Additional positions in house construction: are they useful and reasonably priced?

then this central solution is not worth it with the surcharge in 100 years.

In that respect, I agree that he is waiving this expensive fun and instead aiming for the decentralized variant at a fraction of the cost.

Sorry, but here it is about dissipating energy to the outside in order to bring it back again.
Heat pumps and photovoltaics are not a guarantee to (again) mess around with energy just because you can afford it.

The central ventilation should not be considered only from a cost perspective. It is comfort (also e.g. pollen filters against allergies...), which later cannot be retrofitted in this form (or only with immense effort). Prefer carport over garage, but central ventilation instead. But yes, everyone has different priorities. With stone-on-stone construction, keep in mind that you may have moisture in the building for over 2 years that needs to be removed (my personal experience with a new rental apartment). And not all life circumstances allow for sufficient ventilation (12h out of the house ;-) ) I would never go without central controlled residential ventilation again (others, however, have different opinions as mentioned above)

Why can I only use a pollen filter in the central ventilation, not in the decentralized one?
Why do I need the pollen filter if I don't have allergies?

You don't have to have moisture in the building for 2 years during construction; it can be dried.

I don't understand ypg's comment at all. Does he/she believe that a decentralized system has no heat recovery?
In that case... at what level are we discussing here? Lay helpers-helper-apprentice?!?!?

I don't understand ypg's comment at all. Does he/she believe a decentralized system has no heat recovery?

My answer is not about decentralized or centralized. You don't necessarily have to read carefully to see what I responded to, and my answer applies… tada… to manual ventilation, which the OP favors in his answer. Your #22 with my quote has nothing to do with my answer.

In that case... at what level are we discussing here? Lay helper's helper apprentice?!?!?

It's about addressing questions and not blindly using buzzwords, giving an opinion that does not address the question.

We also have tilt-and-turn windows. I think they are great for floor-to-ceiling windows that you go out through. I wouldn’t do it again for normal windows because you always have to open the one fixed window first, and the second window doesn’t have a normal handle but an inward-lying kind of latch. It’s not a big deal, but I wouldn’t pay extra for it.
We also have a side entrance door in the utility room. And I wouldn’t want to miss that. When we are at home, it is used more than the main front door because it leads directly to the back garden area, garages, and sheds.
Regarding the sanitary fixtures: you have to decide what you like and whether you can get something better for the price. I think you can.
The same applies to the stairs, it’s a question of what you prefer. I have a bungalow but also know houses with stairs. And I would always prefer an open wooden staircase if I didn’t necessarily need a closed space underneath, because it simply looks lighter and more open. A friend of mine has a concrete staircase with closed sides, which to me looks like a prison.
Tongue-and-groove boards can be easily installed yourself; you have to see what you can get yourself. Last year we paid 10 euros per square meter, but directly from the sawmill, found via classifieds.
You have to talk to the respective craftsmen about all the small jobs. Ours refused to do anything that wasn’t done through the general contractor because he forbade it and they wanted more jobs from him.
Whether you need a laundry chute, I can’t say because we have a bungalow. But I think you just go downstairs anyway and can take the laundry with you.
We also don’t have a ventilation system. I don’t know it and don’t miss it. Does it save a lot of energy? It also uses energy itself, even at times when not heating. You would have to look into that. At any rate, we achieve a good indoor climate with normal airing. I might be somewhat critical if really both partners are out of the house for 12 hours a day (but then again, the question is what you need a house with a garden for;)).

I would reconsider point 1. Does that mean you buy the material and install it? How does liability work in case of damage?