Advantages of KFW 40 Plus in General

I think you still forgot decisive points here, such as higher planning effort and the building envelope with insulation, windows, etc. I would calculate at least €20,000 more for these in a large house (200m²).

Thank you very much for your assessment. In our specific case, however, the planning effort is likely to be relatively low. According to the first calculation, the insulation would only need to be increased by about 15% (e.g., by insulating under the concrete slab). The windows are already at the required standard anyway (good contact with a window manufacturing company). It still seems, however, to result in a long amortization period.

Away from the economic aspect for a moment:

A Tesla is not profitable either, yet they sell like hotcakes.

With a Kfw40+ house, or even a positive energy house, you are part of the solution, not part of the problem.

A new building that only meets the energy regulation is a newly built old building.

And back to the economic aspect: Due to the photovoltaic system, yesterday I had costs for heating and hot water, 300m² living space at 22 degrees and 3 people showering of: 3 cents.

THAT WAS NONSENSE WHAT WAS WRITTEN HERE

We actually chose everything without paying much attention to the Energy Saving Ordinance and now have something better than KFW55. Anything below that would have caused massive additional costs for us, as you have already nicely broken down. Even with KFW, it would never have paid off within a reasonable time frame. KFW was never really an option for us anyway, since last year the bank's interest rates significantly beat the KFW rates, and unfortunately, no prepayments are possible with KFW anymore. (We would have saved over the term with KFW more

A photovoltaic system with storage for 15,000 is also ambitious. Build a photovoltaic system on your roof for self-consumption & feed-in (the power grid is the best storage anyway) and wait 10 years until decentralized storage might eventually become profitable.

And back to the economy: Due to the photovoltaic system, I had costs yesterday for heating and hot water, 300m² living space at 22 degrees and 3 people showering, of: 3 cents.

With layered buffer storage or which configuration do you have?

Away from the economic aspect: A Tesla is also not profitable, yet they sell like hotcakes.

Unfortunately, that does not mean that it makes ecological or economic sense.

With a Kfw40+ house, or even a positive energy house, you are part of the solution, not part of the problem.

The same applies here first of all. Production initially involves higher energy consumption, also due to the transport of additional materials, etc. Are there precise calculations on whether this is compensated within 30 years?

The invoice is always individual.

- What is "already there"? If a controlled residential ventilation system is planned anyway, there are no additional costs that would have to be charged.
- Photovoltaics pay off by themselves, storage does not.
- Are the additional costs fair? A bit more insulation doesn't cost the world, but if you build with a general contractor who wants to charge a fortune for it, that can ruin the calculation. Those who build with a timber frame basically have the "KFW 40" wall as standard. Those who build monolithically invest more and lose space due to fortress-like walls.
- An air-to-water heat pump would also work; it doesn't necessarily have to be a brine-to-water heat pump.
- If the overall concept is coherent, the brine-to-water heat pump becomes cheaper because the drilling can be shorter.
- Are the KFW conditions attractive? The last two years the conditions were bad, but now they are good again and in some cases better than bank loans.
- Do you believe in rising heating costs, regardless of energy carrier? If you consume little, these increases don't matter to you. The resale value can also be increased – from 2021 onwards, only passive houses exist, where KFW 40+ is very close to that today. Have a look at new builds from 5 years ago on Immoscout, what energy values they have and how KFW 55 stands today ... that impacts buyers' minds.