Floor construction new build single-family house kfW55

You already mentioned the stones you build with in another thread (I hope I’m not confusing you now). The stone mentioned there has a U-value of 0.21 W/(m² K) and would therefore at least according to the reference value method for KFW 55 determination not be suitable. Now you write here the U-value of your floor slab, which according to the mentioned method is an exact bullseye. And even too good, as you say. I wonder which components of your house have the U-values that tip the balance the other way. That leaves only the roof and windows, with the latter being a nasty cost block if you overdo it. Front door left aside. I’m really interested because we also need to deal more intensively with the topic right now. It would be great if you could briefly list your values.

You’re not confusing me, I’m the one with the 0.08 bricks.

As we know, meeting the KFW55 standard is all a mixed calculation of primary energy, energy efficiency and building material. Without controlled residential ventilation, we probably would have needed additional extras in terms of materials. Thanks to the controlled residential ventilation, we meet the minimum requirements relatively easily in my opinion, and that was the reason why we went for KFW55.

Since the energy calculation is a nice big chunk, I hope I got the right values. Here are what I consider the most important U-values:
Windows Ug 0.5 Uw 0.8
Roof 0.17
Exterior walls 0.21
Basement walls plinth area 0.26
Basement walls earth-contact 0.29
Floor slab/basement floor 0.25

Air/water heat pump (COP 3.7) with 95% share, 5% electric (auxiliary heating) as well as controlled residential ventilation with 90% heat recovery. Calculated annual heating energy demand 3582 kWh.