Page 38 - Materials Chemistry, Second Edition

20 A. Bjørn et al.

when the price on oil was fluctuating or high, energy use was the focus of early
studies. Public concerns also shifted with respect to emissions, which in some
periods were deemed to be sufficiently controlled by regulation and voluntary
measures by industry, but at other times considered very problematic. Early impact
assessment methods tended to represent impacts from emissions in the form of
dilution volumes of air or water needed to dilute the emissions to safe levels, or
below regulatory thresholds [e.g. the Swiss Ecopoint method from the 1980s (Ahbe
et al. 1990)].
During the 1990s many impact assessment methods evolved, and the ambition
has since then been to quantify all relevant environmental impacts, independent of
shifting public concerns, with the goal of avoiding burden shifting. The first impact
assessment methodology to cover a comprehensive set of midpoint impact cate-
gories, as we know them today, was CML92 (Heijungs et al. 1992). It was released
in 1992 by the Institute of Environmental Sciences at Leiden University in the
Netherlands. The Swedish EPS method (Steen 1999a, b) looking at the damages
caused took a different approach focusing on the damages to ecosystems and human
health, rather than midpoint impacts, an approach that was followed by the Dutch
Eco-indicator 99 methodology released in 1999 with a more science-based
approach to the damage modelling (Goedkoop and Spriensma 2000). The early
1990s also saw the birth of a number of life cycle inventory databases managed by
different institutes and organisations and covering different industrial sectors. Due
to differences in data standards and quality, the resource uses and emissions of a
single industrial process could, however, differ substantially in the different data-
bases, but at this point in the development, the focus was on expanding the cov-
erage and for many processes, there were no data at all. This situation was improved
in 2003 with the release of the first ecoinvent database (v 1.01) covering all
industrial sectors and aiming for consistent data standards and quality (ecoinvent
2016).
In parallel to this development in process-based LCA, a “top-down” approach
was developed based on the work of the economist Wassily Leontief on
input-output analysis of economies (Leontief 1970). This “top-down” approach to
constructing an inventory is based on combining the national statistics of the trade
between sectors with information on sector-specific environmental loads to arrive at
an environmentally extended input/output analysis (EEIOA see more in Chap. 14).
Inherent in the discussion of LCI data was also a more fundamental difference in
the perception of the product life cycle and LCA and its potential application. The
attributional perspective aims to quantify the environmental impacts that can be
attributed to the product system based on a mapping of the emission and resource
flows that accompany the product as it moves through its life cycle, applying
representative average data for all processes involved in the life cycle in a book
keeping approach. The consequential perspective is concerned with the potential
consequences of the decision based on the results of the LCA, and involves
modelling of the broader economic system that the decision affects (see Sect. 8.5).