Non-destructive evaluation of thermal conductivity in wood materials using dielectric property measurements with ground penetrating radar

Accuracy and effectiveness of predicting the heat transfer in constructive materials are increasingly important for energy performance and provide crucial insights into building inspections. However, directly establishing thermal conductivity for architecture walls is challenging and time-consuming, and existing measurement methods are highly technical with restrictive boundary conditions. Therefore, we propose a data-driven method, predicting thermal conductivity from relative permittivity using ground-penetrating radar (GPR) non-destructive technique rather than direct measurement. The experiments were conducted on spruce, fir, beech and pine using GPR measurement at 2.6 GHz frequency and heat flow meter method. Our results indicate a strong linear correlation between thermal conductivity and dielectric properties, independent of wood species and type (hardwood or softwood). This correlation suggests that thermal conductivity can be accurately estimated through dielectric property measurements, demonstrating the potential for predicting thermal conductivity using GPR. This approach can be used on site, simplifies the measurement process, eliminating the need for direct thermal conductivity assessments and steady-state conditions.