Which type of controlled residential ventilation are we?

The difference lies in the "K"

The K ensures a significantly higher exchange with the outside air than [Falzlüfter] could ever achieve. That is why there is also the increase in comfort. But in the end, it makes the house significantly less airtight.

Yes, you have understood it, one ensures air exchange and the other are just holes in windows (with all the consequences)
[B][/B]
P.S. The thing with the leakiness is not really true... you are misinformed about that...
[B][/B]
[B]Proof of the airtightness of the entire building

If an inspection of the requirements according to § 5 Abs. 1 is carried out, the volume flow rate measured according to DIN EN 13829: 2001-02 at a pressure difference between inside and outside of 50 Pa – based on the heated air volume – for buildings
- without mechanical ventilation systems 3 h-1 and
- with mechanical ventilation systems 1.5 h-1
must not be exceeded.[/B]

Is a review of the requirements according to § 5 Abs. 1

isn't that only necessary if you are dependent on the "KFW drip"?

With or without KfW... this is just meant to illustrate how houses are built nowadays... the general contractors and whatever you want to call the construction companies all build according to their standard projects with more or less small deviations... especially with prefabricated houses... (I do not mean the floor plans etc., but the overall concepts of the houses)