It has been shown that the effective thermal conductivity of anisotropic composite material (well conducting media with regular cavities of the air) can be studied by numerical modelling. The influence of the orientation and size of the cavities on the effective thermal conductivity of the structure as well as the role of the convective and radiation heat transfer in the process has been examined. It has been shown that effective thermal conductivity of the structure close to that of Keraterm is lower in case the cavities are oriented perpendicularly to the heat flux direction than in case the cavities are oriented parallelly to the heat flux direction.