Casa Luca was a project borne out of a necessity for a bigger space for a growing family. The process started as such but quickly evolved into an opportunity to achieve a commonly desired housing type for the young urban family and tailored to a certain sensibility of esthetics.
Designing passive houses can be a bit of a numbers game, pushing here and pulling there to ensure that the house uses only so much energy. Windows, in particular, have to be carefully controlled and designed so that not too much heat is lost on the north side of the house. However it's good to pick up solar gain where you can on the other sides.