Window variants: Stulp vs. mullion

Dear forum community,

I kindly ask for a brief assessment of the window options.

It concerns the windows in the children's rooms. These are the second windows, meaning there is also a floor-to-ceiling window on the gable side.
The windows in question (with blinds) are located on the eaves side (south side) in the knee wall (finished interior height 1.80 m) and are currently planned in the size 2 m x 70 cm (height x width 72 cm) (it is known that fall protection is required). The children's rooms are 15 sqm – so the lighting is more than sufficient.
In the meantime, however, we are no longer sure whether 2 meters might be too wide; we are now tending towards 1.76 m width. However, the windows are not tall, which could possibly compensate for the width.

Now the question is, do [Stulp windows] offer advantages here for better light yield, or windows with a central mullion? Load transfer through the window does not have to be ensured.

Has anyone installed similar windows and can share experiences? Or how does the actual light yield compare between the two variants?

Many thanks for assessments/opinions.
Charly

Stulp and mullion do not differ that much in terms of light yield. By the way, there is a third option: one window section fixed glazed and only the other openable. This might possibly be the most cost-effective solution.

Whereas cleaning with fixed glazing, except on the ground floor, is always more complicated than a window that can be opened.

Where is the light yield supposed to come from? Both the mullion and the transom have 2 sashes - whether there is 1 or 2 cm more or less frame there does not matter.

Whether the brightness in the room is sufficient, of course, also depends on the orientation, as well as the room color or furnishings.

I would make the width measurement dependent on the external appearance.

Regards

Now just the question, are [Stulp windows] still suitable here for better light yield or windows with a central mullion.

In terms of light yield, they should not differ measurably. With [Stulp] you can only tilt one sash and can only open the "second" sash after the "first" one. With a mullion/central post, you can tilt and open both sashes independently. With [Stulp] you can create a large opening, with a mullion you have two openings side by side.

Hello and thank you very much for these initial assessments.

As mentioned, the vacant windows are the second ones in the room and therefore actually not relevant for ventilation. Additionally, we have a controlled residential ventilation system in the house.

It was also a bit about practicality, as we want to place the desk under the window, at least under one half of the window, and thus only one side of it – if at all – will be opened. Fixed windows are not an option because of cleaning.

Has anyone installed one or the other option in their house and can say if it is good/bad? Especially since a fall protection must be installed on both variants due to the [BH].

Thanks and best regards
Charly