Hello.
We are planning a single-family house together with an architect, aiming for KfW55 standard. According to the architect, using 36.5 cm (14.4 inches) bricks should not be a problem. With these dimensions, everything is now also approved for the building permit / planning permission.
The structural engineer is now skeptical, and the energy consultant said this wouldn’t be possible at all.
So basically the question is: Has anyone successfully done this before?
Also to be installed: air-to-water heat pump, controlled ventilation with heat recovery.
Thank you.
We are planning a single-family house together with an architect, aiming for KfW55 standard. According to the architect, using 36.5 cm (14.4 inches) bricks should not be a problem. With these dimensions, everything is now also approved for the building permit / planning permission.
The structural engineer is now skeptical, and the energy consultant said this wouldn’t be possible at all.
So basically the question is: Has anyone successfully done this before?
Also to be installed: air-to-water heat pump, controlled ventilation with heat recovery.
Thank you.
We are currently planning a KfW 55 house. It will be built monolithically using 36.5cm (14.5 inches) aerated concrete (PPW2 specified). There will also be insulation under the slab and on the ceiling, along with an air source heat pump. I hope everything will be approved as planned. However, the general contractor has had all thermal bridges professionally certified (detailed proof), which means there is a smaller blanket deduction in the thermal bridge calculation. According to them, this should make meeting the KfW 55 standard achievable, which I really hope, as our KfW loan depends on it.
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DragonyxXL15 Jul 2016 09:07jaeger schrieb:
If it’s that extreme, then 42.5 probably wouldn’t have helped either, right? Or could you have avoided KfW55 and just didn’t want to? No, the 42.5 alone wouldn’t have been enough. It might have worked with 42.5 at a thermal conductivity (λ) of 0.07 and a detailed thermal bridge calculation. But you have to keep in mind that the 42.5 material already costs about 15% more, and the 0.07 material costs another 65% more than the 0.09 one. With our approximately 215m² (2316 sq ft) of exterior wall, that’s a significant additional cost. I estimated that the thermal bridge calculation would add around €8,000–12,000. For us, the monolithic wall construction just isn’t worth that expense.
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daniels8715 Jul 2016 11:11It's amazing how much the costs can vary. We pay about €1500 for the more extensive construction supervision and around €800 for the additional insulation. As I mentioned, with 36.5cm (14 inches) thick bricks having a thermal conductivity of 0.09 W/(m·K). Could this be due to the less favorable surface-to-volume ratio of a bungalow?
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DragonyxXL15 Jul 2016 11:18daniels87 schrieb:
Is it due to the lower surface-to-volume ratio of a bungalow? That definitely makes a big difference, yes. However, our floor plan also complicates things.
The ideal solution is, of course, a north/south orientation. We only have southeast/northwest, though.
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