Thermal comfort property is closely related to the concept of thermal insulation and includes protection against heat. This research paper presents an experimental study on thermal insulation properties, for natural fiber composite materials: a natural fiber (Coir/Jute) with different blend proportions of raw materials mixed with rigid polyurethane foam as a binder. The natural fiber composite materials were characterized by both thermal resistance (Thermal Insulation Value TIV) and also in terms of heat transfer (thermal conductivity). Thermal insulation values were measured according to Lee’s disk method (ASTM C177). The influence of the structure of these materials on the thermal insulating properties was analyzed. The experimental results show the thermal resistance performances of natural fiber composites based on coir/jute fiber materials, thus promoting environmentally friendly solutions.