System Boundaries

Once the purposes for preparing an LCI are determined, the analyst should specifically define the system. (A system is a collection of operations that together perform some clearly defined functions.) In defining the system, the analysts must first set the system boundaries. A complete LCI sets the boundaries of the total system broadly to quantify resources, energy use, and environmental releases throughout the entire cycle of a product or process, as shown in Figure 3.4.1. For example, the three steps of manufacturing are shown in Figure 3.4.2.

As shown in Figure 3.4.1, a life cycle comprises the four stages described next.

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