Laboratory for Manufacturing and Sustainability

This paper presents a method of environmental assessment that incorporates the strengths of ecological footprint and process based life cycle analysis. Like ecological footprint, product ecological footprint delineates between sustainable and unsustainable consumption. The ecological footprint of individual products allows consumers to budget their consumption within this limit. The resolution of product ecological footprint can be scaled, like life cycle analysis, to compare one feature, process, or product against another. This study calculates the product ecological footprint of the generic American automobile using industry life cycle inventory, US statistical data, and data on global ecological capacity. It considers CO2 emissions, mining impacts, and land directly occupied as the major contributors of land use. The conversion of these impact categories to hectares of ecological services was performed using a top down approach, based on global supply. The sources were chosen to produce a lower-bound estimate rather than the true ecological footprint.

Based on this study, the average car owner in the US expends at least 50% (0.8 hectares) of their ecological budget on driving alone. The footprint of a car is dominated fuel efficiency. The actual footprint may range from 30% to over 100% of one's ecological budget, corresponding to fuel efficiencies between 55 mpg and 12 mpg. The ecological footprint of the average automobile is more than 800 times the area it occupies physically. The metric of land communicates environmental impact in an immediate and tangible manner. Land accurately represents the importance of ecological services over resources alone. It is one of few metrics that can compare dissimilar products and processes. Accordingly, product ecological footprint enables consumers to formulate and follow a personal ecological budget. The results of this study are designed to be meaningful to consumers and producers in hopes of provoking societal changes that will push industry towards sustainable design and manufacturing.