This study deals with a comprehensive efficiency investigation of a TEMA "E" shell and tube condenser through exergy efficiency as a potential parameter for performance assessment. Exergy analysis of condensation of pure vapor in a mixture of non-condensing gas in a TEMA "E" shell and tube condenser is presented. This analysis is used to evaluate both local exergy efficiency of the system (along the condensation path) and for the entire condenser, i.e., overall exergy efficiency. The numerical results for an industrial condenser with a steam-air mixture and cooling water as working fluids indicate significant effects of temperature differences between the cooling water and the environment on exergy efficiency. Typical predicted cooling water and condensation temperature profiles are illustrated and compared with the corresponding local exergy efficiency profiles, which reveal a direct (inverse) influence of the coolant (condensation) temperature on the exergy efficiency. Further results provide verification of the newly developed exergy efficiency correlation with a set of experimental data.