Just one note... maybe you should also try to factor in (maybe it's impossible, but do keep this in mind when comparing the two buildings) that probably some th

Just one note... maybe you should also try to factor in (maybe it's impossible, but do keep this in mind when comparing the two buildings) that probably some things were added later to the original 13-months building, like better thermal insulation, phone cables, air conditioning while the new one have these from the start. So you should compare 13 months/$637M + X months/ Y millions to update the original building to new standards.