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companies, literature review, and building models in LCA software. Material flows
in and out of processes, types of materials, product life time, and product energy
requirements are examples of data typically collected in the LCI phase.
5.2.3 Life-Cycle Impact Assessment
The life-cycle impact assessment (LCIA) step of the analysis process takes LCI data
and computes values that represent some form of environmental impacts. This process
simplifiesthedatasetfromhundredsofflowsinto10orlessimpactcategoriesthatcan
then be used for decision making. There are many different methods for LCIA based
on location, goal, and scope of the study.
5.2.4 Interpretation
The interpretation step of LCA reflects on what was found in the other steps to create
new knowledge. It should be noted that the interpretation step is not the last step;
rather it is continually done throughout each process. When this is done in each stage,
study assumptions, goals and scopes, and methods are often refined to create to better
suit the needs of the study commissioner.
5.3 Life-Cycle Assessment Steps
5.3.1 Goal, Scope, System Boundaries
5.3.1.1 Goal Definition
The first step of an LCA is defining the goal of the study. In this part of the LCA, the aim
of the study and breadth and depth of the study are communicated. There are two types
of LCA purposes: descriptive and change-oriented. A descriptive LCA generally looks
at broader aspects of an issues, for example, how much of the world’s global warming
impact can be attributed to transportation. These larger environmental questions are
answered by descriptive LCAs. The second purpose of an LCA is a change-oriented
LCA where two decision options for fulfilling a function are compared. Some typical
examples of change-oriented LCAs are paper versus plastic bags, and flying versus
driving your car. These types of studies can guide the audience in ways to reduce
environmental impacts through changing behaviors based on the findings of the LCA.
The intended audience is another aspect of the goal and scope, which is important
to communicate. The audience can include interest groups such as policy makers,
company marketing groups, or product development teams. Additionally, the involved
interest groups and parties should be identified. These include companies, funding
sources, target audiences, and expert reviewers. It is noted that the intended use of
the LCA can be different from the end use as the information may be relevant to other
decisions and analysis beyond the original intent.
One specific type of LCA used to compare two different products is a “comparative
assertion disclosed to the public.” In this type of study, “environmental claim regarding
the superiority or equivalence of one product vs a competing product which performs
the same function” are communicated to the public. These types of studies must follow
the ISO 14044 standards including the nine steps required for a “comparative assertion.”
