3D-printed earth-fiber Envelopes: Optimization of thermal performance and industrial applicability

3D printing with earth-based materials is emerging as a sustainable building method; however, challenges remain regarding strength, thermal performance, and both logistical and environmental viability. This study aims to optimize the passive thermal performance and facilitate the industrial applicability of printed envelopes through advanced material and geometric design; implementing a mass-customizable computational toolpath framework, and refining the printing processing parameters. The design approach is guided by experimental exploration and the integration of state-of-the-art knowledge. The results present a high-strength material mix with over 55 vol% fiber-content, including fibers several centimeters in length, printed using an 8 mm nozzle outlet. The medium-resolution printing method balances efficiency, shape accuracy, and thermal performance. Mechanical tests showed that small, lab-cast specimens achieved compressive strengths of up to 10.6 MPa, surpassing typical cob-like materials. Likewise, thermal conductivity measurements of approximately 0.35–0.37 W/m·K confirm the material's potential for passive temperature regulation. Furthermore, by segmenting the wall into repeatable yet customizable units and integrating cavities and ventilation channels, the system can be adapted to different building sizes, performance requirements, and assembly methods. Full-scale prototypes were printed to evaluate the applicability in buildings. While load-bearing capacity remains limited, results suggest that 3D-printed earth-fiber walls up to 30 cm thick can achieve simulated U-values of approximately 0.8–0.9 W/m²·K. These findings demonstrate that engineered fiber-earth composites, combined with strategic toolpath design, can enhance both mechanical and thermal performance in earthen construction.