Page 308 - Materials Chemistry, Second Edition

292 4 Life Cycle Impact Assessment

exist. The following illustration of the phase impact assessment on the basis of a
case example 368) is done as outlined in Section 4.3.
Mandatory elements:
1. Selection of impact categories, – indicators and characterisation factors
(Section 4.6.1):
These specifications according to ISO 14040/44 are to be determined in
the first phase, ‘definition of goal and scope’, as data procurement in the
inventory must guarantee that the required data for the selected impact
categories are available (see Chapter 2). The detailed discussion takes
place here, as the scientific background of the consideration of impact
categories was discussed in Section 4.5. A fundamental examination is
necessary whether all inputs and outputs that have been quantitatively
considered are able to map to the selected impact categories. If this is
not the case there are two possibilities: either the inventory has to be
revised or impact categories with insufficient data quality have to be
discarded.Because of the absence of a list of impact categories in ISO
14044 mandatory for all LCAs (see Section 4.3.2.1), the selection in each
study has to be comprehensible and transparent and must be justified.For
many impact categories, indicator models with impact indicators have
been established. For others like, for example, ‘human or ecotoxicity’,
quite diverse models are used by different working groups (see Section
4.5.3). Therefore indicator models used in the study should also be
comprehensible and transparent.
2. Classification (Section 4.6.2):
The classification in each study is accomplished for the selected impact
categories. The inventory data are ordered according to their scientifi-
cally established contribution to the selected impacts categories: they are
ordered in classes (hence the name ‘classification’).
3. Characterisation (Section 4.6.3):
By the selected indicator models for the considered impact categories
the inventory data assigned by classification are transferred into impact
indicators. This is done by means of characterisation factors.
Optional elements:
4. Normalisation (Section 4.6.4):
If a normalisation is accomplished the reference quantities must be
defined.
5. Grouping (Section 4.6.5):
If the normalised data are further ordered (sorted or ranked) according
to their relevance, the ordering criteria must be represented with trans-
parency. That is particularly important as value-based elements start to
enter here.

368) IFEU (2006).