Light pipes and phase methods

Hi community (@sarith and @mostapha).

Does anybody know how to do annual daylight simulations from a light pipe using 3 og 5 phased method in HB[+]??
Is it at all possible to do in Honeybee?
I am using a windows computer and therefore I don’t think I would be able to do this using “raw” Radiance.

Christian Bech

@sarith did share an example but it is not really using the Grasshopper interface. He used the core libraries to do that. For modeling a light-pipe you need face to face coefficient calculation which we haven’t exposed it in the interface. Andy’s presentation in London is still the best reference that walks you through each step.

The only step that will be challenging on Windows will be using genBSDF so if you already have bsdf files to define the up and bottom of the pipeline you should be able to use Radiance from the command line with now issues.

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Hi @mostapha and @C.Bech

That was so 2014 :wink: ! Actually the Four-Phase method is the way to go.
There is some amount of “magic” in Andy’s solution as it requires you to switch between probabilistic and deterministic sampling in the same workflow:

To be fair, his solution was far ahead of it’s time because this was long before the Four-Phase Method was “invented”. After understanding the Four-Phase Method, I had tried something a couple of years ago just to see if it could be made to work(The images in the bottom row are from the four-phase simulation):

Anyway, during last years workshop Taoning presented a short validation of the Four-Phase Method with regards to light-pipes.

The “facade” in the context of the Facade matrix is the light pipe. Depending on how comfortable you are with commandline Radiance, the simplest approach would be the F1 type Four-Phase Method ( , page 58). And you should be able to make it work on windows. At least computationally this method is not very intensive.
If you face any issues in setting up the simulation through commandline, let me know.


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Thanks a lot @sarith and @mostapha.
I will try to give it a go and see if I can manage to do it with the Four-Phase Method.