Page 186 - Materials Chemistry, Second Edition

172 R.K. Rosenbaum et al.

ISO 14044 (2006b) states that the choice of impact categories needs to assure
that they
• Are not redundant and do not lead to double counting
• Do not disguise significant impacts
• Are complete
• Allow traceability
Furthermore, this list is complemented with a number of obligatory criteria,
requiring that the selection of impact categories, category indicators and charac-
terisation models shall be:
• Consistent with the goal and scope of the study (when, for example, environ-
mental sustainability assessment is the goal of a study, the practitioner cannot
choose a limited set of indicators, or a single indicator footprint approach, as this
would be inconsistent with the sustainability objective of avoiding
burden-shifting among impact categories)
• Justified in the study report
• Comprehensive regarding environmental issues related to the product system
under study (essentially meaning that all environmental issues—represented by
the various impact categories—which a product system may affect need to be
included, again in order to reveal any problem-shifting from one impact cate-
gory to another)
• Well documented with all information and sources being referenced (in practice
it is normally sufficient to provide name and version number of the LCIA
method used together with at least one main reference, which should provide all
primary references used to build the method)
ISO 14044 (2006b) recommendations for the selection of impact categories,
category indicators and characterisation models by a practitioner include:
• International acceptance of impact categories, category indicators and charac-
terisation models, i.e. based on an international agreement or approved by a
competent international body
• Minimisation of value-choices and assumptions made during the selection of
impact categories, category indicators and characterisation models
• Scientific and technical validity of the characterisation model for each category
indicator (e.g. not based on unpublished or outdated material)
• Being based upon a distinct, identifiable environmental mechanism and repro-
ducible empirical observation
• Environmental relevance of category indicators
Numerous further criteria but also practical constraints beyond ISO 14044 exist
and are applied, consciously or unconsciously, often based on experience or rec-
ommendations from colleagues. In practice the selection of impact categories,
category indicators and characterisation models usually boils down to selecting an