KfW55 EE house with 42.5 Poroton: planned too tight?

It can't be due to Poroton. We build with 36.5 cm Poroton and KfW 55 is not a problem. It will probably be due to the windows. We have passive house windows.

Such statements are simply answered much too superficially. What applies to you does not necessarily have to fit for the other construction project. The entire building envelope must be considered with regard to transmission heat losses. So if a comparison is to be made here, significantly more information must be on the table.

Such statements are simply answered far too superficially. What applies to you does not necessarily have to fit with the other construction project. The entire outer shell must be considered with regard to transmission heat losses. So if a comparison is to be made here, significantly more information must be on the table.

It probably says and not certainly. And if the bricks are the same only thicker, it is HIGHLY LIKELY that it will not be because of the bricks.

I also wonder why it is so tight for us. I will call the energy consultant and ask what values he calculated with and where the weak point might be. Could it be that perhaps the floor slab is not insulated?

Please refrain from making a blanket assessment of individual components regarding the thermal insulation calculation. Your floor slab is only one piece of the puzzle, and not the optimal approach. The floor slab only plays a minor role in the overall calculation, since the DeltaT between the house and the ground is lower than with the walls, windows, or ceiling.

Please stop the general consideration of individual items regarding the thermal insulation calculation. Your floor slab is only one mosaic piece, and not the optimal approach. The floor slab only contributes to a small extent to the overall calculation, since the DeltaT between the house and the ground is smaller than for the walls, windows, or ceiling.

Do I understand correctly that the four most important mosaic pieces are: walls, windows, floor (slab), and the insulation "upwards"?

Can’t these then be compared to each other?

Maybe I have too many windows :rolleyes:

My concern: if another energy consultant calculates this, they might come to the conclusion that KfW55 is not met. Question: Would you build it like this? Or is the risk too great that the house will be slightly worse in the final acceptance than on paper,

Where is the problem? If the house is built as planned, the issue is settled. Whoever wants can calculate it. This is all completely stress-free. In the end, the energy consultant who made the calculation confirms that we built according to his specifications. Nothing is recalculated. 2x2=4 will not suddenly become 3.98. The whole discussion is totally unnecessary.