Energy consultant recommends KFW 55 - Recommended with solid construction?

I believe you are very convinced of your gas, to each their own. I just think it is not right to condemn all energy sources that are not based on fossil fuels as per se uneconomical, impractical, and only existing due to nicely calculated values.

Achieving a KFW-something-standard through incredibly thick thermal insulation always sounds great, but it's not such a big art.

It remains as it always is, every Jeck is different and everyone should live with what they like.

@ construction expert .....do you remember the thread where it was about heating half the basement? And where suddenly the general contractor wanted to heat everything and wanted to push the extra cost on me? I had calculations made by his structural engineer. It turned out that he included the attic even though it is a cold zone. Likewise, the entire basement was included even though it was planned to be half cold and half warm. Now much more insulation is required to achieve KFW 55, and the general contractor wants to push that on me again.

Good evening,

@ Bauexperte .....can you remember the thread about heating half a basement?

Yes; I am still waiting for the resolution. Didn’t you want to consult an expert?

And then suddenly the general contractor wanted to heat everything and charge me the extra cost? I had the calculations done by his structural engineer. It turned out that he included the attic even though it is a cold zone. Also, the entire basement was included even though half was planned as cold and half warm. Now much more insulation is required to achieve KFW 55, which the general contractor wants to impose on me again.

If I remember correctly, I wrote it was “nonsense” concerning the partial heating of a basement via underfloor heating. The basement belongs inside the insulated envelope; after all, the insulation was contractually owed? Likewise the KfW 55 status?

I really don’t think a structural engineer would calculate incorrectly on purpose. Mistakes, however, can/may also happen to him.

Rhenish greetings from the road

Hello construction expert.
Yes, insulation and KFW 55 are contractually owed. Partial heating was planned in the building contract AND in the approval plan.
Nevertheless, the structural engineer calculated the entire basement and additionally the entire attic.
This structural engineer - economically independent of the general contractor but additionally to be commissioned by the client as a KFW verification authorized company - recommended by the general contractor.
Almost always the client decides on this one because he also created the statics for the general contractor. Who cares if the calculations are right or wrong? (The main thing is KFW 55 on paper)
I do care!
Only when I involved an external KFW-listed expert to check the thermal protection verification and to prepare the application, it was noticed that the calculated volume did not match my planned building (partial heating of the basement and closure of the thermal envelope at the upper floor ceiling).
Now some components have to be additionally insulated. Proof of:
• Avoidance of thermal bridges ΔUWB ≤ 0.035 W/(m² K) (thermal bridge verification: calculation report by the general contractor)
As a basis for the KFW, the alternative verification of a KfW Efficiency House 55 according to reference values – see page 2 ff (kfw technical leaflet).
I do not want to blame the structural engineer, but I have heard from some KFW experts that the general contractors try to trick.