What ceiling height have you chosen?

And what parapet height do you have then?

1.265m on the ground floor and 1.185m on the upper floor above finished floor level. These are the wide windows you also see in my profile picture. We also have 4 narrower windows (dressing room, utility room, second window in the bathroom, and in the guest WC) each with a parapet height of 1m above finished floor level and a height of 1.20m. In any case, everything has been planned so that the top edge of all windows is at the same height.

I have a question for everyone who has built with a ceiling height of 260cm. Specifically regarding the window sizes.

If we set the windows at 90cm sill height and I allow 30cm for the roller shutter box, I have an opening of 140cm. Did you use this fully or how did you proceed here?

Throughout the entire house (except for the kitchen window, guest WC, and a decorative window) we have exclusively floor-to-ceiling windows, even in the attic (roof windows with attached knee wall windows). The "decorative window" in the living room next to the couch has a sill height of 40cm – my wife at least wanted a window where you can put things on the windowsill.
Overall, this naturally resulted in extremely bright rooms.

1.265m on the ground floor and 1.185m on the upper floor above the finished floor level. These are the wide windows that you also see in my profile picture. We also have 4 narrower windows (dressing room, utility room, 2nd window in the bathroom, and in the guest WC) each with a parapet height of 1m above the finished floor level and a height of 1.20m. In any case, everything was planned so that the top edge of all windows is at the same height.

Then your wall looks as follows:
Parapet height: 1.265
Window height: 0.80
Roller shutter box: 0.30
Lintel: 0.235
Or do I have a flaw in my reasoning here?

Throughout the entire house (except for the kitchen window, guest WC, and a decorative window) we have exclusively floor-to-ceiling windows, also in the attic (roof windows with attached knee wall windows). The "decorative window" in the living room next to the couch has a parapet height of 40cm – my wife at least wanted to have a window where you can place things on the windowsill. Overall, this has resulted in extremely bright rooms.

We had thought about it for a long time as well. But now we are at the point that we don't want that. Question: how wide are your floor-to-ceiling windows, especially on the upper floor?

Then your wall looks as follows: Parapet height: 1.265 Window height: 0.80 Roller shutter box: ,30 Lintel: 0.235

I have neither recalculated nor remeasured. But that roughly fits.

Question, how wide are then your floor-to-ceiling windows especially on the upper floor?

They are 1.50m (two sashes) or 1.0m (one sash), whereby we only installed the small windows twice.

Maybe as an addition: The structure you mentioned above is, for example, the bay window at the bottom of my profile. We used this room as an office. The high parapet has the advantage that from the outside you cannot directly see whether someone is sitting at the desk or not. It looks similar at the two right windows upstairs. That is the hallway and bathroom; I also find it quite pleasant there. In the children's room at the top left, a smaller child naturally cannot see anything out of the window. But the room also has a floor-to-ceiling window a little further back.