House construction from concrete vs Energy Saving Ordinance 2016

The gentlemen mentioned were / are all representatives of clear architecture, in different eras.

I will only highlight two, since the others would have only illustrated my architectural taste, but were little to not at all active in the style of construction you wished for:

Frank Lloyd Wright (died 1959) is a classic who built almost as frequently as a trademark with very flat hipped roofs. What I wanted to show you from him, I cannot find right now – they were houses with exposed masonry made of large-format stones, I cannot say the material at the moment, they had surfaces resembling volcanic stone.

Mario Botta (born 1943) liked to use small-format concrete stones (2 DF) for exposed masonry.

Similar results could be achieved with Liapor SL in each case.

I do not have image rights to examples, and links are forbidden here by the rules.

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Sandwich-style, inserting insulation between two panels (with a thickness roughly like in prefabricated garages), in my opinion, is not "the real thing". I also do not know of any manufacturer who would be willing to find suitable production methods for that. Every door or window opening is a detail requiring engineer brainpower.

The term "prefabricated parts" is a bit of a stretch here, since these cannot necessarily be standard parts if the house is not to be very restricted in its overall composition. Rather, it is more "pre-fabrication parts" with individual planning and corresponding production in the smallest quantities per identical part (up to an almost regular batch size of "1").

What is possible with a higher degree of standardization you can see from the house manufacturer Dennert Massivhaus.

Actually, your architect is supposed to come up with a solution for this, but for interior and exterior concrete there is no alternative to the sandwich, except for 60 cm ultra lightweight concrete walls. The first is significantly more expensive than a conventional house and the second is much more expensive.

for interior and exterior concrete, however, there is no alternative to sandwich construction, except for 60 cm ultra lightweight concrete walls.

Sandwich is more suitable for multi-family house construction; in batch size "1" the costs for planning each individual panel with its built-ins and openings and the setup costs for the formwork construction are disproportionately high (both absolutely and compared to the material manufacturing costs).

Having to go monolithic with extra thick wall thicknesses simply takes up a lot of floor space for walls. Aside from the fact that it also has optical consequences: with every window you then have the choice between the lesser of two evils regarding what to do with the thick reveal: either make the wall appear thick and visible from the outside, or create "window seats" on the inside (only: do you want those in every room?).

That’s why my alternative suggestion is to switch to "concrete look" on one or both sides instead of "concrete on both sides."

But so far we are still not talking about any specific volume; we only know the desired appearance from the surface.

In addition to the problem of having to meet the requirements of the Energy Saving Ordinance with a monolithic exterior wall/roof construction made of ultra-lightweight concrete, there is the special requirement of finding committed shell constructors for the project with the appropriate experience in formwork construction and the special concrete recipe, as well as a concrete supplier. With a 60 cm exposed concrete wall, a U-value of only 0.5 W/m2K is currently possible. This corresponds to twice the value allowed by the Energy Saving Ordinance of a maximum of 0.24 W/m2K.

Furthermore, the structural engineer must also have experience with the special advantages and disadvantages of lightweight concrete. The material may only be approved in Germany on a case-by-case basis after building inspection. In Austria and Switzerland, it has already been used for a longer period of time. The costs for the entire process, including the costs for permits, processing and formwork tests, etc., are likely to be at least double those of a solid wall/ETICS/plaster or a monolithic aerated concrete wall/plaster, from approx. €480/m2, prices converted from Switzerland. One must be willing and able to afford this.

That’s why my alternative suggestion is to switch from “concrete on both sides” to one- or two-sided “concrete look.”

This concrete look – I still don’t understand how this is supposed to be achieved with Liapor SL stones? It still has to be plastered, right? Or am I seeing it wrong and the stone itself doesn’t really give me a concrete appearance – very annoying that you’re not allowed to link anything here.

Actually, your architect is supposed to come up with a solution for this,

YES, but – but why shouldn’t I inform myself and tell the architect that this or that or the other is our goal – I want to inform myself too about what exists and possibly what could be a solution.

With a 60cm exposed concrete wall, only a U-value of 0.5 W/m2K is currently possible. That corresponds to twice the value according to the Energy Saving Ordinance of max 0.24 W/m2K.

I just had a PDF from Liapor here, where they achieved 0.34 W/m2K with a mixture. But I can already tell... apparently there are just too many drawbacks – so another solution has to be found. Many exposed concrete elements inside and outside?!? I have no idea what options are available here – I’ve looked but if you don’t know exactly what to look for it’s difficult. The term Liapor SL or similar barely gives me good results and if it does, it’s just Liapor stones with plastered facades, so relatively normal :-(

You just have to keep in mind, it must be buildable and the necessary experience must be available, the standard is to make a reinforced concrete shell with exposed concrete on the outside, then insulation on top and ventilated reinforced concrete elements and wooden elements behind. Costs have already been mentioned. For a 160 m2 house, that is about 100,000 just for the walls. If it's worth it to you.