Page 350 - Materials Chemistry, Second Edition

334 5 Life Cycle Interpretation, Reporting and Critical Review

The goal of the sensitivity check is to estimate the uncertainties in the results of
an LCA due to data quality, cut-off criteria, choice of allocation rules and selection
of impact categories. Mostly the scenarios that are investigated are those that differ
in the modelling of the product system, which is the main scenario, with respect
to one single parameter of investigation. The allocation rule may, for instance, be
altered. It would then be examined whether this would imply profound changes in
the results.
A sensitivity check allows in a descriptive way to determine and document the
influence of the altered parameter on the final result. The following are the possible
results of sensitivity analyses:
• The altered parameter does not modify or insignificantly modifies the results.
• Further detailed sensitivity analyses are required.
• The results are only valid within margins, which needs to be considered within
the conclusions.

The consistency check provides reference to the first phase of LCA (goal and scope
definition). ISO 14044 states (see Section 4.5.3.4),
The objective of the consistency check is to determine whether the assumptions,
methods and data are consistent with the goal and scope.
Besides the already addressed consistency within a product system, an examination
is particularly necessary as to whether for comparative LCAs on different product
systems, the following issues are identical or at least similar:
• Data quality
• Regional and time-related validity of data
• Allocation rules and system boundaries
• Constituents of the impact assessment.
In the following section, the techniques necessary for an evaluation are discussed
on the basis of the scientific literature.

5.3
Techniques for Result Analysis

5.3.1
Scientific Background

LCA is often regarded as a support for decision-making within product compar-
ison and optimisation 13) applied in the context of the ‘environmental pillar’ of
sustainability (see Chapter 6). ISO 14040 lists the following direct applications of
an LCA, which are, however, not part of the standard:

13) Grahl and Schmincke (1996), Hofstetter (1998), Sepp¨ al¨ a (1999), Tukker (2000), Heijungs (2001),
Hertwich and Hammit (2001), Werner and Scholz (2002), Hertwich (2005) and Heijungs et al.
(2005).