Calculate/estimate the "KfW value" yourself

Hello,

our building company sells us the house as a KFW70.

Planned is a 40 cm wall structure (24 cm concrete block + 16 cm ETICS WLG032) (0.18 W/m²K) 20 cm roof insulation (upper floor ceiling or flat roof) (0.18 W/m²K) 13 cm insulation between the floor slab and screed (0.25 W/m²K) Windows Uf 0.93 Air/water heat pump Central controlled residential ventilation with heat recovery

Since I am considering possibly better windows (80 instead of 70 profiles) as well as more insulation in the roof (0.18 => 0.11) and under the floor slab (0.25 => 0.18), I would be very interested to know where we currently stand.

Is it just barely 70 or maybe already 60? How much more would need to be done to reach 55? Would it possibly require a small photovoltaic system or solar hot water?

Are there any online tools where you can calculate this yourself? Or (free) software? I have all the U-values etc. I have also already done a heat demand calculation with the U-value calculator.

What KFW 55 brings in pure funding can be easily calculated: 2500€ repayment subsidy + 1125€ (0.25% interest advantage for 10 years, with bullet loan) = 3625€

Our calculation was made with the Ziegel Energieeinsparverordnung software. There is a student version available for free download, but I don't know if its functions correspond to the paid version, though you can adjust a lot of settings. You can take a look, but the calculation is not done in just a few clicks; it is somewhat more complex.

And you have swept the more expensive proofs plus more intensive construction supervision under the rug - it is not simply done with a bit more insulation.

Especially since you now have a standard value for thermal bridges, with KFW55 they are explicitly calculated...

The repayment grant is definitely gone for that...

After I entered the data, the dream is over anyway, unless I made a gross mistake