Many plants presently incorporate mass and heat integration schemes because they can offer substantial material and energy savings. In designing such integrated processes, the designer runs the risk of designing plants with operational difficulties. It is prudent to carry out a detailed operability analysis before finalizing a process design. In this article, we present an extension to the operability framework of Vinson and Georgakis (in DYCOPS-5, 5th IFAC Symposium on Dynamics and Control of Process Systems, Pergamon Press, 1998, and J. Process Control 2000, 10, 185 - 194) to aid us in the analysis of plantwide systems. It is shown that the feasible operating region in the production-related variables, named here as achievable production output space (APOS), can be used to compare competing process designs. We also show that the same analysis tool can be used to discriminate among several control structures for a given plant design. The proposed methodology is demonstrated with a CSTR-stripper process and the well-known Tennessee Eastman process of Downs and Vogel.