  Understanding heat transport in semiconductors and insulators is of
fundamental importance because of its technological impact in electronics and
renewable energy harvesting and conversion. Anharmonic Lattice Dynamics
provides a powerful framework for the description of heat transport at the
nanoscale. One of the advantages of this method is that it naturally includes
quantum effects due to atoms vibrations, which are needed to compute the
thermal properties of semiconductors widely used in nanotechnology, like
silicon and carbon, even at room temperature. While the heat transport picture
substantially differs between amorphous and crystalline semiconductors from a
microscopic standpoint, a unified approach to simulate both crystals and
glasses has been devised. Here we introduce a unified workflow, which
implements both the Boltzmann Transport equation (BTE) and the Quasi Harmonic
Green-Kubo (QHGK) methods. We discuss how the theory can be optimized to
exploit modern parallel architectures, and how it is implemented in $\kappa
ALDo$: a versatile and scalable open-source software to compute phonon
transport in solids. This approach is applied to crystalline and partially
disordered silicon-based systems, including bulk silicon and clathrates, and on
silicon-germanium alloy clathrates with largely reduced thermal conductivity.
