How to obtain an exemption from the development plan?

Regarding the actual topic: What really hurts me is the massively lost space.

Then the task is: How do I make the space between knee wall and knee wall usable.
Here are some ideas:

[*]Put in a small door and use the space as storage for rarely used items - e.g. seasonal decorations (Christmas, Easter...) or winter clothes or...
[*]"Secret" connecting tunnel with a hiding chamber between children's rooms. What kind of play joy the "dead" space suddenly offers!
[*]Sliding doors in front and use it as a horizontal cabinet
[*]Fancy a "scribble-worthy" terrarium?

We have cut out some space on our gallery above the cooking area and created a knee wall with storage space behind it. That works great, although for me as an "old man," crawling in and pulling something out is a hassle. But only rarely needed things are stored there.

I like the idea! I'll give it some deeper thought.

What might be problematic is that in such a "storage closet" there is no real air exchange. This could become problematic regarding mold. Otherwise, I would have to include the room in the controlled residential ventilation.

I find the idea of the built-in closet (partially) instead of a knee wall sympathetic, whereas I no longer suggest the idea of a breakthrough into a crawlable recess in today’s energy saving regulation era, as this seems to me more complex for the creation of the thermal envelope boundary than the storage space gain would compensate.

What might be problematic. In such a "storage closet" there is no real air exchange. This could become problematic concerning mold.

In our wooden house, this is absolutely not a problem. In the knee wall chamber, there is no moisture buildup. However, under the knee wall chamber, there is only a 5cm wooden floor, which also forms the ceiling above the dining area - this construction is probably more solid in your case.

Ok, something like that has to be told to me by the architect or the [GU], whether it's feasible or if there could be problems. Overall, I find the idea quite charming to make another "storage room" out of it. That way, each child's room could get its own small storage closet. And the actual storage/workroom will be a bit bigger. It would then just get a partition wall or something. My neighbor, with whom we have a good relationship, is a carpenter. He might have good ideas for it and can possibly implement it if it gets too complicated for me.

The implementation is very simple: wooden frame and Fermacell. Insert door or flap, finish surface (paint, plaster, wallpaper...). Done. Inside, you can see the wooden frame. So what. Minimal costs.