Researchers at the Fraunhofer Institute for Wood Research, in Braunschweig, Germany have developed a method for creating insulation foam from wood particles.

“Our wood foam can be used in exactly the same way as conventional plastic spray foams, but is an entirely natural product made from sustainable raw materials,” says Professor Volker Thole at Fraunhofer Institute.

The scientists produce the foam by grinding wood very finely until the tiny wood particles become a slimy mass. They then add gas to the suspension, expanding it into a frothy foam that hardens like styrofoam. The hardening process is aided by natural substances such as lignin contained in the wood itself.

Germany is on crash course to improve energy usage, as it weens itself from nuclear power in the wake of the Fukishima reactor disaster. Last fall the German government tightened already stringent energy controls on new construction. The key to meeting the stringent requirements lies in insulating walls and roofs to keep thermal energy escaping unused, say Fraunhofer researchers.

Traditionally the German construction industry uses hardboards or expandable foams based on petrochemical plastics for insulation, but these have negative environmental impacts. So the long-term objective is to replace petroleum based products with materials derived from renewable resources.

For the Fraunhofer wood foam, the grinding method or another chemical process can be used.

“It’s a bit like baking, when the dough rises and becomes firm in the oven,” Professor Thole says. Wood foam is a lightweight base material that can then be made into rigid foam boards and flexible foam mats.

The wood foam solves shortcomings of other wood insulation approaches, such as mats made from wood fibers and wood wool, which tend to shed fibers as they fibrillate and are less stable in shape.

“Over time, the currently used insulation mats made of wood fibers tend to sink in the middle due to temperature fluctuations and damp. This to some extent adversely affects its insulating properties,” says Professor Thole. The wood foam is as good as conventional plastic foams in this regard.

“We analyzed our foam products in accordance with the applicable standards for insulation materials. Results were very promising; our products scored highly in terms of their thermo-insulating and mechanical properties as well as their hygric, or moisture-related, characteristics,” Professor Thole reveals.

Fraunhofer scientists are experimenting with different types of wood to discover which tree species work best, and determining a scheme for mass-producing wood foams on an industrial scale. Wood foam could also provide a long-term alternative to yet oil-based packaging product, expanded polystyrene.