The purpose of the investigation was to study insulation properties of different fibre shaped natural materials. For study celluloze flakes and hemp was used, which are the most effective natural materials. Hemp was divided in to long fibres, grind fibers and wood-like core fibre. We investigated differences between type of material, board densities and their impact on coefficient of thermal conductivity. For investigating the differences in insulation properties, we expose materials to different climat conditions. Influence of resin share and different additives on insulation properties was also investigated. We determined the differences in insulation properties related to type of material used. With the exeption of long fibres, the materials with the higher density had higher thermal conductivity. We also found out, that the materials with the higher density had greater effect on thermal conductivity when exposed to high moisture environment. Thermal conductivity increased with increasing resin share. The change of color was noticed at the silica gel, when the climat conditions changed. That means that it is good for monitoring the change of moisture in insulation.