ᐅ KfW 40 or better in solid construction without additional insulation possible?

Created on: 18 Nov 2019 08:44
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Specki
Hello,

I was initially set on a timber frame construction for my future house. However, I am now reconsidering solid construction because it does have its advantages. Ideally, I would prefer this without additional external insulation, as that would be redundant and insulation typically does not last as long as the masonry itself. Poroton seems the most appealing option to me at first glance.

But is that even feasible? Are there bricks (or other solid building blocks) that on their own meet the KfW 40 standard, or possibly perform even better?

Does anyone have experience with this? Has anyone actually built something like this?

I’m open to discussion if you believe additional insulation makes sense. However, no “Styrofoam” will be used on the exterior walls; if anything, it will be an alternative material.

The comments I would rather avoid are those suggesting a lower energy standard would be sufficient. I will not build anything below KfW 40.

Thanks in advance for your input.

Best regards,
Specki
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apokolok
18 Nov 2019 12:53
It still doesn't pay off even after 60 years...
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Specki
18 Nov 2019 12:59
I don’t quite believe that, although I’m not deeply familiar with the topic yet to be able to prove it to you. If you had said 20 years, I probably would have agreed with you. And even then: The environment/nature will thank you.
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Lumpi_LE
18 Nov 2019 13:04
apokalok is right, saving from KfW 55 to 40 might save you around 50, let’s say 100€ per year. So it’s never really cost-effective.
There are other reasons to build a well-insulated house, and there is nothing wrong with building a Passive House or KfW 40 or 40+ house. Just expecting to save money by doing so should be quickly dismissed.
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Specki
18 Nov 2019 13:07
I never said anywhere that I necessarily want to save money with this.

Of course, I do care about keeping the initial investment costs as low as possible. But it’s not the only factor.
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Lumpi_LE
18 Nov 2019 13:14
Specki schrieb:

I never said anywhere that I definitely want to save money with it

Of course, you just said that you want to build to KfW40 standards because of lower heating costs...

Now suddenly you're talking about minimizing initial investment costs, which completely contradicts KfW40/passive house standards. You should probably take some time to clarify what your actual goals are.
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Specki
18 Nov 2019 13:25
Yes, Lumpi, you’re right.
Low heating costs over the next 60 years. I hope to live in the house for that long. And then maybe it will be for children or others as well.
I’ve kind of equated low heating costs with lower energy consumption, which basically benefits the environment.

I’m not exactly sure what I’m committing to yet. I probably won’t know until we move toward detailed planning.
For example, whether an extra 5,000€ translates into an estimated monthly saving of 10€ is something I can’t finalize right now.

My main question is whether it’s even possible to reach such a low energy standard with solid construction without additional insulation, and if that would make sense at all.
Obviously, it doesn’t!

So the next thought is:
Solid construction with a ventilated façade or timber frame.
Now the challenge is to weigh the pros and cons and roughly compare the costs at this stage.

As I said, I can’t define my position regarding insulation thickness and investment costs yet, as there are still too many variables involved.
Once the general framework (construction method, etc.) is set, I can start to calculate how much additional investment I consider reasonable in relation to future savings.

I hope this makes things a bit clearer now.

Regards,
Specki