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

Single-leaf? Double-leaf? What widths and heights? Double-leaf with or without a mullion? What are the advantages and disadvantages of these windows?

First, I would (ideally, the architect does this, but often one builds without one) determine the lighting requirements for the individual rooms. Depending on the room size, this results in (minimum) window areas, which can then be expanded as desired. Children's rooms should be brighter, whereas for the guest WC it is somehow not so important. ... Particularly nice, in my opinion, are corner windows or rooms with windows on two adjacent walls. This process always has to be coordinated with the views of the house (which are more or less determined by the floor plan).

Whether single- or double-leaf mainly depends on the width of the window. Very wide windows lead to heavy sashes that also protrude far into the room when the window is open. Logically, you have many double-leaf windows (because in the first step large window areas for lots of light were determined).

Whether with or without a mullion (without means a Stulp window) is a matter of taste. Without a post, the possible clear opening is larger; however, the second sash cannot be tilted and can only be opened if the first is opened (so you have to decide which sash should be the first; tilt-turn). In Stulp windows the central bar is narrower (more light), but some may perceive this as asymmetrical.

Floor-to-ceiling elements are certainly fashionable and provide a lot of light, but in my opinion they severely restrict possible furnishing. Unless you like the rear view of typical desks (with all the Wi-Fi cables and power strips).

One more thing: large windows are more expensive than small windows. Windows are more expensive than normal walls.

We chose all double-leaf windows as Stulp windows. Upstairs we have no floor-to-ceiling elements.

The 40 cm parapet height from could also appeal to me. If it fits the overall concept, this is especially great in the children's room (playing little ones can still look out), in the bedroom (lying down seeing the beautiful garden), or in the bathroom (lying in the tub seeing the beautiful garden). For various reasons we gave up on this, but we also build rather standard and not an architect-designed house.

could we see some pictures of that?

I can gladly do and post it on Friday.

We are very pleased about the 40 cm parapet heights on the upper floor – airier than normal parapet heights, but more private than floor-to-ceiling (sounds silly, but hard to describe)

A parapet height of 40 cm on the upper floor is not allowed without additional fall protection. 40-50 cm parapet height is meant for sitting, 80-90 cm for standing in front of it. A minimum of 80 cm is required by regulation. This can be found within 2 minutes using Google.

If you don’t want a parapet, basically the only option is our method with the glass panel. However, hardly anyone uses it; most go with the parapet.

The windows have fixed parts...

the lower part is fixed with a height of 80-90cm? so like with us? (Bilder Seite 1 post 2-3) then the parapet is superfluous.