I don’t find your idea wrong, but I’m afraid it will be difficult to implement due to the following points:
-Max 15 m boundary construction (of which max. 9 m per side) allowed, with the planned dimensions I would be at 17.73 m total length, although you might still be able to plan it down so that you reach the max. 15 m, but then at the expense of the size
-When building directly on the boundary, may I completely detach from the building footprint? I don’t know if your proposal fits the building footprint (see attached sketch)
-The floor area ratio is nearly exhausted with the originally planned design, here an additional half double garage (almost 40 m2) would be added, plus the courtyard in front would probably have to be designed somewhat larger because of the slope situation, for that the long path to the front door on the north side would be omitted... that would have to be calculated/planned
Once more briefly about the spacious wellness/fitness area: I have been doing sports for min. 7-8 years at least 3-4 times a week for at least 1 hour per session (cross trainer, dumbbells, cycling...). So in principle, the room would be used intensively and not just as the next step towards the desired activity.
The wish here is that it is designed so that it is a bit more pleasant/spacious.
Regarding the way to the car: The “I forgot something in the car and have to run back” is negligible or does not apply here.
And what a terrace facing south/west means is well known. My parents’ house is about 800 m on the same mountain with an identical terrace situation. Therefore, I know very well how and when the sun stands and what that means for the usage behavior of the terrace.
