ILCD Handbook: Framework and requirements for LCIA models and ...

ILCD Handbook: Framework and requirements for LCIA models and indicators First edition
A – Full compliance
B – Compliance in all essential aspects
C – Compliance in some aspects (or acceptable agreement made)
D – Little compliance
E – No compliance.
For the overall evaluation of the characterisation model, the importance of each criterion
and sub-criterion is assessed for the impact category in question. A differentiation between
normal (N) and high (H) importance is applied. Criteria of high importance are criteria which
significantly differentiate the different models from each other and which address key aspects
for the resulting characterisation factors.
For some of the sub-criteria, it is relevant to define an exclusion threshold as a required
minimum performance. Whenever a characterisation model fails to pass such an exclusion
threshold, the subsequent analysis of that characterisation model is not performed.
2.2.4 Development of criteria for the evaluation of endpoint
models
Discussions on midpoint vs. endpoint modelling started under the umbrella of the US EPA
and UNEP and continued within the Life Cycle Initiative 5 , a joint project between UNEP and
SETAC, where a comprehensive LCA framework has been proposed to combine midpointoriented
and damage-oriented approaches in a common and consistent framework. The
present chapter focuses on the assessment of midpoint and endpoint categories for a set of
LCIA impact categories, building on the latest outcomes of the Life Cycle Initiative on this
issue 6 .
The general criteria in Chapter 2 also apply for the evaluation of characterisation models
linking midpoint impacts to impacts on the Areas of Protection (endpoint characterisation
models). In addition, to ensure environmental relevance across the different midpoint impact
indicators and a consistent and common approach to midpoint-damage modelling, the
following guidelines specific to midpoint-damage modelling shall be considered in the
development of specific criteria for endpoints (compare with Margni et al., 2008):
The goal of damage modelling is to aid in understanding and interpreting midpoints. It
aims to make results in different midpoint categories cross-comparable within Areas of
Protection using, as far as possible, natural science approaches, and not necessarily to
arrive at a single score. It can then replace or support weighting practices in the
midpoint approaches. In some cases, a scientific approach for midpoint factors which
are truly cross-comparable even within an impact category, does not exist. In such
cases, endpoint approaches will be necessary, which should avoid implicit value
judgements.
All modelling (midpoint and endpoint) should ideally be properly documented on
uncertainty and reliability. The choice to go to the damage/endpoint level is to be
maintained, as is to eventually come to different recommendations depending on the
context/application and to increase transparency. In this sense the framework should
enable both (midpoint and damage) in a consistent way.
5 See Bare et al. 1999, 2000 and Jolliet et al., 2004
6 See Margni et al., 2008
2 Development and Application of the Criteria for Evaluation 12