Sustainability assessments are dependent on accurate measures for energy, material, and other resources used by the processes involved in the life cycle of a product. Manufacturing accounts for about 1/5 of the energy consumption in the U.S. Minimizing energy and material consumption in this field has the promise of dramatically reducing our energy dependence. To this end, ASTM International  has formed both a committee on Sustainability (E60) and a Subcommittee on Sustainable Manufacturing (E60.13). This paper describes ASTM’s new guide for characterizing the environmental aspects of manufacturing processes . The guide defines a generic representation to support structured processes. Representations of multiple unit manufacturing processes (UMPs) can be linked together to support system-level analyses, such as simulation and evaluation of a series of manufacturing processes used in the manufacture and assembly of parts. The result is the ability to more accurately assess and improve the sustainability of production processes. Simulation is commonly used in manufacturing industries to assess individual process performance at a system level and to understand behaviors and interactions between processes. This paper explores the use of the concepts outlined in the standard with three use cases based on an industrial example in the pulp and paper industry. The intent of the use cases is to show the utility of the standard as a guideline for composing data to characterize manufacturing processes. The data, besides being useful for descriptive purposes, is used in a simulation model to assess sustainability of a manufacturing system.