Technical Abstract: The use of cellulosic fibers, such as cotton, kenaf, ramie, jute, flax, and bagasse, in the manufacturing of nonwoven composites for a variety of automotive parts, such as headliners, wall panels, and trunk liners, could significantly enhance their “end of life” biodegradability and also improve their thermal insulation properties. Currently, automotive nonwovens are made from synthetic, petro-based polymer materials that are not biodegradable, thus creating significant environmental problems. Three different sets of “sandwich-type” nonwoven materials were manufactured by layering cellulosic webs, with recycled thermoplastic synthetic fibers and/or using readily biodegradable binders such as polyvinyl alcohol and Eastar Biocopolymer. A steady state heat flow meter was used for evaluation of the thermal insulation properties of these biodegradable, low cost nonwoven composites. The results show that the thermal insulation properties of cellulosic-based nonwoven composite materials vary significantly, depending on the type of the vegetable fibers, ratios of cellulosic to synthetic fibers, nature and quantity of the binder, design, and the resulting bulk density of composites.