ᐅ Is it feasible to achieve a KfW 70 energy efficiency standard using exterior masonry with 17.5 cm autoclaved aerated concrete (AAC) blocks, 16 cm mineral wool insulation, and a brick veneer?
Created on: 16 Feb 2015 18:17
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derstefanm
Hello everyone,
I couldn’t find any useful information online, so I have a question.
Is it possible to meet the KfW standard with a new build wall construction consisting of 17.5 cm (7 inches) sand-lime brick / 16 cm (6 inches) glass wool / 4 cm (1.5 inches) air gap and facing brick? I know that for KfW 70 not only the wall structure matters but also the energy source, windows, etc. However, in principle, would this be feasible? I am looking for an alternative to Poroton, and sand-lime brick seems like a good option, especially considering sound insulation and fastening possibilities.
Thanks for your answers.
Best regards,
Stefan
I couldn’t find any useful information online, so I have a question.
Is it possible to meet the KfW standard with a new build wall construction consisting of 17.5 cm (7 inches) sand-lime brick / 16 cm (6 inches) glass wool / 4 cm (1.5 inches) air gap and facing brick? I know that for KfW 70 not only the wall structure matters but also the energy source, windows, etc. However, in principle, would this be feasible? I am looking for an alternative to Poroton, and sand-lime brick seems like a good option, especially considering sound insulation and fastening possibilities.
Thanks for your answers.
Best regards,
Stefan
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Sebastian7922 Feb 2015 10:14It is possible if you have a suitable heat source. However, the ground slab should or must be properly insulated as well.
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Sebastian7922 Feb 2015 10:23HT is also independent of the technology (at least I'm quite sure about that).
We calculated a HT of 0.3, which is not very impressive, but it will still change.
Still, we have effectively reached KfW 56.
We calculated a HT of 0.3, which is not very impressive, but it will still change.
Still, we have effectively reached KfW 56.
0.3 W/(K·m²)? The construction described here has 0.2 W/(K·m²) – with aerated concrete it would be 0.15 W/(K·m²), so about 25% better. According to Wikipedia, this corresponds to 70% of the maximum allowed value in the 2009 Energy Saving Ordinance, which was 0.24 W/(K·m²) – so theoretically 0.168 W/(K·m²) would be sufficient for KfW 55 standard... if it were really that simple 😀 Of course, other external walls and windows have to be taken into account as well.