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Unformatted text preview: Env. Sci. & Tech. Policy Analysis April 1, 1998 / Volume 32, Issue 7 / pp. 184 A-191 A Page 1 of 17 GREEN DESIGN Economic Input-Output Models for Environmental Life-Cycle Assessment CHRIS HENDRICKSON AND ARPAD HORVATH Dept. of Civil and Environmental Engineering Carnegie Mellon University Pittsburgh, PA 15213 SATISH JOSHI Heinz School of Public Policy and Management Carnegie Mellon University Pittsburgh, PA 15213 LESTER LAVE Graduate School of Industrial Administration Carnegie Mellon University Pittsburgh, PA 15213 Process and product models are commonly used for performing life-cycle assessments (LCAs) of the environmental impacts of materials and products through different stages of fabrication, use, and end-of-life options. In this article, we show that these models can be represented as process flow diagrams or as matrices of process interactions. In either representation, the inventory of environmental emissions and resources used is comparable, provided the process models are proportional in nature (any increase in product output produces a corresponding environmental burden). Matrix representations are advantageous if application cost, feedback flow, or speed of analysis is important. They are also useful in conjunction with comprehensive, general equilibrium models in which the system boundary of the problem (e.g., an LCA of a product) being analyzed is on the level of the national economy. Life-cycle assessment (LCA) is an important tool used in pollution prevention and green design efforts. Selection of product design, materials, processes, reuse or recycle strategies, and final disposal options requires careful examination of energy and resource consumption as well as environmental discharges associated with each prevention or design alternative. To accomplish this task, LCA models have been developed and software products are available. The International Organization for Standardization (ISO) 14000 international standards for environmental management systems are being developed to formalize the LCA method components ( 1- 3 ). Efforts within the United States to develop LCA methodology are being led by the Society for Environmental Toxicology and Chemistry (SETAC) and EPA. The SETAC-EPA LCA approach focuses first on manufacturing processes (such as the manufacture of paper drinking cups), estimating fuels consumed, other resources used, and the amount of each waste discharged into the environment. The procedure then estimates the resources consumed and environmental discharges produced by the most Env. Sci. & Tech. Policy Analysis April 1, 1998 / Volume 32, Issue 7 / pp. 184 A-191 A Page 2 of 17 important upstream suppliers (in the paper cup example, these would include paper mills, pulp mills, and logging operations) and downstream activities (recycling and disposal)....
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