Build a multi-family house according to the Energy Saving Ordinance or KFW55?

My actual question was, approximately what will be the percentage cost difference if the building is constructed according to KFW instead of the Energy Saving Ordinance.

Just briefly on that. No one here can tell you that for sure, since no one here knows the exact details of your construction project. You would need to know that. And then you would have to be very deep into the subject to determine exactly what your standard lacks compared to KFW55 and what that would ultimately cost. Very few here have that expertise. BUT you have experts at your disposal. Have them review it. In my opinion, your chances are quite good that it could be worthwhile. Wishing you continued success with your project. Regards, Specki

So the next problem is at the door

The loan, as already mentioned, was signed about 3 months ago.
Switching from my already signed but not yet used loan to a KFW loan costs me 35,000 ...
so out of the 90,000 only 55,000 would remain!!

Such crap, how was I supposed to know... I jumped in when the interest rates were at their lowest... so now comes the sh... with the KFW subsidy changes

Better build instead of calculating interest! Every day you wait costs more money than the kfw has to offer. Computer scientists can probably calculate, but you lack the business gene.

My actual question was, approximately how much will the cost difference be in percentage terms if the building is constructed according to KFW rather than the Energy Saving Ordinance.

According to my (university-qualified) math teacher, wanting to insert every numerical example once into formulas is an indication of not having understood them in their function. You can find the principal answer dozens of times in this forum alone (that such subsidies, on balance, in this lot size are only an incentive, but not a bonus). And I repeat my suggestion to think of the object as two finite modules: above is the bungalow with a base slab at just under six meters height, which you should calculate in the KfW variant; between these and the property you insert an income property – specifically here in the "apartment building" variant, where the upgrade calculates differently (namely: it does not), which would look different in the sale as a condominium (but with 5 units above the threshold for WEG self-administration, so forget this). If you choose the KfW variant for the penthouse, this results in a more heavily insulated "base slab" aka upper floor ceiling (and possibly a varied wall construction of the attic). I would not want to reduce the clear room height in the Belle Etage because of this, i.e. plan a whole stair height more from the ground floor to the upper floor. At the latest at this point, I see the possible profit shrink to a marginal amount, but by all means calculate it for yourself.

Switching from my already signed but not yet utilized loan to a KFW loan costs me 35K ...
so out of the 90K only 55K would remain!!

Is that a reliable statement from the bank?
If not, then I would talk to them about what could possibly be done.

L

Is that a reliable statement from the bank? If not, I would talk to them about what could possibly be done.

According to my banker, it is already a gesture of goodwill to be allowed to do this at all... Maybe I can also say that the special repayment should be taken into account. The interest is offset, i.e. for the concluded loan 20 years 1.5% after 10 years payable interest - KFW interest 0.75% = approx. 35,000 € In the already concluded loan there is still an agreement with special repayment, if this is also considered, the amount (35,000) can still change!!