High thermal conductivity is required for high performance electronics and one advantage of carbon nanomaterials as candidates for future electronics is that they have peculiar thermal conductivites. The effects of Anderson type disorder to lattice thermal conductivity through long carbon nanotubes (CNTs) using atomistic Green functions will be discussed. The dependence of phonon transmission is analyzed as a function of the length of the disordered CNT, thermal conductance as a function of temperature is calculated for different lengths. Analysis of transmission amplitudes as a function of length of the disordered device shows that phonons with different energies display different transport regimes, i.e. quasi-ballistic, diffusive and localization regimes coexist. In the light of the results implications for heating of the semiconductor CNT device in electronic applications are discussed.