Types of windows: single-leaf, double-leaf, which widths - experiences?

I like floor-to-ceiling windows with a fixed lower window. However, I decided against them because, as you write, cleaning these windows is somewhat complicated.

What are the dimensions of your windows?

The windows have an installation width of 1.75m at the top and bottom each, according to the execution drawing.

Cleaning the windows is indeed a bit more complicated, but you don't risk breaking anything. We have a sprayer and squeegee device from Kärcher. Spray once, wait 2 minutes, then pull off with the device. Done.

Floor-to-ceiling windows upstairs let in a lot of light and look good. The advantage of the closed lower part is that you can let small children play here, including with a view to the outside. (Including tilting or fully opening). Of course, floor-to-ceiling patio doors upstairs mean a railing, but that is by far not as nice (and also more expensive). In the end, everyone has to decide for themselves. As you can see yourself, floor-to-ceiling windows are visually really great and look even better from the inside (nice and bright).

PS: Another disadvantage shared: if you want to install pleated blinds, our element is really expensive because the width of the pleated blind determines the price (with us, just one pleated blind costs about €250). But you almost inevitably need it because anyone can look through the room from outside. You don't have the shutters down all the time...

We have on the ground floor
2 x floor-to-ceiling 1.86 m (bedroom, living room)
1 x floor-to-ceiling 4 m (2m+2m fixed) (living room)
2 x floor-to-ceiling 1 m (living room, utility room)
1 x 3m lift-and-slide door (dining area)
1 x 94 cm railing 1.86 m with fixed parts for sink (kitchen)
1 x 94 cm railing 1 m (kitchen)
1 x 100 cm railing (?) 0.75 m (WC)
1 x front door with side panel 1.86 (hallway)
1 x 94 cm railing (?) 88.5 (parents’ bathroom)

We have on the upper floor
4 x 40 cm railing 1.86 m with fixed parts at the bottom (children’s room, office, guest room)
2 x skylights (bathroom, utility room upper floor)
2 x railing (?) 0.75 in cold roof

All 1.86 m widths are double-leaf.

We are very pleased about the 40 cm railing heights on the upper floor – airier than normal railing heights, but more private than floor-to-ceiling (sounds odd, but hard to describe).
The 4 m in the living room makes the room very bright. The 3 m lift-and-slide door is very practical, as it can be kept open without getting in the way (no idea if this will actually be used in practice later) – these are my impressions.

Window with a 40 cm sill height is interesting. That definitely looks very stylish. Worth considering.

How high is the fixed part of these windows then? 50 cm? So that the total reaches the required 90 cm? Or are the regulations different there? Because children could theoretically climb onto the windowsill and fall out of the window more easily. Or am I seeing that wrong?

Interesting consideration - no, the fixed part is about 50 cm; but it seems okay; the windowsill is also not that wide. Whether it is chic probably lies in the eye of the beholder

ps: another shared disadvantage: if you want to use pleated blinds, our unit is really expensive because the width of the pleated blind determines the price (for us, just one pleated blind costs about €250). but you almost inevitably need it because anyone can look into the room from outside.

Therefore, I often advocate for windows with a 90 cm sill height. This also increases the placement options for desks, dressers, beds, etc. I don’t find it very nice when, in front of floor-to-ceiling windows, lots of furniture elements or cable clutter from the desk become visible.

We were told that windows from 1.20 m with only one sash (due to triple glazing) are too heavy. Therefore, we have chosen all windows and doors from 1.20 m with 2 sashes without a mullion.