The purpose of this study was to compare thermal and mechanical properties of different materials based on vegetal aggregates and clay in order to characterize the performances of four different biocomposites with a view to valorizing agricultural waste. The samples analyzed were manufactured with four different plant-based aggregates (rape straw, sunflower bark, sunflower pith and a mix of sunflower pith and bark) at a same binder/aggregate ratio. These materials revealed a wide range of densities and thermo-mechanical properties. As expected, increasing the material’s density gave a higher compressive strength while at the same time increasing thermal conductivity.