Reliability of statistical energy analysis (SEA) models depends on good estimates of coupling loss factors (CLFs), modal densities, and damping loss factors. Statistical modal energy distribution analysis (SmEdA), a finite element based method to compute CLFs from uncoupled finite elements models of subsystems, is used to generate SEA CLF for general subsystems. This method is based on the basic SEA relations for coupled oscillators and on a dual modal formulation to describe the vibration of coupled subsystems. Previous works have demonstrated the use of the SmEdA method for structure-to-structure couplings. The current work extends the SmEdA process to structure-to-cavity couplings. The estimation of CLF using the SmEdA approach is compared, for a simple test case, to analytical results and a classical expression obtained with a wave approach. Results show good comparison with analytical results even below critical frequency, where the wave approach underestimates CLF. Finally, an industrial application has been carried out to demonstrate that the SmEdA approach can be used in the case of complex structures.