Heating system: KFW subsidy 151. Is an energy consultant mandatory?

What is promoted is what serves the energy renovation of individual measures (or complete package). That is what your energy consultant tells you.

For what term does the bank offer this interest rate? To me, it sounds like a 10-year condition. A comparable purchase interest rate is currently at 1.40 %, which means the margin is somewhere between 0.23 - 0.40 %

The purchase interest rate for KFW loans is exactly at 0.3725 %

Correct, for 10 years. Sounds like no big margin to me... especially since many banks just gawked and congratulated us on the good interest rate because they couldn't keep up.

Thank you for the support!