Single-family house approx. 150 sqm floor plan - How to plan the staircase?

Don't you want to make the windows generally a bit wider? Especially at the top. We have 1.80m wide double windows and I would definitely call those rather small.

Regarding the storage room or utility room upstairs, I am going back and forth... Disadvantages from my point of view: very small, cramped corridor upstairs and no access to a possible skylight. The advantages of a small utility room upstairs are of course obvious... we'll see! And the windows have not been finalized in width at all, just rough estimates so far of how it might fit. Do you mean the floor-to-ceiling windows in the children's rooms and the living area or all of them?

If I mirror the stairs, I have to automatically move the front door to the right.

That should be doable. Then the side panel would just be under the carport.

What does the mirrored staircase have to do with the carport?

You shouldn't really get into any discussion without a site plan [emoji23]

If you, @manyyou, are planning a house with sloped ceilings, you should aim to make the most use of these areas for living or bedrooms:
You can put a bed underneath, build a hideout, box off the knee walls, or put deep cabinets with sliding doors in front, so-called space wonders. Or it is more or less dead space for adults. If you assume €1600/sqm, quite expensive.

Where is the bed supposed to be? Under the window? Further to the left? And what is supposed to go on the right then?
Can you afford the luxury of not planning anything under the slope?

The staircase has the most important function in a house - everything else depends on it. Three meters on one side is not balanced if you have to plan three bedrooms.

Yes, if the bed is actually supposed to be placed like that, you need a knee wall of at least 1.50m, I think. 1m would be too tight for me, even if I put the bed directly under the slope. I had that on vacation. Terrible! 2x a bump on the head when waking up!

In the 3D representation, the whole thing looks like this to me with a 1.15 knee wall and 43 degrees

If I'm not mistaken, that should fit, right? ... and a nice large dresser would be possible under the slope