Evaluation floor plan approx. 145 sqm single-family house basement/ground floor/upper floor

I think you should remove the entire basement floor from the thermal envelope. That means: a partition wall/door to the staircase in the basement.
The office can be heated electrically.

What exact advantages does removing the basement floor from the thermal envelope have? Sorry if this sounds stupid. Savings on energy costs? But it simultaneously increases construction costs, right?

That’s nonsense. Removing the basement from the thermal envelope is nonsense if the office remains inside. That is a living space and would then need to be individually enclosed in a thermal envelope. I won’t even comment on the electric radiator.

Basement floor outside the thermal envelope has exactly what advantages?

That it can be built cheaper :)

We already had a recess for the wardrobe in the design, unfortunately it doesn’t work for us and makes the living room too cramped :-(

And where is it planned now? There isn’t much space in the middle of the hallway… how do you imagine that with two children? Leaving it out doesn’t help!

The storage room could also be used as a wardrobe. If you have a basement.

The storage room could also be used as a wardrobe. If you have a basement.

I wrote that. #29. But it would be interesting to know how the OP envisions it.

The terrace next to the house towards the neighbor in a SE direction is ultimately on that side because the sun shines there in the morning and at noon. A terrace facing north, i.e. on the other side of the house, would be better in terms of view and privacy, but you never have the sun there.

Attached is the view from the upper edge of the property (east) heading west.

The view is great and I would definitely mirror the house! On a north-facing terrace you do have sun, namely in the morning from the east and in the evening from the west. Only during the midday heat would you need to build a second terrace to be able to grill there. On the southeast terrace you are not only sitting right next to your only neighbor but also in the shade in the evening ;)

That it can be built more cheaply

As a utility cellar, yes - but that is not how we have it here.