Single-family house from 1950 with backlog of renovations "Charm of the 50s" - renovation costs

The energy consultant will tell you, it certainly depends on the walls. The recommendation will probably be "YES" in most cases. The energy consultant comes by, takes photos, and asks for construction documents, and in the end you get a protocol with individual measures showing how many percent of heating energy you can save per measure. These then include things like "new front door" and not just the big stuff. There are certainly houses that could be insulated, but then you completely ruin the exterior appearance. Then you might save yourself the 30k for facade insulation, switch from an air heat pump to geothermal for that money, and add an additional 10kWp on the roof. You need the consultant anyway in the end, because you only get funding if you follow your renovation roadmap.

I was rather advised against KFW (subsidies), as they are not really individual and more expensive than a classic loan.. I had already raised the question whether KFW should always be involved with such a renovation (to reduce costs)?

I was rather discouraged by KFW (subsidies), because it is not really individual and more expensive than a classic loan..

BAFA, not KfW Federal funding for efficient buildings. Implement measure from the roadmap. Pay. Then get 30-40% back.

That's the point: Isn't it true that only certain manufacturers are listed on the Bafa list,

In addition, I would have to prove every step with an invoice.

This is actually the first time I’m hearing that. So I would initially say no :)

Correct.
The advantage is that you don’t have to do everything at once, but can carry out a new measure every 2 years, which is also doable.

KfW 55 funding was discontinued, their focus now seems to be on existing buildings. So a lot could change again in the next 2 years.