How to chose Brep face by normal?

I am performing solar exposure analysis on many buildings in a city neighborhood. I really only need the results on the south facades of the buildings. It makes sense to me that i should be able to perform DeBrep on the buildings, and choose all south facades as surfaces for radiation analysis, but i cant figure it out. Does anyone know how to do this?
Thanks alot


What I did is to bake the surface brep and go to rhino to check the normal face direction (click the baked surface to show the direction you will see the U and V direction to see which direction it is facing horizontally and vertically). And make sure it is facing the direction as supposed to be. So the south facing facades should be facing the south direction as desired. Otherwise it may face other directions, sometimes after I make some modifications with the geometry the facing direction may get changed. It worth to check each time before running simulation or after you make changes for the geometry.

If you have the Legacy installed you can look for the separate By Normal component in the Extra group.

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Maybe you can get the result by filtering vectors,I do a demo ,but I am not sure if it is your need,maybe you can add more filtering condition.Hope can help you


Xiao thank you SO MUCH! it was choosing all the north facades, until i understood that the * expression by the Y axis had to be -1. This is exactly what i needed! you are amazing!

didn’t find that component- i must not have legacy. i will look for it thanks!

Thanks but i need a solution that can work for many buildings at once, so baking and checking visually in rhino is less ideal for me