Build before or after 01.04.2016?

The repayment calculator has also been adjusted.

30 years fixed interest rate is not possible. You probably mean the term. It is possible to have a fixed interest rate for 10 or 20 years.

I have also been very eagerly waiting for it and the result is pretty much exactly what we expected and assumed in our preliminary calculations. Secretly, I hoped for better numbers, but you also don't want to be ungrateful, after all, you can't get this much money anywhere else at this interest rate. The 1.3% is of course another nice incentive to pay off faster, but you also need to have enough free capital for that. Since we want to finance 2 residential units through the KfW, we will probably play it safe and plan for a 30-year term.

I am currently going through how this would affect us financially:

We need a loan of €300,000. If I were to use KFW, with a 20-year fixed interest rate, we would save almost €8600 including the repayment bonus. Honestly, I expected a bit more ^^
But that’s probably also because we already have a relatively low loan-to-value ratio, so when using the KFW loan, the interest rate of the normal loan can’t change much.

In comparison, Gas+Solar vs. Air-Water Heat Pump, it is likely to come down to the same investment costs based on initial calculations, especially if I include the €2,000 technology bonus from the 10000-Houses Program.

Since we wanted a ventilation system with heat recovery from the beginning and have always planned a separate budget for it, I think I can interpret this as putting the entire savings from the KFW loan into the better building envelope.

If I then assume that through KfW 55 I save about €40/year on heating costs compared to the “normal” building envelope, I would arrive at an amount of €8600 + 20x€40 = €9400.

I will discuss this with the architect today to see what he thinks.

At my bank, I get the remainder for 1.85% (20 years fixed interest as full amortization) with a subsidy of 0.25% of the KFW conditions.

What do you mean by a subsidy of 0.25% of the KfW conditions?
The remainder would normally be 2.1% and you get it for 1.85% because of KfW?
If yes, do you have an overview of banks that offer such a bonus?

It's a pity that between 20 and 30 years term of loan is distinguished. 20 years term

At my bank, I get the rest for 1.85% (20 years fixed interest as full repayment) with a subsidy of 0.25% of the KFW conditions.

What does subsidy of 0.25% of the KfW conditions mean? The rest would normally be 2.1% and you get it for 1.85% because of KfW? If yes, do you have an overview of banks that offer a bonus for that?

It's a shame that there is a distinction between 20 and 30 years term. 20 years term with 2 repayment-free years and 5% bonus equals about 5% repayment. Theoretically, 30 years term and 2 repayment-free years should also be possible? Then you have a repayment of just over 3%. You can make as many extra payments as you want anyway, so you could be paid off in about 25 years.

The Allianz insurance, for example, offers a 0.25% discount on the KfW loan. That means the KfW interest rate for program 153 with a 20-year fixed interest period is 1.3%, then you get it at Allianz for 1.05%.