aA are not responsible for the towers at West Block, those are by IBI Group. aA only designed the Commercial building. In regards to the material choices, sure it's the materials. Back-painted glass spandrels are typically the cheapest option for opaque walls, so they're normally paired with smaller, cheaper pieces of glass that are framed by that dense grid of mullions that make so many towers look cheap. (Powder-coated aluminum spandrels generally the second cheapest? Anyone know for sure?) Pretty much every other wall type costs more, so any developer choosing something else is doing us all an architecture favour, and earning varying degrees of gratitude from us.
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