PERSPECTIVES IN LIFE CYCLE
IMPACT ASSESSMENT
A STRUCTURED APPROACH TO
COMBINE MODELS OF THE TECHNOSPHERE, ECOSPHERE AND VALUESPHERE
PATRICK HOFSTETTER
ABSTRACT
Environmental Life Cycle Assessment (LCA) is a tool used to compare the
environmental impacts along the life cycle of products. It thus supports
the design of products which cause less harm to the environment. ISO distinguishes
between four phases within LCA: the goal and scope definition, the inventory
analysis, the impact assessment (LCIA), and the interpretation. The impact
assessment phase as well as some aspects of the interpretation phase are
the subject of this book.
LCA is a young tool which is still under development. In the course
of its international standardisation ,two main problems have been identified:
(1) LCA is full of subjectivity and does not properly separate objective
from subjective elements, and (2) the impact assessment records phantoms
rather than actual damages. This book suggests a new framework for LCA
designed to master these two problems.
The new structure represents a radical departure from past attempts
in LCA methodology development to distinguish clearly between so-called
objective and subjective elements and to assign them to distinct process
phases. It builds instead on the acceptance of the view that LCA is the
art of modelling and combineing the valuesphere, the ecosphere, and the
technosphere. This basic structure is then particularised with the use
and combination of elements developed independently in many different research
fields in the natural, social, and medical sciences. The book's focus is
on problems rather than disciplinary research questions that highlights
the interface between natural and social sciences. The careful review and
combination of these existing elements in the new structure results in
a partly operationalised framework organised around a number of hypotheses.
These have a high level of explanatory power for past developments and
new trends and seem to offer a fruitful base for further validation.
The book offers concrete and pragmatic operationalisations of many
of the hypotheses demonstrating that a consistent realisation of the framework
is feasible in principle even though central elements remain in the status
of hypotheses. The following elements are fully worked out in this
book:
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The valuesphere is explicitly accepted as a sphere of its own and not seen
as making up the undesired subjective elements which somehow have to be
circumvented. The valuesphere therefore has to be modelled as such. An
evaluation of models which characterise societal groups and their world
views revealed that Cultural Theory serves well to model the valuesphere.
Cultural Theory claims: (i) that people can be classified according to
the degree that they organise themselves in groups and the degree to which
individual lives are circumscribed by externally imposed prescriptions;
(ii) that cultural biases can be understood as shared values and beliefs;
and (iii) that there are five viable ways of life which combine different
social relations and cultural biases. This theory serves to model value
choices inherent in LCA in a way that is compatible with the values and
beliefs of archetypes identified as viable ways of life. Only three of
the five archetypes (hierarchists, individualists, and egalitarians) are
considered because they are the only ones that actively take part in decision
making. Consequently, this book offers not just one but three assessment
systems. Each one is compatible with one of three active perspectives.
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The ecosphere is modelled by three submodels: a model for the known damage,
a model for the unknown damage, and a model for the manageability of the
damage.
-The model of the known damage includes causal effects by environmental
interventions on safeguard subjects representing the environment. The model
is operationalised for carcinogenic and respiratory effects in human beings
and includes fate, exposure, effect, and damage analyses for a selection
of more than 150 substances contributing to these effects. Damage to human
health is measured in terms of disability adjusted life years (DALYs),
a unit that is already used internationally and which is adapted here for
use in LCA. The best estimate for the steady-state health damages in Europe
due to actual emissions of carcinogenic substances resulted in a share
of about 3% compared to all health damages (including all risk factors)
and is dominated by the heavy metals and persistent organics. The same
share for substances causing respiratory effects is estimated to be about
6% and is fully dominated by primary and secondary particles.
-The model of the unknown damage acknowledges that little is known
so far on causal relationships in a system which is best characterised
as overcomplex. The proxy index combines bioconcentration factors and world-wide
emissions in order to consider the accumulating behaviour of, and the relative
knowledge that is available on, a substance.
-The manageability of damage considers the dynamic aspects of the damages
and is quantified by indicators for the ease of damage reduction, the excess
of target damage, and the success of regulation.
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The combination of the three spheres is relatively easy because the outcome
of the inventory analysis, i.e., the model of the technosphere, is already
well known and presented in so-called inventory tables which are the direct
input for the three submodels of the ecosphere. The ecosphere's submodels
are chosen in such a way that their outcomes fulfil the requirements from
all those archetypes considered to be active decision makers and that are
characterised in the valuesphere. The interface between the valuesphere
and the technosphere is described on the basis of two examples.
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A graphical dominance analysis is presented in order to improve the interpretation
of the modelling results. Decisive rankings between alternatives can be
made thanks to this new tool with as little weighting as necessary. This
avoids the need to offer in all cases a full aggregation with a fixed weighting
set which is the direction taken by several proposals to valuate environmental
impacts in LCA.
This ambitious framework for LCA is partly operationalised and partly complemented
with suggestions for a pragmatic operationalisation of those elements left
inoperable. The framework is open for adjustments and the elements can
be made operable by use of adequate models from the different disciplines
concerned. A fourfold meaning of perspectives is worked out in this book:
the LCA perspective of the world addressing the life-cycle view and its
implications; the perspective of understanding LCA as a model of three
spheres; the cultural perspectives leading to models that depend on world
views; and finally the perspective of future developments supported by
the openness of the framework.
Keywords: Life Cycle Assessment, impact assessment, Cultural Theory,
damage assessment, unknown damage, manageability, carcinogenic effects,
respiratory effects, graphical dominance analysis
Deutsche
Zusammenfassung
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