Is it worth paying the extra cost for KFW55 or not?

Our ground is very rocky though. Could become a huge cost trap.

Just get a quote. Then the "trap" is gone. Besides, in this country, anyone who usually drills 80-100m deep will sooner or later hit bedrock. Don’t confuse that with the effort of digging a pit for a basement using an excavator (!).

It's about digging For the [Erdkollektoren]. [Erdwärmesonden] are already discouraged in the development plan because of swelling rock, unfortunately

The trench collector is also often 1.8 meters deep. So the type of soil is quite important.

Hello, air-to-water heat pumps are power guzzlers, the promised consumption values are absolutely unrealistic, unless you don't want more than 19 degrees room temperature. For the extra cost, you can heat for a long time. For controlled ventilation, I can only advise you that decentralized ventilation systems are just an emergency solution.

Are you digging up every old thread now to show your aversion to air-water heat pumps? It’s getting annoying.

My combination will be a KFW 55 house with an air-water heat pump, a photovoltaic system without storage, and a fireplace – and I’m looking forward to it.

Then look forward to the electricity costs