The aim of this work is the study of the thermal flux through a multilayer insulation specimen, whose final panels could be designed for the green building field. The specimen was fabricated using an expanded styrofoam base, the mortar and milk cements, a fiberglass, and hemp fibers chopped and scattered into a surface smoothing. The dimensions of the specimen are 230 x 75 x 30.2 [mm]. The need to analyze a reduced surface in the development of a 3D visualization follows a computational aspect, i.e., to limit the number of degrees of freedom to be solved. Specifically, the research is focused on a comparative analysis among numerical simulations through the data processing by means of Matlab (R) - using the finite difference method (FDM) in the 1D domain -, and Comsol Multiphysics (R) - using the finite element method (FEM), both in 2D and 3D domains -. In addition, an experimental analysis centred on the detecting of the sub-superficial fiberglass by means of infrared thermography (IRT) technique is carried out. A specific Matlab (R) script was also implemented. Finally, can be observed that Comsol Multiphysics (R) not only allows a visualization of the flow, as it is done in Matlab, but also of the entire specimen geometry with the possibility of realizing a video of the thermal transient during the heating and cooling phases.