OpenStudio has caught a self-intersecting polygon face (or polygon) here (see line 950). . Maybe post the whole error output (which output, which I believe should list the culprit polygon problem face vertices in sequence ... like sequence (like this). Better yet, provide a link Should be easy to the generated .osm file. The issue is likely due to the sequence of vertices of some surfaces (e.g. "Face 245", "Surface 35"), or those of their adjacent surfaces.diagnose.