Is starting construction in 2015 reasonable?

I think you have already given the best argument yourself ... if you want to meet Kfw70 according to the Energy Saving Ordinance 2014 anyway, it doesn't make much difference to build "only" according to the Energy Saving Ordinance 2016 next year. Additional costs due to rising construction prices and without an extra KfW loan probably weigh a bit more. The currently falling interest rate for a long-term financing as we plan, for example, brings significantly more savings. If we had built in August 2014, we would have paid a total of 30,000 EUR more in interest than today with a term of 25 years.

Is there actually a set period within which you have to start building after the building application has been submitted? Or after a permit has been granted?

To my knowledge: valid for 1 year, after that you have to submit it again, but you can be pretty sure that it will be approved again, unless something significant has changed (e.g. a development freeze, new zoning plan, etc.)

Hello,

To my knowledge: valid for 1 year, afterwards you have to apply for it again, but you can be pretty sure it will be approved again, unless something has changed significantly (e.g. a development freeze, new zoning plan, etc.)

This varies by state. In NRW, for example, it is now between 2 and 3 years, depending on the municipality.

Rhenish greetings

The currently falling interest rate for a long-term financing, as we plan for example, brings significantly more savings. If we had built in August 2014, we would have paid a total of 30,000 EUR more in interest than today for a term of 25 years.

Exactly. Interest rates keep falling and the resulting interest savings are significantly higher than the 25% of construction costs mentioned here, for example.

Wait a little longer and it will become cheaper overall.

That interest rates will go down even further, I really cannot believe...

I really can't believe that interest rates will go down even further...

Many people haven't been able to believe that for 10 years.