Page 202 - Materials Chemistry, Second Edition

188 LIFE CYCLE ASSESSMENT HANDBOOK

8.2.1 Goal and Scope Definition
Goal and scope definition is the first phase of LCA, and identifies the system
and the audience considered as well as the objectives and insights of inter-
est from the LCA. In defining the scope of the LCA, the system boundary is
indicated, which indicates the region to be analyzed. A definition of scope also
considers the function the system. It is often necessary to define a functional
unit (e.g. one kg of product), to provide a reference for relating the inputs and
outputs. Further details on goal and scope definition are presented elsewhere
(ISO, 1998).

8.2.2 Life Cycle Inventory Analysis

Life cycle inventory (LCI) analysis is the second LCA phase. The first step
in LCI analysis is to identify, for all processes, energy and material inputs
and outputs associated with all flows across and within the system bound-
ary. LCI analysis includes data collection and calculation procedures that
quantify relevant inputs and outputs of the system. Data acquisition often
involves measuring data, collecting data from literature and calculating data
by modelling the process. Due to logistical as well as other barriers, such
as a reluctance by industry to share data considered confidential, obtain-
ing data to be used in LCI is often difficult (Curran, 2000). An inventory
analysis is often an iterative procedure in which, to achieve the goals of
LCA, as data are collected and more is learned about the system, new data
requirements or limitations are identified that necessitate a change in the
data collection procedures. Further details on LCI analysis are presented
elsewhere (ISO, 1997).

8.2.3 Life Cycle Impact Assessment
The third phase of LCA is life cycle impact assessment (LCIA), for which the
aim is to evaluate environmental impacts of the material and energy flows
identified in the inventory analysis. ISO 14042 (ISO, 2000) divides LCIA into
the following steps:

• Classification: This step involves determination of impact cate-
gories, which must be consistent with the goal and scope of the
study. Then, inventory data are assigned to the impact categories,
such as potentials for global warming and ozone depletion.
• Characterization: Inventory data within impact categories are
characterized, first by matching to impact categories and then by
quantifying their contributions to the impact categories. Hence,
the impacts of different environmental flows are assessed using
a common indicator unit for each impact category This calcula-
tion can be done with previously-developed factors or using LCA
software.