First draft from the architect - optimization

A terrace is basically a simple flat roof and its watertightness is initially independent of its use. You do not damage the waterproofing with the terrace slabs. Think of terrace houses.

No specific division by basement/ground floor

Unfortunately, that is exactly how it looks to me as well, i.e., my main criticism here would be the mass distribution following the motto "the non-intersection of the floor areas is left to chance," here with the consequence of an unnecessarily bulky terrace. I would prefer more lawn at the garden level. A north arrow on the floor plans would also be nice.

Hello everyone,
first of all, many thanks for the quick and numerous responses. I will try to reply in a structured way.
I can consider the topic of the terrace’s waterproofing as settled.

I also find the size of the terrace too big. 11ant described it quite well. But in our opinion, the rooms in the basement are not that big (except for the hallway). We have considered whether to extend the living room a bit more towards the terrace, so that there is only a smaller "path" to the garden. And then put the bedroom on the ground floor. But then the WC would also need to be enlarged... Or would that make everything too cramped?
The basement would then be reduced in size. What do you think about this? Also regarding children who would then have their rooms "alone" downstairs. In the beginning, the office could still be used as a children’s room...

Regarding the hallway, besides the size, I also see light as a problem. That’s why we like that the hallway ends with a window/door for daylight. We are trying to tweak the room allocation to still have daylight in the hallway, but not make it so big, e.g. to shape the hallway as a Z.

I always see the direct access to the garage, but I don’t think I would do it, especially because of smell, dust etc., and the main entrance is right next to it.

Good point. But a direct way to the garage would be nice; otherwise, you always have to go through the garage door. Maybe the door to the garage shouldn’t be too close to the entrance/stairs...?

Why not live downstairs with direct south and west garden access?
Has the statics been calculated already?

Because of the view, we want to live upstairs. Garden access is possible via the terrace and to the north side. I don’t think the architect has calculated the statics yet. He just says that not many retaining walls are needed. (Picture northwest view)

About the costs: We told the architect roughly 400K€–450K€, so that with additional building costs + kitchen + land we stay within a maximum of 550K€. The land cost 50K€. Therefore, we would like to reduce the living area a bit and also the terrace. And switch to a shed roof. That should be possible, right? How much could one roughly save by doing that? But of course, regarding the building costs, we primarily have to talk to the general contractor...

Many thanks again for the support.

PS: I have re-uploaded both floor plans with a north arrow (can you no longer edit your post?). Should be approximately correct.

Yes, editing is limited to 10 minutes.

But the rooms in the basement are in our opinion not that big (except for the hallway).

If the sizes of the individual rooms fit - and I assumed that - then a redistribution of the building volumes practically means: booking rooms to a different floor.

But a direct way to the garage would be good, otherwise you always have to go through the garage door. Maybe the door to the garage shouldn't be placed so close to the entrance/stairs...?

That sounds contradictory to me. In general, when in doubt, I am "pro no intermediate door."

I find the draft successful. The long hallway has character. You can shorten it by enlarging the last room and placing the entrance at the end. With a window or even a "side entrance" it is of course much nicer. ... I would also be reluctant to put it in the pantry due to the heat generation.

I also think that the long hallway can have its own character and does not remind one of a hotel corridor. Rather rare, but definitely not off the rack. But seriously now - how much heat generation does a modern refrigerator / freezer really produce that it noticeably warms the pantry unnecessarily? Please don't talk about a 0.2 - 0.3 °C temperature increase in the room.

But seriously - what kind of heat generation does a modern fridge/freezer really produce that it noticeably and unnecessarily warms the pantry? Please don't talk about a 0.2 - 0.3 °C temperature increase in the room.

The heat exchanger principle is still the same with the "modern" fridge and freezer. That doesn't matter for today's so-called "pantry," which is a storage place for pasta bags, dust bags, and deposit bottles. And for a classic pantry, a north-facing orientation would be recommended anyway.

Yes, the heat from the refrigerator / freezer is vented outside. Can you say how many watts are actually released into the ambient / room air?

I can only speak from my current room, where there is a large fridge/freezer combo, and I don't notice it either in summer or winter. That's why I thought it might be negligible? It could also be that I am wrong?