Hello everyone,
I have already read and searched around a bit here, but I am still not quite sure.
We are planning to build a house. It will be a semi-detached house. We have been offered a house with 36.5cm (14 inches) aerated concrete exterior walls without additional insulation. The interior walls are also planned to be made of aerated concrete. Soundproofing boards are to be installed between the wall and the neighboring house.
I have to admit that I am quite a layperson and am slowly working my way through the very conflicting statements and information. We don’t want to build a passive house, but it should be future-proof and reasonably designed. Overall, I would like to aim for a kfw70 house, but that is not solely about insulation...
I have read various information about aerated concrete, clay blocks (Poroton), and also about prefabricated walls. I find it interesting that the U-value of the prefabricated walls is apparently significantly better than that of comparable solid walls (without additional insulation). However, I can’t really grasp what a difference of 0.1 W/(m²K) actually means in reality... I lack the practical understanding of this.
What I think I know:
- Aerated concrete can be installed without additional insulation. But is it any good!? Does it only just meet legal requirements, or is it also sensible to build this way?
- Aerated concrete has poorer sound insulation compared to sand-lime brick or clay blocks. This could be a problem especially for thin interior walls.
- Regardless of what I build (even without extra insulation), a controlled mechanical ventilation system is highly recommended because the houses are very airtight.
- Aerated concrete has poor thermal insulation properties in summer (I still don’t understand why a material supposedly insulates well in one direction – during winter – but not in the other – summer –?!).
- I have often read that the costs of adding extra insulation to a wall do not pay off over a reasonable period (in terms of heating savings – of course this also depends on the heating technology).
Could you help me clarify where I might be wrong? Why is sand-lime brick usually recommended for interior walls instead of aerated concrete? Soundproofing? Less crumbling when drilling? Price?
On the website of the well-known aerated concrete manufacturer, I read that they also achieve low U-values (below 0.2). But these blocks are then less stable, significantly more expensive, and worse in sound insulation... So can you really generalize about aerated concrete or do you need to specify the exact type of block? My supplier only talks about 36.5cm (14 inches) blocks. So I don’t really know which will actually be used... I should probably ask.
Is omitting additional insulation really the “state of the art” and reasonable (does it not pay off in heating costs) or just cheap?
As I said, I don’t want to build a passive house but an economically sensible concept.
Which wall structure would you recommend and why under the above conditions?
Thank you!
I have already read and searched around a bit here, but I am still not quite sure.
We are planning to build a house. It will be a semi-detached house. We have been offered a house with 36.5cm (14 inches) aerated concrete exterior walls without additional insulation. The interior walls are also planned to be made of aerated concrete. Soundproofing boards are to be installed between the wall and the neighboring house.
I have to admit that I am quite a layperson and am slowly working my way through the very conflicting statements and information. We don’t want to build a passive house, but it should be future-proof and reasonably designed. Overall, I would like to aim for a kfw70 house, but that is not solely about insulation...
I have read various information about aerated concrete, clay blocks (Poroton), and also about prefabricated walls. I find it interesting that the U-value of the prefabricated walls is apparently significantly better than that of comparable solid walls (without additional insulation). However, I can’t really grasp what a difference of 0.1 W/(m²K) actually means in reality... I lack the practical understanding of this.
What I think I know:
- Aerated concrete can be installed without additional insulation. But is it any good!? Does it only just meet legal requirements, or is it also sensible to build this way?
- Aerated concrete has poorer sound insulation compared to sand-lime brick or clay blocks. This could be a problem especially for thin interior walls.
- Regardless of what I build (even without extra insulation), a controlled mechanical ventilation system is highly recommended because the houses are very airtight.
- Aerated concrete has poor thermal insulation properties in summer (I still don’t understand why a material supposedly insulates well in one direction – during winter – but not in the other – summer –?!).
- I have often read that the costs of adding extra insulation to a wall do not pay off over a reasonable period (in terms of heating savings – of course this also depends on the heating technology).
