Development of metrics for streamlined life cycle assessments : a case study on tablets

Abstract

Growing concern about climate change and human impact on the environment have resulted in an increase in interest for evaluating the environmental impact of products and services we consume. Life cycle assessment (LCA) has become the most prominent method for environmental evaluation. Life cycle assessment is the quantification of the environmental impacts of a product or service through its whole life cycle, from the extraction of materials to manufacturing and end of life. A carbon footprint is a subset of an LCA. LCAs are required as part of government regulations, used by companies to identify high resource use in their supply chain or to choose between product designs and by consumers to choose between alternative product choices. LCAs provide valuable information; however, they are resource intensive, time consuming and uncertain. Therefore, a methodology that addresses all these issues is needed. This study addresses the following question: Can LCAs be streamlined while still providing useful information? To answer this, an under-specification, probabilistic screening methodology is employed. The screening methodology uses a high level assessment of the footprint, incorporates uncertainty in the inputs, and refines data around the primary drivers of impact. The streamlined LCA procedure is extended to include a Sobol based sensitivity analysis methodology for identifying high impact activities. The effects of partial perfect information in subsequent data acquisition activities on the streamlining methodology are examined. Metrics to determine sufficiency in the data gathering procedure and to determine whether decision makers can sufficiently distinguish between two products or design alternatives are developed. A procedure to quantify the cost of additional information is developed. Finally, an exploration of the scenario space of the impacts is analyzed. The extended streamlined methodology is applied to a case study on tablets, with a focus on integrated circuits. This thesis finds that the streamlined, probabilistic methodology can be used to cost-effectively evaluate the environmental impact of products while still taking uncertainty into account. Metrics to determine sufficiency can be effectively used, and the presence of partial information does not limit the usefulness of the metrics. Furthermore, quantifying the cost of additional information can help determine sufficiency in data collection efforts and can help understand the challenges that companies face when performing an LCA.