Chemistry Reference
In-Depth Information
?
Emissions
Materials
Energy
Wastes
Fig. 5.2
The life-cycle of a product or
activity.
Table 5.1
The SETAC and ISO defini-
tions of the four phases within LCA
methodology
SETAC
ISO 14040 series
(1) Goal Definition and Scoping
(1) Goal and Scope Definition (ISO 14041)
(2) Inventory Analysis
(2) Inventory Analysis (ISO 14041)
(3) Impact Assessment
(3) Impact Assessment (ISO 14042)
(4) Improvement Assessment
(4) Interpretation (ISO 14043)
Goal definition and scoping
ous life-cycles after the manufacturing stage. The
scope of such studies is from 'cradle to gate', and they
follow a product from the extraction of raw materi-
als to the factory gate.
One of the most important elements of an LCA
study—
the functional unit
—also is defined in this
phase. The functional unit is a quantitative measure
of the output of products or services that the system
delivers. In comparative studies it is crucial that
the systems are compared on the basis of equivalent
function, i.e. the functional unit. For example,
comparison of different drinks packaging should be
based on their equivalent function, which is to
contain a certain amount of beverage. The functional
unit then is defined as 'the quantity of packaging
necessary to contain a specified volume of
beverage'.
This phase also includes an assessment of the data
quality and establishing the specific data quality
goals. Goal definition and scope are constantly
reviewed and refined during the process of carrying
out an LCA, as additional information on the system
becomes available.
The first and probably most critical phase of an LCA
study is Goal Definition and Scoping. This compo-
nent includes defining the purpose of the study and
its intended use, i.e. whether the study is going to be
used internally by a company for improving the per-
formance of the system or externally, e.g. for mar-
keting or influencing public policy. Scoping explains
what assumptions have been made and why, and
defines the limitations of the study, system and the
system boundaries, including its spatial and tempo-
ral limits.
It must be borne in mind that in LCA the system
boundary should be drawn to encompass all stages
in the life-cycle from extraction of raw materials to
the final disposal. This is referred to as a 'cradle-to-
grave' approach. However, in some cases the scope
of the study will demand a different approach, where
it is not appropriate to include all stages in the life-
cycle. This is most often the case with commodities
for instance, which can have a number of different
uses so that it is not possible to follow their numer-
