The WAR algorithm, a methodology for determining the potential environmental impact (PEI) of a chemical process, is presented with modifications that account for the PEI of the energy consumed within that process. From this theory, four PEI indexes are used to evaluate the environmental friendliness of a process design. These indexes are used in a comparative manner in the process design stage to help minimize the environmental impact of that process. Eight PEI categories (four global and four toxicological) are used in the evaluation of the PEI indexes. Details for relating these categories to known or measured quantities are also presented. An illustrative case study is presented which provide an example for the intended use of the WAR algorithm within the scope of process design and simulation.