Floor plan single-family house 240m² on a gentle slope

Congratulations. Your architect has put some good thought into the renovation. I really like that.

I think it’s quite nice to consider keeping part of the old structure. But that sets many constraints that I wouldn’t want to adhere to with this budget. A plus point for sustainability?

I think the glass wall to the open space is a good idea.

The staircase is not my thing. At this price range, I would want at least a landing staircase and large windows. (Without windows, that’s impossible).

Bathroom in the studio without a door to the bedroom? At least a frosted glass door.

The water pipe from the bathroom in the studio is supposed to go right through the living room to downstairs?

The apartment bathroom should have at least a full-width clerestory window at a 2m sill height outside, then a light well.
The basement apartment should become a man cave, media room, or library depending on leisure activities?

I also don’t like the children’s room directly next to the living room.

The guest toilet could also have a clerestory window. Whether it bothers someone if someone turns the light on there then remains to be clarified.

The mentioned options for the children are well-meaning theories but not well thought out.

Currently, a small child is moving into the attic in the office/guest room.

The child has too long a way to the toilet, only through the parents' bedroom and then without a door?! …

We could offer 2 teenagers their own areas within the house.

And the access to the child goes through the dark utility room-basement…
The family unit is torn apart: especially teenagers should not live uncontrolled, but live communally within the family. That all seems too fragmented and too pragmatically thought out to me.
Instead, the two 12 sqm children's rooms next to the large and spacious living/dining area again seem like a punishment.
The rest regarding windows and drainage of the upper floor bathroom and the emergency stairs has been well summarized by .

About airiness: The dining area has no, absolutely no quiet wall anywhere where something can be placed or hung. The occupant or viewer will not be able to grasp a quiet wall or zone. There are extended areas everywhere. Additionally, the ceiling is opened up. You can also see across to the pantry from the sofa. Don’t forget that airiness and spaciousness as well as spatial effect also have something to do with furniture or the design of walls.

Congratulations. Your architect has put some good thought into the conversion. I like that a lot.

Thank you

At first, I think it's quite nice to consider preserving parts of the old building. But that sets many constraints that I wouldn’t want to adhere to with this budget. A plus for sustainability, though?

The staircase is not my taste. At this price range, I would want at least a landing staircase and large windows. (Without windows, that’s impossible).

The existing staircase is not my taste either and will be newly built, but in the same place. That was a result of the last discussion. There is a window in the existing building... we are quite close to the neighbor. Impossible because it would be too dark in the sense of "basement-like"? Where do you see further constraints?

Bathroom in the studio without a door to the bedroom? At least an opaque glass door.

Right, I see it the same way.

Water pipe from the studio bathroom is supposed to run right through the living room downwards?

No idea. So far I assumed that one can manage this technically and acoustically quite well. Is that a wrong assumption?

Bathroom of the apartment should have at least a full-width strip of daylight at parapet height of 2m outside and then a light well. The apartment in the basement should become a man cave, media room, or library depending on recreation preferences?

We originally thought of the basement room as utility space. Then came the additional "basement entrance" from the garden, then the sunken courtyard, then the bathroom. To eventually be able to use it as an apartment for a child in X years. The apartment will initially be a fitness/hobby room.
I am not a fan of these light wells; you pay for the light downstairs with "visual unrest" above or "holes" in the garden/terrace. I spend most of my time upstairs; I am only briefly in the bathroom. But we will think about it again.

The guest WC could also have a strip of daylight. Whether it bothers someone if someone has the light on there is to be clarified.

The daylight strip would be, for example, towards the cloakroom/stairs. I think that wouldn’t bother anyone and would provide some light?

Thank you very much for your input; I found it very helpful.

The options mentioned for the children are well-meaning theories, but not well thought out.

The child has too long a way to the toilet, only through the parents' bedroom and then without a door?! …

Currently this is a child in diapers, but there is something to that. A door needs to be put in, I agree. Maybe someone has a good idea for the way to the toilet?

And access to the child goes through the dark utility-room basement… The family bond is torn apart: especially teenagers should not live uncontrolled, but rather live together within the family. To me, all of that seems too fragmented and thought of too pragmatically.

The children's area is a dilemma for me. The sweet little ones should be as close to the parents as possible and sleep peacefully. Sure. Then they get older, have friends staying overnight, and later are pubescent teenagers with all that entails. The classic upper floor with bedroom and children’s rooms, in my view, comes with many other disadvantages. As parents, I can better take the negative accompanying aspects of a solution into account in the interest of the children. If I remember my own youth, avoiding disturbing my parents at night was not a priority. I think of loud computer games, music, ...

Our consideration on this: We are not the loud home-cinema type and generally not big TV people; we only want one TV in the living room so that the family can occasionally watch something together there. Possibly we wanted to place another TV upstairs in the small lounge area.

But I have already assumed that the wall and door that divide the corridor of the children’s area can be technically done so that the living room can be used without noise in the children’s rooms. Is that wrong?

Instead, the two 12-square-meter children’s rooms next to the large and spacious living room/common area again feel like a punishment.

Can you explain that in more detail? – I would like to understand that thought well.

Can you explain that in more detail? - I would like to understand the idea well.

75m² of open space and 42m² of parents' area stand in stark contrast to 12m² children's rooms. To put it bluntly, one could also say, only the best for you, minimal size rooms for the kids.