Assessing the Environmental Impact of Product Design Decisions Across the Life Cycle

Gordon A. Bekkal | MS | 2002

Abstract:

Throughout the stages of its life-cycle, a product generates a wide range of environmental impacts. These environmental effects can be influenced by decisions made during product design as well as the way that the consumer uses the product. A principal challenge faced in making environmentally responsible product design decisions is to establish appropriate environmental performance metrics for each stage of the product life cycle, and then to understand how the product features influence these metrics.

Past efforts to describe the environmental impact of design decisions have primarily centered on material-related effects. This work focuses on establishing a framework for describing the effect of product design changes on environmental performance during the manufacturing, use, and post-use stages of the product life cycle as well as determining the dynamic use stage characteristics. The features of the use stage will be used in a framework to describe the complete life-cycle performance of a product. The product chosen to illustrate the life-cycle analysis is a bench-top heat exchanger.

In the use stage, the environmental impacts are extracted from the time series data. This attempts to bypass the complex process mechanics by implementing Data Dependent Systems (DDS) methodology. The measurements collected were used to develop Auto-Regressive Moving Average Models. The process is then quantified using the characteristics of the DDS models, specifically the roots which provide natural frequencies and damping ratios. The dynamics are critical due to the variation of inputs and set-point temperature. These characteristics are subsequently related to the environmental performance in the use stage. A statistical design of experiments is used to determine the significance of design variables.

The framework employed to address the environmental design problem is presented taking advantage of the previous analysis. This framework addresses changes in product design variables such as material type, part complexity and the post use option across the life-cycle. Changes in these product design variables are then related to environmental performance measures or metrics across the life-cycle. This approach is unique in that sufficient details are retained in the analysis to actually link specific product characteristics to environmental measures. A carefully arranged design of experiments evaluates the significance of several design variables (e.g., coil material, coil length, and case construction). Spider charts are used to present the data and compare different designs. Weighting and scaling of the metrics is discussed. Robust design, i.e., the selection of design variable settings that are insensitive to consumer decisions, are used to interpret the environmental performance measures. The metrics considered in the study include energy use during operation, energy requirements for manufacture, and disposal costs.

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