One feedback - for the integer values like number of storeys and bays, it would probably be better with like a "+/-" or a slider. But just my own UX opinion ;-)
This is awesome! I can tell this is a huge amount of work selecting the correct type and amount of variables.
Cool, but to add more character, you can add a feature to add colored materials maybe?
This is beautiful and as an aside, I love the clean minimalist UI as well!