This paper deals with a brand new cost-effective, ecological and energy-efficient insulation material application based on Miscanthus x Giganteus with a reduced cement binder amount enriched with a smaller quantity of zeolite. In order to increase energy efficiency, the use of cement was minimized, as it is considered an extremely energy-inefficient material whose production requires large amounts of thermal energy, accompanied with high carbon dioxide emissions. As the physical-mechanical properties of thermal insulation are of crucial importance the paper deals with physical-mechanical properties of this material. The experimental part consisted of preparation of four mixtures with different component mass ratio, and determination of their physical-mechanical properties. The sample that showed the highest values of compressive and bending strength simultaneously was taken into thermal conductivity control tests. The thermal conductivity was measured by steady state conditions. The proposed composite material showed certain potential for practical and eco-friendly use.