In this research, we could achieve a new route through introducing an insulating material with lower thermal conductivity and lower cost. The polyurethane foam and rice straw composite proved to have a higher efficiency than the pure polyurethane foam through the insulation properties, mechanical properties and the overall cost. The thermal conductivity of this new composite is 12% lower than that of the polyurethane foam with thickness reduction of also 12%. The advantage of this sample is also using a waste such as rice straw which is easily available for free. Rice straw is a good selection as a filler due to its low thermal conductivity which improves the material insulating properties. Consequently, this results in reducing the cost of insulation by 28.35%