Giant digital fabrication CNC

Machine time for something this big is very expensive: that's why it's used for making molds, which is a fabrication technology that scales up very easily; unlike CNC machining, which doesn't scale at all.

Additionally, surface finish with ±0.2mm X/Y is going to be pretty poor. It won't produce finished parts, you'll need to sand/grind it, or coat it with fiberglass and sand that. It also doesn't mention deflection under load, or feedrate through anything tougher than foam plastic.

There's a big 3D printer that is very suitable for architectural projects. Check it out:

http://d-shape.com/

CNC is probably less useful for printing houses, it's great for negative molds, but harder when you have overlapping empty spaces. It's more useful to have a 3d printer here -- maybe someday we'll have 3d printers that use concrete foam to create simple prefab homes.