Additive manufacturing with earth is an emerging but insufficiently characterized approach to create sustainable building systems. Developing standardized methods for processing 3D-printed, locally sourced earthen materials is crucial to validating the feasibility of large-scale earthen additive manufacturing for emergency shelters and climate-resilient architecture. This study evaluates the thermal transmittance (U-value) of two 3D-printed earth-based wall segments segment A with vertical infinite shape loop one air cavity aligned to the heat flux, Segment B with continuous serpentine two air cavities perpendicular to the heat flux. Experimental measurements were performed using the hotbox method for an earth-based composite was developed for construction 3d printing system, and the results were compared to numerical calculations, showing agreement within an acceptable margin of error according to the UNE EN 6946 standard. The validated model was then used to investigate the impact of incorporating rice husk insulation into the internal air cavities of the wall. The thermal performance of the enhanced 3D-printed wall was compared with that of conventional double hollow ceramic bricks. Results indicate that 3D-printed earthen walls with only air cavities (without additional insulation) can achieve U-values near 0.4 W/m2K (specifically wall segment B) and below 0.4 W/m2K when insulated (for both wall segments A and B), meeting established thermal efficiency standards and demonstrating their potential for sustainable construction.