Floor plan and elevations for a single-family house of approximately 160 m² on a hillside location

The floor plan in this form is not wrong in itself. I would personally just not build it that way if the house is planned as a forever home and not as a family house to be used for 15-20 years. The idea of having to fill so many rooms with life as a couple would not be for me. I would rather plan it so that it is a bit tighter with three children for a few years and later appears verschwenderischer pardon, more spacious. But that's just me.

East next to the house, I would only minimally adjust the terrain.

What nonsense are you talking about? East next to the house you have planned a galactic light well. Nothing about "minimally adjusting."

From the rear edge of the house, for example, one could aim for an average terrain height of 463.60. The terrace and the ground floor might then be around 464.80. As said, all just initial thoughts at the moment. Maybe both 20 cm higher as well.

So you want to remove half a meter behind the house and then put the terrace on stilts? Will mice live underneath, or will you fill it up again and build a platform into the landscape so the neighbors can see and hear you better? From the platform, it then goes down next door to the next light shaft.
Good grief, what a mess. And then the clients complain they were poorly advised, like here:
https://www.hausbau-forum.de/threads/haus-ragt-in-hoehe-wie-hoch-erde-aufschuetten-kellertiefe-gering.44345/

Unfortunately, the pictures are gone, probably the OP was too embarrassed.

To the other comments like water disposal, chimney in the upper floor, and space waste or shortage, there is stubborn silence. Only the kitchen is talked up as sufficiently nice.

So far I only see nonsense and hope you come to your senses. 700K for a house and your kitchen is smaller than in my former 2-room apartment. Wake up! Throw this away and go to a real architect!

I share Hanghaus's idea as well. Namely, that you add a room at the bottom and thus save the basement, and the floor space then increases on the ground floor/upper floor. And regarding the incidental costs again. Don't forget the following items:

[*]Property transfer tax [*]Building application [*]Building permit [*]Surveying [*]Soil report [*]Possible demolition of old buildings [*]Tree felling work [*]Establishment of a construction road [*]Removal of soil or soil exchange [*]Development costs (electricity, water, sewage, telephone, etc.) [*]Construction water and construction electricity [*]Insurances

That can add up to another mid five-figure amount.

Yes, thanks again for the list. We won't need all of that and so far have calculated with 10% of the house costs. So a mid five-figure amount. That seems to fit with our assumptions. But it was basically already planned in the costs. However, as mentioned, we still need to discuss the costs with the architect and possibly get offers. Then we'll see where we actually stand.

I don’t really want to suggest changes to the floor plan because, like ypg, I have the impression that the builders love their design too much since it includes just about everything one needs today. I rather have the feeling that the floor plan will only be critically tackled once the first complete and concrete offers are available and it becomes clear that 100,000 euros are missing from the budget. I would recommend revising the house on the left side, shortening it, and giving up the ideal utility room with garage access, realigning the kitchen, and removing the third shower from the guest toilet. With a > 80 sqm basement and a big garage, I don’t need a large storage space. Personally, I would forego the basement and try to structure better above ground. If the development plan allows it, I would, if necessary, enlarge the footprint and build 110 sqm per floor.

Thank you for the constructive contribution. Yes, everything we like is included and we would also prefer a basement rather than 2 floors with 110 sqm. (This could become Plan B) According to all the previous information from companies, however, we first have to assume that we are not missing 100,000 euros. But you’re right, if we find that this actually won’t work, we will have to redesign. For now, we just wanted to optimize the current floor plan or identify its weak points from your perspective. These are, for example, kitchen too small, children’s bathroom upstairs, and the design of the plot including the terrace.

We now want to discuss these topics with the architect. Regarding the kitchen, we simply have a different opinion than you. But this is a personal assessment from us.

The floor plan in this form is not wrong per se. I would personally just not build it like this if the house is planned as a forever home and not as a family house to be used for 15-20 years. The idea of having to fill so many rooms with life as a couple would not be for me. I would rather plan it so that it’s a bit tighter with three children for a few years and later wasteful pardon, more generous. But that's just me.

Yes, thanks also for the hint. We see it the same way, but have now decided on the larger version so that it fits now, and later we will have to see what that means for us.

I’m only here for short visits now, so quick & dirty summarized: to me, this appears to be a textbook case of slave-to-the-sign planning, which especially backfires badly on slopes. With the tidal range in the construction window, I already see underground earth-contact components threatening just by averaging the heights, which reflexively leads wood-frame "prefab" house builders to pull the basement of a cooperation partner out of the drawer as a universal remedy. "What you don’t have in your head, you have to have in your legs" translates on slopes to every laziness in using the grab leads to expensive earthworks. "On the builder's side" positions keep the budget delta below the warning threshold until the start of construction. Let them optionally offer you the garage "turnkey", then begins the rose-colored water paint to run down the glasses. But thanks for the inspiration, I’m working on a "this is how the dream house goes wrong" guide in the medium term ;-)