Page 91 - Materials Chemistry, Second Edition

LIFE CYCLE IMPACT ASSESSMENT 73

1. Normalization - calculation of the magnitude of category indica-
tor results relative to reference information;
2. Grouping - sorting with the aim of possibly reducing the number
of impact categories, as well as possibly ranking them in order of
importance;
3. Weighting - converting and possibly aggregating indicator results
across impact categories using numerical factors based on value-
choices; data prior to weighting should remain available; and
4. Data Quality Analysis - developing a better understanding of the
reliability of the indicator results in the LCIA profile.

The optional LCIA elements may use information from outside the LCIA
framework. The use of such information should be explained and the explana-
tion should be reported. The application and use of normalization, grouping
and weighting methods shall be consistent with the goal and scope of the LCA
and fully transparent. All methods and calculations used shall be documented
to provide transparency (EC-JRC 2010b).

4.2.4 Interpreting an LCIA Profile

The interpretation phase of LCA entails the evaluation of the results of the
inventory analysis along with the results of the impact assessment to aid in the
decision making process, whether it is to select the preferred product, improve
a process or service, etc. with a clear understanding of the uncertainty and
the assumptions used to generate the results. Very seldom will the results of
an LCA identify a clear "winner" between alternatives. In some cases, it may
not be possible to state that one alternative is better than the others because of
the uncertainty in the final results. This does not imply that efforts have been
wasted or that LCA is not a viable tool for decision makers. The LCA pro-
cess will still improve understanding of the environmental and health impacts
associated with each alternative, where they occur (locally, regionally, or glob-
ally), and the relative magnitude of each type of impact in comparison to each
of the proposed alternatives included in the study. This information more fully
reveals the pros and cons of each alternative.
While conducting the LCA (within both the LCI and LCIA) it is necessary
to apply various modeling assumptions and engineering estimates. At times
these choices are based on the values held by the modeler, or by the person
who commissioned the study. Therefore, every choice must be stated and the
impact on the decision clearly communicated within the final results to com-
prehensively explain conclusions drawn from the data.
ISO (2006a) defines two objectives of life cycle interpretation:

1. Analyze results, reach conclusions, explain limitations, and pro-
vide recommendations based on the findings of the preceding
phases of the LCA, and to report the results of the life cycle inter-
pretation in a transparent manner.