The fundamentals of the grassroots and retrofit technology have been presented in Parts I and II. This part emphasises on common complications associated with deviations from the counter-current heat transfer, and the integration of streams with properties that face significant variations over the perceived range of energy recovery. A number of propositions are made with simple and straightforward modifications to the conceptual models. The modifications save the need to revert to elaborate, simulation-type models that can mire the benefits of the systematic approach. The paper further discusses the application of the technology to problems of special importance such as debottlenecking projects. It explains its potential as an analysis and a decision making tool with an example from the pulp and paper industry. A final test of its potential to remain systematic, rigorous, and fully automated, even against large scale, complicated problems, is illustrated with two Crude Oil distillation applications.