ᐅ Is KfW 40 achievable with 36.5 cm Poroton bricks?

Hello everyone!
I am wondering if it is generally possible to build a KfW 40 house using 36.5cm (14.4 inches) Poroton blocks, assuming that all other requirements are met.

Thanks in advance.

Regards

I can only speak from my own experience. The basement already had better values than the exterior wall. Definitely not with a T8 insulation; its lambda value is only about 0.21. As far as I recall, the requirement for KfW 40 is around 0.175.

Windows had a value around 0.85. I believe windows can reach a maximum of 0.76 or 0.72, which would already meet Passive House standards. The front door was 0.91, and so on. In the end, all values were better than required except for the exterior walls. There, it was just on the edge.

That’s why only KfW 55 was achieved.

Poroton filled with perlite / insulation wool / wood or only with air chambers?

Nicon1001 schrieb:

I am wondering if it is basically possible to build a KfW 40 house using 36.5cm (14.4 inches) Poroton blocks.

I haven’t gone through your other thread—where you still mentioned KfW 55—to see if this has already been mentioned, but if you read around here a bit, you will regularly come across the suggestion that KfW 40 is in most cases a bit of a pipe dream.

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annab377 schrieb:


Poroton filled with perlite / insulation wool / wood or just with air chambers?

That would not matter in the first place.

As far as I know, this is not possible without additional insulation.
If you want to build without extra insulation, you generally need a 49.5cm (19.5 inches) wall thickness. If I’m not mistaken, there are now also a few 42.5cm (16.7 inches) blocks that can meet the KfW 40 standard. However, there are only one or two types of these blocks. They are also filled with mineral wool or something similar.
But as far as I know, the 36.5cm (14.4 inches) blocks definitely do not meet the standard.