Oh, I assumed that KfW55 is more or less the "standard" among construction companies anyway and that you can hardly get anything cheaper...
We are building according to the Building Energy Act and are also getting it cheaper from our prefabricated house manufacturer. Our motivation to build without subsidies was, among other things, that we did not want some of the requirements (heat pump, mechanical ventilation, ...) and also did not want to deal with an energy consultant without experience. Acquiring experience has not succeeded for us, among other reasons, due to lack of motivation.
What we will certainly do, when cheaper storage systems become available, is switch to photovoltaics and buy a wallbox and an electric car. We are already very much looking forward to that. But we will probably do that without subsidies too, too much bureaucracy.