House purchase single-family house built in 77 how to assess?

I am certainly curious to see how it will continue, if you want to keep reporting, and I wish you that it works out and your acquaintance keeps his word.

"This existing prefabricated house was built around the end of 1970. The manufacturer at that time was the company Streif Haus. The building envelope of the house, consisting of the roof, windows, and facade, was overall very aged. The ground floor is fully clad with a ventilated facade system using an asbestos-containing plaster carrier board. On the upper floor, the gable sides are clad with dark profiled wood as a visible covering."

Could fit... the current house attached as a comparison image...

I have to say, the whole house already looks much friendlier this way. You can definitely renovate it nicely and also bring it up to date. I would do it, but only if I could manage the renovation financially without my acquaintance. Because in times of inflation, I wouldn't rely on words unless there is a written contract. No matter who it is from. Whether a friend, an acquaintance, or anyone else.

A note regarding the electrical work: we completely redid it. There was no RCD and two floors were on one (!) 16A fuse. The whole house had 12 fuses, which is definitely not sufficient nowadays. At first, we didn’t want to redo everything, but no one would have expanded the electrical system either, because the legal protection of the old installation would have been lost and we would no longer have been allowed to operate it. Now we have rewired the house, installed networking and prepared for photovoltaics, a lot of dirt, cost around €16,000. We are glad we didn’t do this while living in the house.

I experience it rather differently: heirs who are already (not particularly wealthy) retirees themselves face energy modernization obligations and the house bank suggests a sale. These are then not outright market properties, but calling them "junk properties" is a bit harsh.

There are no energy renovation obligations, only if there is a conversion or new construction. Even the old heating system may remain if the values are met and the owner does not change.

Uhm, inheriting is not a change of ownership? It's not a sharp question now, it could be environmental law-related...