Life-Cycle Assessment and Environmental Engineering

Abstract

Life-cycle assessment (LCA) is an analytical framework for measuring environmental and social impacts of a product system or technology across its entire life (ISO 1997), and it supplies a basis for selecting among competing options. This editorial argues that LCA and related tools should be both integral and integrated with practice and scholarship in environmental engineering. Readers not familiar with LCA may consult the references listed below. In brief, LCA encompasses four objective, factbased procedures: In the LCA jargon, the “goal and scope definition” phase defines the aims, product/system, and system boundaries. System boundaries typically range from raw materials extraction and processing, manufacturing, product use, and final disposal. In the “inventory analysis,” air emissions, waterborne effluents, solid wastes, other releases to the environment, energy and materials consumption, and other aspects are quantified for the defined system boundary and related to the product/system function. In “impact assessment,” the inventory’s outputs or burdens are analyzed with respect to environmental relevance, and outcomes are aggregated to a smaller number of relevant environmental categories to address short- and long-term impacts on human health and the environment. Aggregations usually address depletion of abiotic resources, depletion of biotic resources including impacts of land use and loss of biodiversity and life support function, greenhouse effect, stratospheric ozone depletion, ecotoxicity, photo-oxidant formation, acidification, eutrophication, odor, noise, radiation, waste heat, human toxicity, and casualties. In the “interpretation” step, the results are compared with the goal of the study. LCA is also an important tool for “life-cycle design” or “product improvement” where environmental considerations are integrated into product/system development. There are many variants on these themes, and many tools other than LCA with similar aims—e.g., “material flow analysis,” “design for the environment,” “green chemistry,” and “environmentally conscious manufacturing.” There is growing experience with the LCA framework in a wide range of analyses, ranging from everyday items that are well-recognized by the public, e.g., fast-food containers (paper versus plastic clamshell case—or bring-your-own ), to large-scale engineering systems, e.g., transportation and fuels infrastructure. In the environmental engineering field, LCA should have special meaning and consequence as it identifies, quantifies, and assesses the principal environmental burdens—pollutant discharges, environmental impacts, and health risks—that are associated with the system under analysis and that have been the focus of the field for decades. However, LCA studies are (or can be) holistic and much