Baunebenkosten calculation realistic?

I'll join in.

Gladly and interesting view.

Predicted savings compared to KfW 70, the basic standard. Water 0, wastewater 0, electricity near zero, gas around 100,- p.a.

Wastewater/water, logical. But can the energy savings be substantiated or calculated with figures?

The additional cost would have been around 16. Plus tax that also comes close to 20. Projected savings compared to kfw 70, the basic standard. Water 0, sewage 0, electricity close to zero, gas around 100,- per year. So, now calculate for yourself. That’s throwing money away, that kfw 55 nonsense.

Oh well. The calculation isn’t that simple.
You have to factor in that the KfW 153 loan usually has a lower interest rate than a bank loan. Plus the 18,000 euro repayment grant.
Now there’s still the question of gas or heat pump.
No one knows how gas and electricity prices will develop in the future. Your calculated 100 euro savings is a snapshot. The CO2 levy is certainly not included either.

Coal and nuclear are history. Gas remains the only reliable energy source. Supply mainly from abroad.... With a heat pump and a roof full of photovoltaic panels, you at least gain some security.

...but then definitely a relatively large-sized storage system for the photovoltaic system. If independence is important to you.

But it has nothing to do with KfW 55...

I'll jump in. Our renunciation of kfw 55 back then calculates like this. The additional cost would have been around 16. Plus tax, that's close to 20. Projected savings compared to kfw 70, the basic standard. Water 0, wastewater 0, electricity close to zero, gas around 100,- per year. So, now calculate for yourself. That's burning money, that kfw 55 stuff.

What is included in the approx. 20 k€? If it is an air-water heat pump, 35% of the costs are refunded. There is an 18 k€ subsidy from kfw after all. I think it's definitely worth it.

Repayment grants and money from them I did not want. Otherwise, the more things differ, the less favorable the calculation. With an air-water heat pump instead of gas, the 16 net would never have been enough; another 10 would have been added. PI again a considerable surcharge. Then you always have to save more and more energy. Don’t make the calculation look good for yourselves; it is an idealistic, not an economic decision for this kfw 55 or better.