Floor plan window planning for 2 full floors flat roof 135 sqm

A few questions come to mind when I see this: After months of consideration, is this the result that has already been finalized? If I understand correctly, you now notice that the exterior views are somewhat odd and hope that someone will transform this failed Hundertwasser house into a Bauhaus? The fact that the serpentine passage between the front door and the living room is only 1m wide bothers you less? All this time you didn’t manage to draw the house including outbuildings and parking spaces on the property? Does the recess in the east façade have any purpose other than costing money and space? Do you park the car right in front of the front door so that no one can get in or out? Is an 8 sqm kitchen really the fulfillment of your dreams? On the ground floor you have a shower, but contrary to your statement, no walk-in shower without a door. Are you aware of this? Why does the storage room on the upper floor have to be windowless? The wall that protrudes into the living room and divides it — does it serve any purpose other than blocking the light? And ultimately, isn’t the orientation of the house the wrong way around for a maximum large garden? North orientation is always difficult, admittedly. But whether the windows alone can save the big luck here, I have my doubts.

Price estimate according to architect/planner: €320,000

hm… you are building 160 sqm… when was the price estimate made?
For €320,000 you currently get a 110 sqm bungalow upgraded to standard from Town & Country, if one could read that here in the parallel thread.
€3000/sqm… or even more these days.

Regarding the design: with one bathroom upstairs and then a trapped utility room, familial discord arises: you disturb each other too much.
14 sqm for a hallway compared to 8 sqm for the kitchen? The latter is hardly what suits a 160 sqm house.

open or closed architecture: open
conservative or modern construction method: modern
open kitchen, cooking island: yes, possibly island or U-shape

I don’t see that. Many confuse "open" with "all-purpose room." Open means some rooms flow into each other. But never mind, apparently the all-purpose room is intended.
However, I don’t see a modern kitchen at all.

Instead, the living room is overblown. If everything were properly furnished, you would also see the problem areas.
Many guests must pass through the hallway and entrance area to get to the bathroom.
I would put the bathroom towards the guest area, shorten the living room, give the kitchen more space by shifting the utility room. Upstairs, swap bedroom with bathroom… If the residential street is quiet, then I would start planning floor-to-ceiling windows facing south.

hm… you’re building 160 sqm… when was a price estimate made?
For €320,000 you currently get a 110 sqm bungalow from Town & Country upgraded to standard, as could be read here in the parallel thread.
€3000/sqm … and rather more at the moment.

Regarding the draft: with one bathroom upstairs and then an enclosed utility room, family unrest arises: you disturb each other too much.
14 sqm as a hallway compared to 8 sqm kitchen? The latter is not really what fits a 160 house.

We are building 135 sqm. We have the fixed price secured. Maybe now it becomes clear why I can’t do a redesign anymore. It simply becomes too expensive, because then it is recalculated daily.

There are three of us. Simultaneous use of the bathroom will be limited and there is also a shower toilet on the ground floor.

I don’t see an island. Many confuse “open” with “all-room.” Open means some rooms flow into each other. But whatever, apparently the all-room is wanted.
However, I don’t see a modern kitchen at all.

The kitchen will be small, yes. In our current apartment it isn’t much bigger and still has a dining table instead of a half-island.

But then the living room is too inflated. If you’d properly furnish everything, you would also see the problem areas.
Many guests have to go through the hallway and entrance area to get to the bathroom.
I would make the bathroom accessible to guests, shorten the living room, give the kitchen more space by shifting the utility room. Swap bedroom and bathroom upstairs… If the residential street is quiet, then I would start planning floor-to-ceiling windows facing south.

Unfortunately, I cannot follow how all these changes would look here.

The windows upstairs facing south in the child’s room and bathroom are already floor-to-ceiling. On the ground floor floor-to-ceiling doesn’t make sense.

And, sketch in some furniture, especially the kitchen. The area is not that huge, and you really have to plan carefully. I don't see an island there at first. A U-shape particularly restricts cooking with more than one person.

If everything were properly furnished, you would also see the problematic areas.

What we both want to say is, you are presenting a floor plan without scale-accurate drawn furniture. It is obviously not clear to you where the narrow spots of the floor plan are. Therefore, you should invest time and do that once, for example, paths from kitchen to terrace or guest bed in the home office would then become clear. Especially to finally tick off your wish list

open, kitchen island: yes, possibly island or U-shape

Office: family use or home office?: home office/guest room

Also drawing the house with carport/garage/car parking space can be helpful to identify narrow spots at the entrance, for example.

I would try choosing different window formats on the upper floor. More horizontal formats instead of floor-to-ceiling and narrow ones. These only reinforce the impression that building elements such as [e.g. balconies] are missing and dissolve the floor division too much.

The windows on the upper floor facing south from the child's room and bathroom are already floor-to-ceiling.

On the upper floor, it makes little sense to allow views below the belt.

Floor-to-ceiling windows on the ground floor don't make sense.

At least in winter, some daylight still comes in on the ground floor. Otherwise, I'd say: with the current planning, it's a dark cave for at least half a year.

Unfortunately, I can't follow how all these changes would look here.

I don't understand how you can't comprehend it: toilet at the back left (plan), let everything else rotate counterclockwise.
If you furnished it yourself, you'd understand the point behind it.
Currently, there's probably not much more that can be done for you, since you resist criticism even though you asked for it.
Upstairs, there are more sill-level windows; downstairs, you need them where the sun shines during the day in winter. Then comes the room planning!