KFW 300 Funding - Attractiveness

Do I see it correctly that with the KFW300 with a 20-year fixed interest rate, the interest jumps to around 2.7x%? Then a lot of the interest advantage would just be gone (especially for you with a good loan-to-value ratio).

This is just a guess, but I suspect that if you put in over 50% equity, the remaining loan after 10 years (even if it's only 8-9 years of repayment) will be manageable and I also simply assume that the loan for you might not be as "tight" as it is for some others. But yes, in case of doubt, just calculate it.

As a disadvantage of an EH40, the claim was made that no large glass surfaces would be possible, especially facing north. And also constructive components made of concrete, like the beams suggested here. However, from my own experience, I can say that this is nonsense. Beams, reinforced concrete columns, and much more are not relevant in the thermal insulation calculation. If your house has 100 sqm of window area, then the reference house also has that. You just have to make sure to choose windows with a low transmission heat loss. If the desired windows still have a slightly higher U-value, that is not a problem either, just compensate elsewhere (e.g., roof). The orientation of the windows plays a subordinate role in this. If you comply with the transmission heat loss of the entire house, then the heating energy demand usually fits as well.

Does anyone have an idea how we should best proceed regarding the KFW300 loan if it is not clear which heating concept ([Großwärmepumpe für alle Haushalte von Seiten d. Stadt] or [Einzelwärmepumpe]) will be implemented? Basically, both meet the requirements.

Does anyone have an idea how we should best proceed regarding the KFW300 loan,

Ask the energy consultant. He has to give his confirmation. Let him say how he wants to calculate. Changes during the construction phase are not a problem, as long as he can confirm at the end that the data made at the beginning are adhered to (KfW40 standard).

What exactly has to be done for the BzA, is it just a form to tick off or do the complete LCA and all other calculations already have to be completed for it?

What exactly needs to be done for the BzA, is it just a form to check off or do the complete LCA and all other calculations already need to be done for it?

Complete calculation of the house's efficiency. So it must already be fully planned.