Facade insulation for a semi-detached house: what/how must be approved by neighbors?

It seems to me that the naive visual idea is widespread to associate facade insulation as a kind of muffler for the pain scream when looking at the heating bill. Actually, one should consider the overall situation as a system - the problem is that so many parties are involved in the measures, each of whom only has a single component in their product range and wants to attribute the lion's share of the effectiveness to it.

Personally, I find it difficult to imagine that for a building year 1985 (old federal states) there could really be a big saving to be made economically. The standard was no longer below 36.5 cm monolithic - however, there were still radiator niches without underfloor heating. Cavity insulation between rafters was already common. The windows could have potential, provided they are still original.

...the problem is just that there are so many parties involved in the measures, each of whom only have a single component in their product range and want to attribute the lion's share of the effectiveness to it.....

That's how it is, which is why the entire system must always be considered, as has been said several times before. When I read again... "first see if the heating can be economically replaced"... yes, that is simply the completely wrong approach. Through insulation (and the facade has the greatest leverage here) the heating demand is sometimes reduced enormously, which leads to a smaller heating system, which again saves money.

Considering only individual measures is too short-sighted; in this way, you ruin your beautiful house and end up paying extra on top... A holistic consideration can certainly show that it only makes sense to replace the heating system, but it can also be the case that a complete insulation including heating makes sense, or only the roof and heating, or one of the other hundred possible alternatives. There are corresponding energy consultants who can develop an "objective" appropriate concept for you.

There are appropriate energy consultants who can "objectively" develop a corresponding concept.

Unfortunately, there are quite a few fools in this field who feel qualified after weekend courses lasting four weeks. The result is that the customer thinks even the professionals have no clue. The business is then made by the one among all the individual component sellers who already has the funding application with them ;-(

As soon as you step even one centimeter onto the neighbor's side; he has to approve it. So just ask and if he objects, it simply only goes up to the boundary.