Draft for extension/conversion of single-family house to ZFS

Why don't you use the "parents" part and renovate your parents' half to be senior-friendly?

That was also our first idea, but unfortunately the space on that side is very limited. Due to construction restrictions, building up to the boundary is not allowed, and the north side is the "ugly" corner of the house: no sun, street, driveway to the neighboring property, large/tall neighboring house, very loud heat pump directly on the other side of the street. Therefore, no one wants to have large windows or living/bedrooms there. Considering the "must have" for my parents—large windows in the kitchen, living and bedrooms, as well as a guest room—it is difficult to arrange all that on one level there with the available space. Because my parents also really like the conservatory and the current ground floor, it is easier if they keep that part; with the additional upper floor, we have a bit more design flexibility.

Remove the corners and edges at your parents' place.

And the front area needs to be redesigned at your place.

I find the usual semi-synoptic redevelopment plans really much easier to overview. Besides, the new facade design / window layout alone drives away the 80s charm :-(

Unfortunately, I do not have semi-synoptic plans.

By the way, the new facade design / window division alone takes away the 80s charm :-(

Do you mean the wooden cladding on the gable in the drawings? That was only a suggestion from the planner, which is not intended to be implemented.
I have attached a picture of the old facade.
After the conversion, the facade is supposed to look more like the original state again, but without the overgrowing ivy.

But the multi-pane windows have to be discarded because of insulation value and cost.

I have tried out various options to redesign the ground floor again.
Attached are 3 versions (and a sketch of how it could affect the upper floor).
However, I am not sure if this is even progress compared to the original design, or in which direction it is worth thinking further.

One disadvantage that all versions share is that the floor plan would be 1.25m longer towards the southwest and the terrace would thus be relocated to the southeast.
Together, ground floor and upper floor would be about 13 sqm larger (correspondingly more expensive?).
In addition, although the living space becomes more open/nicer, there is partly a lack of storage space (smaller pantry/wardrobe) and the kitchen would have no direct window.

Do you perhaps have any opinions on which design is heading in the right direction? Or is it all rather a step backward compared to the original design?

Not really better. OG bedroom passage room Game gallery nothing other than rest EG your part Stairs somehow needed Parent area still too many corners weird annex as hallway with cat table swap the areas. Annex can get a conservatory again