Life Cycle Analysis : Scope

The scope definition serves the purpose of communicating to the audience what is included and what is excluded. Depending on the goal, there are several types of scopes including cradle-to-gate, cradle-to-grave, and gate-to-gate. There are other words commonly used to describe these scopes:

• Cradle-to-grave: includes all flows and impacts from obtaining raw material to disposal and reuse
• Crade-to-gate: includes all flows and impacts from raw material to production, but excludes product use and end of life.
• Gate-to-gate: only includes flows from production or material processing steps of a product life.

The scope must be carefully selected in consideration of the potential implications not including product stages or phases in the scope of the work. For example, a product may have lower product emissions, but have a shorter lifetime than an alternative product that would not be communicated in a process stage diagram as seen in Figure 1.1

. These types of diagrams list the major unit steps considered and clearly show what is not included. 

Figure 1.1

 System boundary diagram of a cradle-to-grave biofuels process.

Temporal boundaries are also established in the scope. Assumptions relating to time can have a large influence on the results. A study timeframe should be picked which will best capture the impacts of the product or processes. A 100-year window is a common temporal boundary, for example, in global warming. In a 100-year temporal window, impacts occurring after 100 years are not part of the overall analysis.

Other aspects to be included in scope are technology and geographical regions. Many studies are spatially dependent so LCA results are not broadly applicable to other regions. Products or services from older technologies often have different impacts than current technologies. Thus, it is important to communicate the type and stage of the technology. In addition, allocation procedure impact assessment methods and should be reported.