Could you help me clarify where I might be wrong? Why is sand-lime brick usually recommended for interior walls instead of aerated concrete? Soundproofing? Less crumbling when drilling? Price?
On the website of the well-known aerated concrete manufacturer, I read that they also achieve low U-values (below 0.2). But these blocks are then less stable, significantly more expensive, and worse in sound insulation... So can you really generalize about aerated concrete or do you need to specify the exact type of block? My supplier only talks about 36.5cm (14 inches) blocks. So I don’t really know which will actually be used... I should probably ask.
Is omitting additional insulation really the “state of the art” and reasonable (does it not pay off in heating costs) or just cheap?
As I said, I don’t want to build a passive house but an economically sensible concept.
Which wall structure would you recommend and why under the above conditions?
Thank you!
Bautraum201522 Jul 2015 21:21It would have been more convenient here, of course (typical woman, right?)... well, alright, I’ll have a little look around then.
H
Hausqualle22 Jul 2015 21:28Bautraum2015 schrieb:
It would have been more convenient here, of course .. yes, sure, but the topic of building physics is so broad and complex that it can’t be answered in just three sentences in a forum ... the entire new energy saving regulation is nonsense anyway, politicians have once again put together something they have no understanding of and have been misled by the construction industryJ
jupartner22 Jul 2015 23:36Hi everyone, good discussion. Okay, there was still the question about the efficiency house 70, I don’t think anyone has addressed that yet:
That is a good target and it can be achieved quite well with 42cm (16.5 inches) walls without additional insulation. This also includes the roof, windows, and basement ceiling/floor slab—everywhere you should aim for U-values between 0.17 and 0.2 W/m²K, with windows having a maximum of 0.9 W/m²K. The heating system should incorporate at least 15% renewable energy. Ultimately, you will need someone to perform an energy savings calculation (according to the energy saving ordinance) for your house to verify the achieved level. This way, you will know exactly which wall thickness and which type of building block are suitable for you. The energy savings calculation is required anyway for the funding application and the building permit/planning permission.
If you apply this year, you can still receive the funding. The KfW recently announced that starting from April 2016, the efficiency house 70 will no longer be an eligible funding standard.
Best regards,
Susanne Junghans
That is a good target and it can be achieved quite well with 42cm (16.5 inches) walls without additional insulation. This also includes the roof, windows, and basement ceiling/floor slab—everywhere you should aim for U-values between 0.17 and 0.2 W/m²K, with windows having a maximum of 0.9 W/m²K. The heating system should incorporate at least 15% renewable energy. Ultimately, you will need someone to perform an energy savings calculation (according to the energy saving ordinance) for your house to verify the achieved level. This way, you will know exactly which wall thickness and which type of building block are suitable for you. The energy savings calculation is required anyway for the funding application and the building permit/planning permission.
If you apply this year, you can still receive the funding. The KfW recently announced that starting from April 2016, the efficiency house 70 will no longer be an eligible funding standard.
Best regards,
Susanne Junghans
B
Bauexperte23 Jul 2015 10:06Hausqualle schrieb:
It is not recommended to use aerated concrete (porous concrete) for interior partition walls; instead, calcium silicate brick should be used. No reputable building inspector would even consider that.
Regards, Bauexperte
B
Bauexperte23 Jul 2015 10:16Hello,
What a moody response for a forum – with that attitude, you might as well not bother writing even a single sentence!
By the way – the field "Learned / Practiced Professions" is mandatory when registering; even as an assumed "retiree," you have surely learned or practiced a profession at some point. Knowing this helps users who ask or read to better assess your answers. Please complete it!
Regards, Bauexperte
Hausqualle schrieb:
.. .. sorry .. but then I would have to copy entire books ... .. but if you searched around on the internet, you would find plenty of literature ... have fun ..
What a moody response for a forum – with that attitude, you might as well not bother writing even a single sentence!
By the way – the field "Learned / Practiced Professions" is mandatory when registering; even as an assumed "retiree," you have surely learned or practiced a profession at some point. Knowing this helps users who ask or read to better assess your answers. Please complete it!
Regards, Bauexperte
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