Page 216 - Materials Chemistry, Second Edition

200 4 Life Cycle Impact Assessment

• Because some subjectivity is inevitable in the course of the ranking it is to
be made certain that all phases in an LCA are presented with transparency
and comprehensibly.
• If in two LCAs different grouping methods are used, the results of the
element ‘grouping’ are not directly comparable.

4.3.3.3 Weighting
The designation weighting can be regarded as replacement for ‘valuation’, which
according to ISO standards is to be strictly avoided and thereby performs the
function of an euphemism. In contrast to the element ‘grouping’, numerical
46)
factors are admitted which are based on value choices :
Weighting is the process of converting indicator results of different impact categories
by using numerical factors based on value-choices. It may include aggregation of
the weighted indicator results.

In the last sentence of the quotation the possibility of ecopoints and similar
aggregations is implicitly suggested. These methods are also called single point
methods because in the context of weighting all considered impact categories are
quantitatively taken into account but only a highly aggregated result is documented.
This synopsis of category indicator results cannot be justified scientifically: Rather,
value-based decisions must be made as to which weighting factor is applied and
to which impact category. Also an equal weighting of all impact categories is a
value-based decision. It can thus be concluded that weighting is inappropriate
for the phase LCIA and should be integrated into the phase interpretation (our
47)
‘ceterum censeo’ for many years, see also ). In LCAs intended for comparative
assertions that are intended to be made accessible to the public, the optional
element ‘weighting’ must not be used (ISO 14044). 48) It can be concluded that
‘single point methods’ if used for comparative assertions are only permissible for
internal use, not for marketing or statements in the press or other media.
The much used single point (often called ecopoint) methods are the Swiss
‘ecofactors’ , the Swedish EPS (enviro-accounting) method 50) as well as the Dutch
49)
eco-indicator. The latter is integrated into the widespread LCA software ‘SimaPro’.
51)
Common to all single point methods is the loss of information due to a simplified
representation of the final result. For an aggregation, valuation or weighting factors
must inevitably be introduced that, even though described by the authors, are often
not present to the user. The methods are against the spirit as well against the
wording of the standards ISO 14040 and 14044. These disadvantages have, partic-
ularly in Germany, led to a widespread refusal of these procedures and initiated

46) ISO (2006b, Section 4.4.3.4).
47) Reap et al. (2008a,b).
48) ISO (2006b, Section 4.4.5).
49) BUWAL (1990, 1998) and Frischknecht, Steiner and Jungbluth (2009).
50) Steen and Ryding (1992).
51) Goedkoop (1995) and Goedkoop et al. (1998); http://www.simapro.de; http://www.pre.nl.