Life-Cycle Engineering and Design

ENVIRONMENTAL CONSIDERATIONS play an increasingly important role in design and development efforts of many industries. "Cradle to grave" assessments are being used not only by product designers and manufacturers, but also by product users (and environmentalists) to consider the relative merits of various available products and to improve the environmental acceptability of products. Life-cycle engineering is a part-, system-, or process-related tool for the investigation of environmental parameters based on technical and economic measures. This article focuses on lifecycle engineering as a method for evaluating impacts, but it should be noted that similar techniques can be used to analyze the life-cycle costs of products (see the article "Techno-Economic Issues in Materials Selection" in this Volume). Products and services cause different environmental problems during the different stages of their life cycle. Improving the environmental performance of products may require that industry implement engineering, process, and material changes. However a positive change in one environmental aspect of a product (such as recyclability) can influence other aspects negatively (such as energy usage). Therefore a methodology is required to assess trade-offs incurred in making changes. This method is called life-cycle analysis or assessment (LCA). Life-cycle analysis aims at identifying improvement possibilities of the environmental behavior of systems under consideration by designers and manufacturers. The whole life cycle of a system has to be considered. Therefore it is necessary to systematically collect and interpret material and energy flows for all relevant main and auxiliary processes (Fig. 1). Life-cycle analysis methods have been developed by governmental, industrial, academic, and environmental professionals in both N orth America and Europe. Technical documents on conducting LCA have been published by the Society of Environmental Toxicology and Chemistry