More and more home owners are insulating the walls and ceilings of their houses to save on heating costs and reduce carbon dioxide emissions. However, their commitment to environmental friendliness usually stops short at the choice of insulating materials.
Fiberglass and rock wool along with plastic foams made from polystyrene or polyurethane are still the first choice for many. Only around 5 percent of insulating materials are produced from renewable raw materials such as reed, flax, hemp, straw or wool. However, insulating blankets made from natural materials have definite advantages: their production requires relatively little energy, they are not harmful to health and, when they are no longer needed, they can be disposed of by composting or carbon-neutral incineration.
Together with four partners, the Fraunhofer Institute for Chemical Technology ICT in Pfinztal has developed new bio-based materials, including one based on hemp – a plant which is native to Germany. Conventional insulating materials made from hemp contain polyester supporting fibers to hold the plant fibers together. Now, however, a biopolymer extracted from corn fulfills this function. The new insulating material is thus made entirely of natural products and is completely biodegradable – and, most importantly, it works, as tests have shown.
“Its insulating characteristics come very close to those of conventional products,” explains ICT project coordinator Darius Primus. It is light, has low heat conductivity and, thanks to a soda bath, fulfills fire safety regulations. On top of that, it easily absorbs and releases moisture, helping to prevent damage to the building. The only disadvantage is that the supporting biopolymer, which amounts to about 10 percent of the insulating material, currently still costs twice as much as polyester.
ICT researcher Dr. Axel Kauffmann has taken a different approach. In a project supported by the Landesstiftung Baden-Württemberg (a foundation for the funding of projects of benefit to the public), he investigated the suitability of a variety of biopolymers for insulating panels, in order to find environmentally friendly alternatives to polystyrene. His work has shown that this approach is viable. The new bio-based material has similar characteristics to polystyrene and can therefore be used as an insulator. However, it is also two or three times as expensive at present. Nevertheless, Dr. Kauffmann hopes that the price of biopolymers will fall as production levels rise.
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