Assessment & assistance semi-detached house, approx. 180 sqm in DIY floor plan

Ok, so I understand correctly that it is better if the air heat pump stands at the bottom left in front of the house (facing forward) and the cables then run zigzag upwards instead of straight up?

No, in my plans there is no zigzag routing of cables. Cable ducts run straight up where they do not interfere (->middle wall)

there is hardly any space left for a cabinet.

The middle wall. However, you lose cabinet space due to the edge position of the doors on the right side of the plan.

As far as I know, there is a mathematical formula to calculate how many sqm of window area you need for a certain room.

That is pure theory and applies as a minimum requirement. I want to mention that it is _your_ wish to build in an airy and spacious or similar appearing way…

Where could one incorporate an open sightline?

I already posted that on the ground floor. Yes, it was an attempt with a gallery to capture roof light, but it does not have to be realized.

Yes, I expect some investment when I am asked for a signature that costs 500k and will be the biggest investment of my life.

Cheers to your expectations. We remain curious whether they will be met by a general contractor.

Here’s to your expectations. We remain curious whether they will be met with a general contractor.

Yes, there will probably be a learning curve. What can you expect from a first offer? Definitely, no one will create a detailed floor plan for you. Not everyone is as crazy as we are – sellers have to sell, not entertain. If you’re lucky, the provider already has 3 plans in the drawer from former clients who built something similar. They’ll scale one to your size, maybe move 3 walls, and you’ll get a proposal. But most will only present measurements, maybe a sketch of the ground floor that you designed yourself, and give you a price estimate. Otherwise, it’s mainly about feasibility in terms of materials, execution, time, land, zoning plan, and the like. An architect only comes into play if you pay for one.

If that’s important to you (for me, for example, it would be), you first take the architect of your dreams and have them create the design upfront for (a lot of) money. That can take some time. With the result, I then shop around and ask the building companies who can implement this concrete project. But many new homeowners are discouraged by the initial costs and then take some third-rate crap that an apprentice drafter quickly scribbled somewhere and fumble around as amateurs for weeks.

I imagine that would have an outdoor unit hanging on his gable wall.

Nope… it stands on the ground at the side parking space.