Question-and-Answer Resource for the Building Energy Modeling Community
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I interpret this as a condition for truncating which goes for both the vertices of the input geometry in Shading:site:detailed as well as the vertices of the shadows which are projected from these surfaces. (not sure)
Using this modelling approach you will only get shadowing and a single reflection (so no inter-reflections between blinds). Also the accuracy really depends on your settings for the solar distribution and the polygon clipping algorithm which processes overlaps between shadows.
I would make sure set the Solar Distribution field withing the Building object to 'FullInteriorAndExteriorWithReflections' and also experiment with the 'Maximum Figures in Shadow Overlap Calculations' and the 'Calculation Frequency' fields withing the ShadowCalculation object.
Even then I would still have some doubts about using this modelling approach as I don't the exterior shading algorithms where developed with things like blinds in mind. A good way to test it would be to first consider a very simple case (straight blinds, at a particular angle) and model this using both the method/settings you have in mind as well as using WindowMaterial:Blind approach.
