Environmental Engineering Reference
In-Depth Information
Step 5: optional elements of LCIA
a.
Normalization
is a tool that allows expressing impact indicator data in a way that can be
compared with other impact categories. Normalization is performed by dividing the indicator
results by selected reference values, which are selected according to different criteria, including
geographic (global, regional, or local), per capita, ratio to one another, or other basis.
b.
Grouping
involves sorting the indicators according to some criterion (e.g., local, regional,
or global impact).
c.
Weighting
implicates assigning weights to the different impact categories based on
apparent importance (EPA, 2006).
Life cycle interpretation
Life cycle interpretation is the last phase of the LCA. It is a systematic technique applied to identify,
quantify, check, and evaluate information resulting from the LCI and the LCIA (EPA, 2006).
According to ISO 14040, the interpretation needs to be consistent with the defined goal and
scope and also explain the limitations of the conducted LCA and provide recommendations.
The life cycle interpretation has three different steps, according to the ISO 14044:
1. Identification of the significant issues based on the results of LCI and LCIA phases.
Significant issues are for example inventory data (i.e., energy, emissions, waste, etc.),
impact categories (such as use of resources and climate change), and significant contribu-
tions from life cycle stages (e.g., energy production and transportation).
2.
Evaluation that considers completeness, sensitivity, and consistency checks. The purpose
of evaluation is to prove the reliability of the results of the LCA. Completeness is con-
ducted to make sure all the relevant information and data are available and complete to
proceed into the interpretation. A sensitivity check is used to evaluate the reliability of the
final results. And the consistency check is used to determine whether the assumptions and
methods are consistent with the goal and scope.
3.
Conclusions, limitations, and recommendations. The objective of this part of the interpre-
tation is to draw conclusions, recognize limitations, and make recommendations for the
audience of the LCA.
Reporting
ISO 14040 also includes guidelines about how to report the results of an LCA. These guide-
lines state that the report must be complete and accurate without bias to the intended audience,
must be transparent and presented in enough detail to allow the reader to understand the LCA,
and must include an interpretation that is consistent with the goals of the study.
Items included in the report are any modifications of the goal and scope and their justifica-
tion, system boundaries, description of the functional units, criteria for allocations, data,
choice of impact categories, and category indicators. A graphical representation of the results
of the LCI and the LCIA is suggested but not mandated by the ISO standard.
Single indicators for LCAs
It is desirable to have a single indicator that aggregates all the results of an LCA in one single
score. Several methods have been proposed, but still no score has been universally accepted.
Among the most well-known methods are EcoPoints, Environmental Priority Strategies
