I see your point; but we are both making only conjecture about those ‘fins’. I believe they are solid metal that is about 1" in thickness. This is a simple question that we can get a definitive answer from someone who knows for sure. It would be nice if the builder or architect could chime in on this quesiton.
I think the best way to find out is to see the manufacturers shop drawings with detailed sections and written specifications. I think it would be a good academic exercise to find out for certain: so I will do a bit of checking around and get back to this thread with whatever I find.
The continued posting here may stir up someone who is a subject matter expert, or working directly on the project: that would be great.
Here is an example of proof positive that a window mullion or louver is made of hollow sheet metal. I am hoping to find some similar evidence showing the needed details. This is from the building in Brooklyn called Alloy Block…