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

1) Comfort gain! Living in a well-insulated house is a huge comfort advantage. Even temperature, no hot/cold spots in the house, no cold radiation through walls... it is significantly more pleasant to live there.

Well, I have already lived in (not exterior insulated) houses and apartments from the 60s, mid-80s, and early 2000s. It was nowhere uncomfortable. As long as there are no drafts and the heating works, I couldn’t have noticed any difference blindly... Maybe I’m just not sensitive enough.

2) If you calculate economically, you have to consider the value of the house, as has already been written.

Of course, the value of a house increases with modernizations. Sometimes by the value of the modernization costs, sometimes more, sometimes less. But why should I consider that "additionally"? And if you don’t want to sell, then you can nicely bake yourself an ice cream from it.

So I've already lived in (non-exterior insulated) houses and apartments from the '60s, mid '80s, and early '00s. It was uncomfortable nowhere. As long as there is no draft and the heating works, I couldn't blindly tell the difference... Maybe I'm just too insensitive.

You get used to everything, I would say. Stand next to a 60s wall at -10 degrees outside. The room temperature may show 22 degrees, but due to cold radiation, it still feels cool near the wall (at windows it is of course even more extreme). With a well-insulated wall, the room temperature may only be 20 degrees, but the perceived temperature is still higher and it feels more pleasant because there is no cold radiation.

Of course the value of a house increases with modernizations. Sometimes by the value of the modernization costs, sometimes more and sometimes less. But why should I consider that "additionally"? And if you don't want to sell, you can then nicely bake yourself an ice cream with that.

If you personally don't care about the increase in value, are not interested in what happens to the house after your death, don't care about or don't notice the comfort gain, then your calculation of course is correct. But this is a special case. For a general calculation, you simply have to consider all factors, even if in your personal case not all factors apply.

For example, if you inherit the house to your children, they receive an increased-value property. If you want to sell the house during your lifetime, you get the increase in value yourself. In these cases, the increase in value must be included (unless of course you don't care about what you bequeath and what not).

But why should I consider that as "additional"? And if you don't want to sell, you can nicely make yourself an ice cream with it.

Because the money is not consumed, it is invested. One reason why the formula "investment vs. heating cost savings" is incomplete.

Example(!):
The measure costs 21,000€

6,000€ come from KFW as a grant
5,000€ would have been the cost for the anyway necessary facade renovation
5,000€ heating costs you save in 10 years
5,000€ increase in value the property gains

It's worth it, and big time.

I consider this to be a classic case of "fudging the numbers," but I accept the opinion.

By the way, if mold on the inside and moss on the outside occur, you have to open negative positions again.

Oh, and: the next facade renovation will cost (based on this example here) just as much plus significantly more for disposal in 35 years. And we are still talking about a 20% heating cost saving. So unfortunately, I still have to shake my head...

I still don't quite believe it. Insulating the facade makes sense, but it also has to be cost-effective. Maybe it pays off more if you only do 5cm and don't have to rebuild the roof or similar? And why can't a "strip" simply be installed between the roof and the insulation to keep rainwater out? That would probably be cheaper.

I would first inform myself whether a new heating system or something similar isn't cheaper or simply offers a better price/performance ratio. Replacing a 15-year-old oil heating system with a new one is supposed to save 15 to 20%. With an amount of 20k €, you could certainly go deeper and maybe get 30% out.

I think I need to inform myself about a new heating system.

So you don’t save 15-20% just by replacing a heating system. The operating mode has to be adjusted. And the old heating system already saves there.

Whether the insulation of the facade is worthwhile depends on other circumstances. If the facade has to be done anyway, it is probably worthwhile.

The increase in comfort should not be underestimated.

And no one knows if, how, or what will happen in 35 years. So this can neither be an argument in wild price forecasts nor regarding disposal or the durability of the insulation.