Fecha de publicación: -- Fuente: Materials The increasing demand for sustainable construction materials has led to renewed interest in earthen composites, particularly light clay, due to their low embodied energy, biodegradability, and favorable thermal properties. This study experimentally investigates the thermal performance of light earth composites with straw and hemp. Rectangular samples were prepared using a controlled protocol to ensure consistent density and homogenous aggregate dispersion. Key parameters, including aggregate type, aggregate content, aggregate length, and orientation, were investigated to assess their influence on thermal conductivity and specific heat capacity. Thermal conductivity was measured using the Guarded Hot Plate method, while specific heat capacity was determined via Differential Scanning Calorimetry (DSC). Results indicate a strong dependence of thermal conductivity on aggregate type and content, with straw-composites achieving lower values (0.055–0.146 W/m·K) compared to hemp (0.102–0.199 W/m·K). Increased aggregate content and longer aggregate lengths further reduced thermal conductivity by enhancing porosity and air entrapment. Specific heat capacity ranged from 890 to 994 J/kg·K, slightly increasing with higher aggregate content due to the higher Cp values of the plant-based aggregates. These findings highlight the potential of plant-based aggregates to improve the insulating performance of earthen composites, supporting their application in sustainable, energy-efficient building envelopes. The study provides quantitative data critical for standardizing the thermal characterization of plant-based aggregates in earthen materials and advancing their integration into modern low-energy construction.