By: Rumanda Young
Life Cycle Assessment (LCA) is touted as the premier green decision-making tool (i.e., which product or process has less negative impact on the environment). I agree it is important to determine the sustainability of products or activities by looking at all environmental impacts throughout the product or activity life cycle, including product manufacture, selection, use, maintenance and end-of-life disposal. However, it is incredibly difficult to truly capture a system boundary. In fact, defining the boundary of a system is the most complicated step in the LCA process. The more complex and difficult a system boundary becomes, the more accurate and reliable the results.
Theoretically, a complete life cycle system includes all raw materials and energy sources taken from the earth and ends with all materials either returned (with good or bad consequences) to the earth. Any system boundary delineation for LCA that falls short of this “full circle” boundary is limiting the analysis and conclusions regarding the total system cannot be drawn. Depending on the goal of a study, this may be advantageous. When using the LCA as a tool to compare and evaluate tradeoffs, the analyst must take into consideration anything that limits the system boundary of one product or process, so that the analysis is not skewed. However, too limited a boundary may exclude consequential activities or elements and statements, and findings about the total system impact cannot be reasonably made. The bottom line is that study conclusions are exceedingly sensitive to system boundary delineation. My final thought is that applications and the role of LCA-based information should be interpreted only as far as the system boundary allows, and LCA should be one among several inputs to the environmental decision-making process.
