These houses apparently have a bad reputation regarding insulation and heating. I would be very cautious whether anything can be achieved without major renovation work. This should definitely be taken into account when looking at the purchase price of the house.
For heaven’s sake, I don’t want to denounce the company name V., but if you know more about these construction years, always share it, preferably as a private message. It really started back then with the whole "energy transition" and "new concepts." Keyword: beautiful old buildings were "senselessly" insulated so that they then mold inside and need ventilation. If only they had left the beautiful wooden windows...
The Viebrockhaus is a kind of solid prefabricated house? Like segments at the bottom? The focus in my case is on the upper floor, supposedly timber-frame construction from the outside, also clad with bricks. The roof structure, exterior, and interior all look very high quality. I have rarely seen such good conditions for the age in existing buildings. The only thing you can’t find online is anything about the wall construction, hardly any photos. How thick is the brick cladding, how thick the insulation then? (Any harmful substances?!) Interior paneling?