press information

14-Nov-2017 | 762-EN

Sustainable building using sheep's wool insulation

In an exploratory project, an environmentally-friendly process has been developed for treating sheep's wool to protect it from moth damage without using insecticides. The aim of the project, sponsored by the BMBF, was to make usable eco-friendly insulating materials that meet the requirements for sustainable building.

Boennigheim (ab) It is not only conventional insulating materials that offer very good insulating properties and can significantly reduce heating costs, but also natural sheep's wool fibres. Their high bulk density also makes for excellent sound insulation. Furthermore, sheep's wool is very long-lasting, not readily flammable and it binds harmful substances from the air. Overall, there are considerable health and environmental benefits to using sheep's wool insulation, because the method poses no risk to either producers or users. The only disadvantage of insulating mats based on sheep's wool is that they are frequently infested with clothes moths (Tineola bisselliella). The problem makes treating them with chemicals virtually unavoidable.

Chemical-free insulation?

In the light of the beneficial properties of sheep's wool, the aim of the project - part of the "New products for the bioeconomy" funding scheme - was to develop an environmentally-friendly process for treating sheep's wool which would protect it from moth damage without the use of insecticides.

The proposed solution was based on plant tannins that are already used in the production of leather, so-called secondary metabolites which plants use to protect themselves from pest infestation.

The idea was to use the tanning process to develop a biogenic treatment process for virgin wool, which would lead to new and eco-friendly processes for the textile industry (including for felts and technical textiles).

The research work began by producing tan solutions from tanning agents such as the bark, fruit and leaves of various plants. Then a suitable tanning process for sheep's wool was developed and the technological tanning formula was optimised specifically for moth resistance. Various parameters were studied which had an effect on the tanning process. A clothes moth breeding operation was set up and clothes moth testing was carried out in accordance with DIN EN ISO 3998 to verify whether the objective of moth resistance in woollen textiles had been achieved.

When mechanically compacted woollen felt was tanned using crushed plant components (containing tannins), the resistance of the treated material to moth damage was considerably improved. The resistance to clothes moth larvae that was achieved was much higher than that of untreated sheep's wool. Commercial treatments containing permethrin (based on insecticides) which were used as a positive control in the established moth test procedure proved to be only slightly more resistant.

A warm and woolly prospect for sustainable building

This shows that tanning technology can be used to produce an "ecological insulating material" from sheep's wool that does not use synthetic insecticides. The ecological assessment produced during the project, in cooperation with the IFEU Institute (Institut für Energie- und Umweltforschung Heidelberg), shows clear benefits in terms of ecological potential, compared with conventional insulating materials. Using only biogenic raw materials means that bioeconomical aspects have been taken into account, while, at the same time, undesirable environmental effects are avoided. This therefore represents an important contribution to sustainable building.

The Hohenstein Group would like to take this opportunity to express its thanks once again for the support it has received from the project sponsor Jülich │ Forschungszentrum Jülich GmbH and to the Federal Ministry for Education and Research and our partner BioPro Baden-Württemberg for their assistance with this project.

Additional information:

Renewable raw materials based on plant and animal fibres are once again increasingly being used as insulating materials. In an overview of the market, the brochure "Insulating materials from renewable raw materials" describes numerous ways in which these insulating materials can be used and underlines the advantages of choosing and using natural insulating materials such as sheep's wool, wood fibre, flax, hemp etc.

When existing old buildings are being converted, and there is a need to avoid structural damage, these insulating materials are known to have structural advantages in the context of change of use or modernisation work.

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