That's not true at all. Individual or terraced houses are not "common property" and owners are free to install what they want. Apartments buildings with multip

That's not true at all. Individual or terraced houses are not "common property" and owners are free to install what they want. Apartments buildings with multiple owners are governed by a "syndic" that is comparable to American HOAs (as far as I understand HOAs) and they can put restrictions on AC installations if a majority of owners agree. Usually the most annoying part is that you need to wait a couple of weeks for permission to drill through the exterior wall (which is common property obviously).