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2.4 Interpretation
Conducting Life Cycle Assessments
In the interpretation phase the results are checked and evaluated to see that they are
consistent with the goal and scope definition and that the study is complete. This phase
includes two primary steps:
1. identification of significant issues;
2. evaluation (described below).
The life cycle interpretation is an iterative procedure both within the interpretation phase
itself and with the other phases of the LCA. The roles and responsibilities of the various
interested parties should be described and taken into account. If a critical review has been
conducted, these results should also be described.
2.4.1 Identification of significant issues
The first step of the life cycle interpretation phase is to structure the results from the LCI
and LCIA, and identify the “significant issues” or data elements that contribute most
significantly to the results of both the LCI and LCIA for each product, process or service.
The identification of significant issues guides the evaluation step. Because of the
extensive amount of data collected, it is only feasible, within reasonable time and
resources, to assess the data elements that contribute significantly to the outcome of the
results. Significant issues can include:
Inventory elements such as energy consumption, major material flows, wastes and
emissions etc.
Impact category indicators that are of special interest or whose amount is of
concern.
Essential contributions of life cycle stages to LCI or LCIA results such as individual
unit processes or groups of processes (e.g., transportation, energy production).
The results of the LCI and the LCIA phases are structured to identify significant issues.
These issues should be determined in accordance with the goal and scope definition and
iteratively with the evaluation phase. The results can be presented in form of data lists,
tables, bar diagrams or other convenient forms. They can be structured according to the
life cycle phases, different processes (energy supply, transportation, raw material
extraction etc), types of environmental impact or other criteria.
2.4.2 Evaluation
The goal of the evaluation is to enhance the reliability of the study. The following three
methods should be used for the evaluation:
Completeness check: In the completeness check, any missing or incomplete
information will be analyzed to see if the information is necessary to satisfy the
goal and scope of the study. Missing data have to be added or recalculated to fill
the gap or alternatively the goal and scope definition can be adjusted. If the
decision is made that the information is not necessary, the reasons for this should
be recorded.
Sensitivity check: The sensitivity check determines how the results are affected
by uncertainties in the data, assumptions, allocation methods, calculation
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