I do agree about the aluminium part: I say metal in a more general sense of the word - alum, or iron, or steel, or some composite metalic material. So, yes aluminium seems right. Those fins are most likely a solid “metal” of some sort…
All the other facade panels are sheet metal, that is a given - it is those sold ‘fins’ that make this facade look so substantial.
I am willing to bet those fins that protrude out around the windows are ‘solid’ - whatever the material. I think they are probably solid because they are just too thin (less than 1" ) to be hollow.
I think you are often right; but on this one I will need some evidence… 
I would be interested to know for sure… I think we can actually find out for certain and post on this thread: it will be interesting to know for those who are interested in these types of details. I will check around a bit (but not too, much) and post if I can find any ‘solid’ info - pun intended - on the matter.
met·al | ˈmed(ə)l |
noun
1 a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity (e.g., iron, gold, silver, copper, and aluminum, and alloys such as brass and steel): being a metal, aluminum readily conducts heat | vessels made of ceramics or metal.