Weighing different options in the single-family house

If you omit the heating loops there because of the bathtub preparation, you will constantly have cold feet in that spot even in winter. That must not be forgotten.

If you don't want a tub, don't install one. A buyer in 5, 10, 20 years will just have to accept that.
Are you building the place for yourselves or for resale?

Unfortunately, you can only edit for 4 minutes... that’s why another post about the utility room. You are planning without a basement. You have no space for basement replacement rooms in the outdoor areas. You cannot plan a large attic. You have very little storage space in the house and will be happy for every meter of shelving you can fit in. Don’t underestimate how much space the building services can take up and especially how much the pipes above the appliances consume. Simply hanging a shelf above the [Kontrollierte-Wohnraumlüftung] is not an option. An extra door or a second sink are luxuries you simply cannot afford.

And also does not need it. You can cover the path from the carport to the front door, there are possibilities ;) It does not rain that often anyway and a paved path just gets wet, but after the construction phase it will no longer be muddy.

(16) Second front door from the carport to the utility room Decision: Still open Reason: Would be a nice feature to bring less dirt into the hallway (children, groceries, drinks) and to come dry-footed from the car to the house and vice versa in case of rain; however, the two doors are also only a few meters apart, really sensible?

Then you bring the dirt into the room where laundry for 5 people is done. The waste of space has already been mentioned.

(12) Bathtub Decision: No bathtub in the upstairs bathroom, but prepare connections for possible retrofitting and use for washing machine Reason: We are not bathtub fans and would like to save costs; however, we would still provide for pre-installation in case we change our minds or for a higher resale value

Retrofitting is pointless. A tub goes into the screed, not on top of it. Otherwise, it would be too high.

You plan for the next 20 years, not just for now.
An occasional muscle relaxation or cold bath, baths for therapeutic purposes, during illness or preventively, soaking hand laundry, rinsing blankets or bathing for hours (yes, people do that), letting Christmas carp swim, dyeing clothes, bathing the dog, collecting laundry, craft work, etc. Foam baths are fun for children. You have the space; you can also furnish it with the tub. The builder's credit hardly pays out anything anyway.

A cheap house is now decorated and upgraded like a Christmas tree, but, but when it comes to the tree topper, savings are made.

Flooring and painting work can be got much cheaper from a local provider

That is charged separately anyway.

You will be amazed at how low the credits are when you remove something. And you can almost forget about the warranty then.

Thank you very much for the many responses and opinions so far.

You actually took the idea of a door in the utility room away from me. That makes little sense, especially because of the parking space.

Regarding the cable connection: Although the internet does come into the house via that, the outlet in the utility room with the router is sufficient. I can then still do without all the sockets in the individual rooms since Ethernet is available. Although I also don't know how much the credit will be in that regard.

You also have good arguments regarding the bathtub. We would possibly plan with the washing machine and dryer in the bathroom instead of the utility room. That would then also give a bit more space in the utility room.

I'm still uncertain about the security classes of the windows. I need to study that more thoroughly.

Invest the money in RC2, then you are on the safe side. Everything else is half-baked rubbish that you then try to compensate with motion detectors, floodlights, cameras, and an expensive alarm system. I have RC2, no outdoor lighting at the moment, and everyone sleeps peacefully even when I am away on assignment for 3 weeks. And yes, two streets away there was already a break-in shortly after the new buildings were occupied.

Washing machine and dryer in the bathroom are of course also not bad, that way you could use the space reserved for the bathtub sensibly. The movers will definitely curse ;)

And about the space. We just upgraded from a 1.5m dining table to 2.6m. It was full before and is full again now. I mean: The more storage space and shelf meters you have, the more stuff you accumulate and acquire. It is not impossible to live with 4 people on 120m², it used to be possible anyway.