Hi everyone!!
I’m conducting research to understand how different tools analyze and return results related to daylight. I’ve performed three analyses:
Point in time illuminance using Climate Studio in Rhino
Point in time illuminance using Climate Studio in Grasshopper
Point in time illuminance using Honeybee-Radiance in Grasshopper
The problem is that the results (mainly the numerical value rather than the graphical output) from the first two analyses (both using Climate Studio) are similar—not exactly the same, but close—while the results from Honeybee-Radiance are completely different.
The room analyzed is very simple: a cube of 5x5x3 meters. I’ve set the materials as they are in Climate Studio. The settings should be the same, unless I’ve missed something, which might be causing the issue. I’ve also set the Radiance parameters with the ambient bounces. I can’t figure out what the problem is.
Can anyone help me understand why there is such a discrepancy between the results of Honeybee-Radiance and Climate Studio?
Hi @carlotta, without providing the numerical values of the study and the sample files it won’t be possible to help. Discrepancy between Radiance runs is expected and you can find several topics on that if you search the forum.
Hi Mostapha,
Thank you for your response. Unfortunately, as a new user, I don’t have the possibility to attach the script and more than one photo.
The lux values obtained for the same box are 903 mean lux from HB-Radiance, while they are 1,735 mean lux from Climate Studio in Rhino.
I know that without attaching the script it might be difficult to help, but I was hoping you could give me some tips on what to check.
I suspect the issue might be related to the Radiance parameters.
I tried to set them the same way as in Climate Studio, but the only common parameters are ambient bounces, set at 8 (-ab 8), and the limit weight set at 0.05 (lw 0.05).
For other values, the Climate Studio website mentions this: “Note to experienced Radiance users: ClimateStudio uses Radiance in a cacheless stochastic path tracing mode, which obviates parameters related to sampling density (-ad, -d, -s*) or irradiance caching (-aa, -as, -ar). To control simulation quality, simply adjust the total number of samples.*”
I thought maybe you could help me in this way. I have uploaded the gh script to this wetransfer link. I would be very grateful if you could download it and have a look at it.
Any advice you could offer would be greatly appreciated.
@carlotta I didn’t open your gh file but based on your visualization, it seems (somewhat) apparent that there is very little by the way of diffuse radiation in your room. The only light is from the direct sun. Try setting ad as around 10000 and lw as 0.0001 while keeping -ab as 8. Does that make a difference?
Hello Mostapha, since I’m still struggling with this issue, would it be difficult for you to suggest those topics/articles you were talking about?
Maybe I can find an answer to my dilemmas.
Hi Sarith, thank for you help and sorry for the late response.
Unfortunately, nothing has changed even after setting the values of as, lw, and ab as you suggested. Instead, I believe the low diffuse light you’re referring to is because it’s a point-in-time illuminance analysis set for September 21st at 12 PM. The annual daylight analysis provides much more light inside the room.
I’m starting to think that different tools really do cause these discrepancies, but it seems very strange to have such a significant difference. I don’t know which software to trust anymore.
The sensors in your grid are facing down. You can check this by the vectors output of the component. You have to flip the floor surface.
But in your case, since you have a room-based model and the grid is based on the floor surface anyway, there is no good reason to not use HB Sensor Grid from Rooms. This component will make sure that the sensors are always facing up.
The way you are adding the apertures to the model will actually add them twice. You are using HB Aperture by Ratio to create the apertures so if you want to change the modifier you should use HB Subface Modifier Subset. In the visualization below you can see that the modifier is changed for the aperture created by HB Aperture by Ratio.
