The paper presents an energetic post-processing methodology for large-scale vibro-acoustic finite element models. Starting from a dynamic and an acoustic modal basis produced by a finite element analysis (FEA), the methodology produces: 1synthetic and pertinent energetic outputs; 2optimal SEA partitions of the finite element mesh; 3quality indicators of existing SEA partitions. The methodology involves six different steps, some required, some optional: 1automatic partitioning of the FEA model in patches; 2calculation of distribution matrices; 3definition of mechanical loads; 4definition of damping characteristics; 5modal-based vibro-acoustic response calculation; 6energetic post-processing; 7automatic partitioning in SEA subsystems; 8verification of existing SEA partitions. Each step will be presented in turn. The methodology will be illustrated by application of the successive steps to a Renault Laguna body and an Alstom two-storey TGV train section.