable for indoor only.
I have been looking for the same thing for long. I use the Veiling luminance as a metric to identify glare in a PIT. However, since this cannot be processed annually, I do a raytracing study, and I add set the receptor (viewer i.e., window, or vehicle driver…) as part of the context to include it in the calculations. Then after a loooong annual run, depending on how big is the reflecting surface (e.g., facade), I pick the vectors that reaches the receptors (which could be too 100s of vectors), and I find the time and date when it occours. in the end I select few times to test VL using PIT.
It is such a long and painful process, and each assessment I seed to do alot.
I am soory I can not share an example due to company policy. but hopefully you could benifit from this methodology.
And feel free to share if any better way…
Hi Chris, thanks for your efforts here.
Apparently am not the only one nagging for a more advanced external glare components.
Since running Grid Based Veiling Luminance study similar to the DGP seems not easy to do atm. Could we improve the Raytracing component as this will help identify the times were we could test PIT?
My main issues with the RT component are:
1- 3 issues with Raytracing;
1- we cannot set up a receptor (a final receptor where reflected light is reaching). This would eleminate thouthands of unneccessary rays and make the results more readable.
2- The script draws vectors on the reflecting surface even if there is a burier blocking the ray. in other words, if the ray is directed toward the reflecting surface, and there is a building in the way (added to the context), the component is still going to drop the ray and will bounce of the context. The problem here is that we end up with endless number of rays which are not even reaching the reflecting surface.
3- if a new component can simply identify the times when the reflection reaches the receptor.
4- a limitation I struggle with is the 1 hour interval in the Sunpath, which misses thouthands of minutes in such study which could be critical, as glare may occour in between the 1 hour interval.
And a minor request if you could add on/off toggle to the component. usually if runnung annual rays, it freezes for days.
Pardon me, last question, can we run such studies using pollination?
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