How do I achieve the "EE" in Kfw 55?

simply just air-to-water heat pump + controlled residential ventilation in the heat pump center from Wolf.

Why is a controlled residential ventilation necessary to achieve "EE"? Would the air-to-water heat pump alone also be sufficient?

What is a controlled residential ventilation system needed for to achieve "EE"? Would the air-water heat pump alone be sufficient?

Air-water heat pump would also be sufficient on its own

The controlled residential ventilation has nothing to do with the EE. However, the controlled residential ventilation can be necessary to comply with or fall below the heat losses. We build without controlled residential ventilation and only with the heat pump.

To avoid opening an extra thread.

Does anyone know how it works with the bungalow with concrete ceiling & KFW 55ee? Do you have to insulate the concrete floor in the attic, or can you insulate the roof instead (and leave a raw concrete floor)?

We would like to have a staircase installed immediately and only convert the attic later. Would a small hallway upstairs be sufficient? Or has anyone solved it differently?