How do you finance the million-dollar house? (BW, passive house, 140+50 m2)

No, rather also in this size.

Hey, it seems someone here is really well connected in terms of the Barthel method. When talking about existing large plots, hopefully it's with the owners. There surely must still be people who sell to BRW, for a friendly neighborhood and not to the highest bidder lawyer with the SQ7. Regarding financing: If you understand the house as a consumer product, you COULD do something like that if the bank cooperates. For me, it would be too big a burden to constantly have the refinancing and the secure sale in mind. If you are really aware of all the consequences, I would only do that with an existing property where possibly floors and painting still need to be done before moving in. For a temporary situation, all the construction stress — I would be out of the game after 1.5 years with a heart attack.

Have you already been to some house providers and roughly calculated what a house as desired would cost you in your region? Fortunately, Stuttgart is still nowhere near Munich, but from what you hear, prices have also risen quite a bit where you are. From experiences in my circle of friends, I can only give you the following tips if you want to manage the house project and still sleep well at night:

- Calculate the option of a granny flat/2nd residential unit thoroughly, usually it’s not worth it and most people do not want to rent to strangers in a single-family home. As far as I know, this 2nd residential unit must really be proven, meaning you absolutely have to build a second entrance, bathroom, kitchen connection, etc., which costs a lot of money.
- 190m2 seems absolutely utopian for the price to me; look at houses with 160m2 or 170m2, which always seemed more than sufficient for 4 people.
- Passive house, minimalist, ecological: With these 3 buzzwords, a lot of money is currently being made in our region because it suits the zeitgeist. For me personally, the benefit seems very questionable; even a KFW55 house with possible photovoltaics has above-average values, conventional building materials must not be unhealthy either, and minimalist aesthetics do not necessarily mean cheap, but rather a reduced and classic design-oriented look. House providers like Regnauer and Baufritz specifically target this buyer demographic, but for me the added value is not apparent; you pay an extremely high price for the ecological label here. If you can and want to afford it, sure, everyone as they please, but if the financing is tight, I would start here first and rather give the children a bigger room than an extra ecological insulation whose benefits you can't really verify.
- Income side: From a gut feeling, I would guess that with some luck in the land search you can afford a solid and nice house, but the days of a Ferrari-sized house with a granny flat are long gone even in Stuttgart, although the total volume is actually insanely high (unfortunately!). In my circle of friends, I have noticed more often that a very high loan has psychologically burdened the men quite a bit after some time when the women were still on parental leave or couldn’t really contribute. Therefore, I would personally think again here about how the sum feels to you as an almost sole earner, whether the risks can be well insured (disability, sudden death, long illness ... none of which you want to think about but can happen to anyone), and whether your wife can start working part-time again sooner or later. Nowadays, it’s easier to coordinate this with children thanks to home office possibilities, maybe this will let you sleep a little more peacefully and involve both partners in the house project.
I wish you definitely much success and luck in the land search and then in the construction!

So if you can't afford it, you should rather plan a house with 120 sqm. That is more than enough for parents and 2 children. And why have an apartment that you rent out?? You also have to take care of those square meters (repairs, vacancy...). Apparently someone wants to live large even though the income situation doesn't really allow it. Even if you have a relatively large plot of land, that really doesn't mean the house has to grow proportionally. A small house and a big garden is much cozier and also nicer. And it means less work if you mostly have lawn. Your wife will be thankful to clean 150 sqm every week. I would think about the whole thing again...

Above all
Passive standard - doesn’t really have to be now
To be

What do you intend to do now?

and minimalist design does not necessarily mean cheap, but rather refers to a reduced look oriented towards classic designs. Home providers like Regnauer and Baufritz specifically address this group of buyers,

Uh, yes, that is then already "mid-elevation location" in terms of price :)