Page 118 - Materials Chemistry, Second Edition

114 5. Development and applicability of life cycle impact assessment methodologies

et al., 2011). The characteristic factors are used in this kind of transformation. The
computational result can be expressed by a numerical indicator.

In S-LCIA, the characteristic models under the social and economic influencing mecha-
nisms can’t always be operated in mathematics. It may be a logical integration step, and
aggregates words or inventory information into a single concept, and can also merge the
quantitative social and sociometric inventory data into one category. The characteristic model
can also be more complex, which includes the use of additional information (like
performance-related points). According to international conventions or the best practice,
the performance-related points may be set threshold value. It also needs to be transparent
and to be recorded.
There is one important difference between LCA and S-LCA. In LCA, the characteristic
model is the product of the inventory data and the characteristic factors are defined on the
basis of environmental science; but when evaluating society (qualitatively or quantification-
ally), a points system, on the basis of the performance-related points, is needed to help eval-
uate meaning of the inventory data, which is an estimate about impact. Contrary to LCA, the
grading and weighting steps of S-LCA may not proceed in characterization step, and the
attention is needed that the model and standard of defining characteristic factors, which must
be defined and transparent well, in S-LCIA stage. The same goes for the grading and
weighting system.

5.4.3.3 Inventory analysis
The inventory analysis is a phase to process to collect data, build models and gain social life
cycle inventory in a S-LCA. In this phase, the related data will be collected to prioritize data,
evaluate hot spots, evaluate fixed-point, and assess impact (characterization). In this phase,
the data needs to be verified and the system boundary should be confirmed. Then, the data
will be related to functional units and integrated according to different situations.
On the basis of the research target and the definition of scope, the inventory analysis can be
started initially. The specific steps can be shown as follows (Benoıˆt et al., 2009):
(1) data collection (filter, prioritize and evaluate hot spot);
(2) data collection preparation;
(3) collect the key data;
(4) characterize;
(5) data validation;
(6) association of data and unit process;
(7) extract the boundary system; and
(8) data consolidation.
The most time-consuming stage is to collect the specific data, which will be used to verify
how the organization connects with the production in social and economic aspects. Under
ideal conditions, the fixed-point analysis can be finished by accessing the organization, which
supplies meaningful input in product process unit. However, though the supply chain is lim-
ited, the cost of data collection will be too high and it will also take too much time, which will
be impractical. So, it has important meaning for an S-LCA to prioritize the data and predict
the significance in the whole process of production.