The invention refers to thermal insulation materials. A wall panel made of an environmentally friendly, porous biofibre material providing thermal insulation, moisture resistance and high fire resistance is provided. The panel comprises a dense, mechanically durable and fire resistant outer layer and a less dense, thermally insulating inner layer. A method for production of the wall panel from layers of different density is provided as well. Said layers are moulded in a pre-prepared mould, wherein the density of layers is adjusted by pressure and the amount of binder added.