Foto: Frontansicht des Bürohauses Tattendorf

Optimisation of ecological construction components for industrial serial production of precast elements

The project focused on passive house elements from straw and clay. Special interest was paid at a novel straw insulation as well as at an efficient drying process of the clay. Sustainability of the building materials was a very important aspect within the project.

Short Description




Starting point/Motivation

Along the HdZ (House Of The Future) R&D projects "Bauteilentwicklung" and "Demonstrationsbau Lehm-Passivhaus Tattendorf" a high efficient ecological construction system was developed successfully up to advanced state of prototype.

LOPAS AG planned to implement this construction system by building an industrial production environment at Dobersberg in Austria.

Regarding sustainability (climate protection, efficient use of resources, production without waste) clay and straw are ideal building materials and being practically renewable raw materials and are available in huge dimensions locally. Combining the heavy mineral building material clay (Biofaserlehm / Biofibre-Clay) with modern wood frame constructions and insulation from straw is optimal. It is shown as results of the monitoring project of AEE-INTEC.

However the combination of these three building materials, which are sustainable and in large quantities available cannot be integrated in current industrial production processes for prefabricated houses in a cost efficient way. On the one hand there is a need for development and optimization of new and modified manufacturing technologies adjusted to the characteristics of the materials and on the other hand there is a need for adjusted construction components. The present-day available manufacturing technology is fully optimized for the use of (predominantly gypsum material) panel-sized building materials.

The ecological food print as a standard of comparison measured by figures of OI3 life cycle analysis.

The demonstration project "LPH (Clay-Passive House) Tattendorf" has shown that ecological food print is six times smaller than a conventional solid construction at the same level of heating performance. Surprisingly the food print of the building technique used in Tattendorf was even less than half in size by eco balance figures (OI3) compared to second ranked ecological demonstration project. Even though it was a similar ecological building project.

Thesis on sustainability:

Passive house concepts cannot be called "sustainable" and "climate-neutral" till then "grey energy" of construction materials is reduced like in the present ecological building concept.


The implemented project has met its objectives by far in development of construction materials and in compounding of components for industrial workability. The conceptual planning of a whole industrial production process could not be finished. For straw as a raw material a way of processing was developed which can be done at the site of the local supplier (local farmer). The farmers process the straw to the desired chipped size and after removing dust deliver it to the plant where it is manipulated into the space between horizontal and vertical members of the timber frame construction as insulating infill of the prefabricated wall and ceiling elements. The originally expected technology of manipulating straw could not be realized because the technology of processing the chipped straw had to be changed due to unanticipated variances in thermal conductivity behavior.

In this range there were some surprises at the intermediary results. Additional steps of tests had to be integrated into the project. The realized calculated value of thermal conductivity of the insulation with chipped straw of 0,042W/m2K was gratifying. The processing plant based on these results will be prepared in a following R&D project which aims industrial production in the factory site. The development of the clay coating process was successfully finished until to the state of planning the production process. To realize the results of clay coating production process for the insulation with straw has to be finalized. With the existing result of research a partially atomized production process is feasible and partly realized. Partial results were integrated into current manual production and were proved on suitability in everyday production.

Proposals for improvements reflected by practical experience were integrated into current R&D activity.

Project Partners

Project management

Herbert Kirl, MBA
Roland Meingast

Contact Address

Oberwaltersdorfer Straße 2c
A 2523 Tattendorf
Tel.: +43 (2253) 81031
Fax: +43 (2253) 81031 - 18

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