Thanks. Hoping this will change soon though or that at least we'll be able to enter our own BDSFs...also blocking all direct sun is a function of lat, long and orientation so it's hard to imagine, apart from being fully closed, that there could be a single slat angle that could do it for all lat, long and orientation.

I don't expect this will change anytime soon, as there is no funding to work on this. At least from the application side. As for the slats, I should have said "most of the year, on the south, mid-latitudes". =)

Thanks for clarifying..and for orig answer. Reminder to self, don't mis-spell BSDF like I did above and search on internet.

Since it's "Open"Studio, I'm hoping to track down how I can edit the code for some work-around to use my own BSDFs. So far it looks like the key file is blinds.xml (for blinds). Everything else seems either the same or is generated from blinds.xml. The problem I see though is that blinds.xml is generated anew each time. Am I on the right track?

...rob, in my digging saw what rpg stands for. This is Eric Shadd, former energy modeler at AEC San Francisco.

Yep @Determinant (Eric! Hi!!), the whole Radiance model including the BSDF file system is created each time the Radiance measure is run. It actually happens when the model is translated from OpenStudio to Radiance format. You'd need to write a little script (measure) to add your own custom BSDFs. Ideally, we would add some option to the Radiance measure so you could specify alternate BSDFs, and that will be easy to do when version 2.0 of PAT is released later this year. Meanwhile you'd need to make your own version of the Radiance measure.