Together with partners, we are investigating the effects of fiber distribution in wood-fiber based insulating materials with the aim of improving thermal insulation. The aim is to reduce the thermal conductivity to less than 35 W/K. The project is funded by the Federal Ministry of Education and Research (BMBF).
Insulation materials made from renewable raw materials are more sustainable and better for the climate than conventional insulation materials such as mineral wool and rigid foams, but they have one disadvantage: their thermal conductivity is in general higher. The distribution and orientation of the cellulose fibers are decisive for thermal insulation. We want to use the directional dependency of thermal transport and arrange differently oriented layers in such a way that the thermal insulation is optimized.
With porosity up to 90 percent, material density and thermal conductivity are proportional. However, this is no longer the case with highly porous materials such as the insulation boards examined; one reason could be thermal radiation, the influence of which has not yet been conclusively investigated.