Encyclopedia of Environmental Science and Engineering, Volume I and II

506 INDUSTRIAL ECOLOGY

(ISO) included LCA in its ISO 14000 environmental certi-

fication process. As a result of these efforts, an overall LCA

framework and a well-defined inventory methodology have

been created.

LCA consists of three phases (Udo de Haes, 2002):

Goal and scope definition: A phase to set the pur-

poses and boundaries of a study, such as geographic

scope, impact categories, chemicals of concern, and

data-availability issues

Life-cycle inventory analysis: The most objective and

time-consuming process, in which the energy, water,

and natural resources used to extract, produce, and

distribute the product, and the resulting air emissions,

water effluents, and solid wastes, are quantified

Life-cycle impact assessment: An evaluation of the

ecological, human-health, and other effects of the

environmental loadings identified in the inventory

These three phases are usually being followed by an inter-

pretation phase in which the results from the above pro-

cesses are tracked and possibilities for improvement are

discussed.

Data availability and uncertainty are continuing concerns

of LCA, as are the time and expense required. As a result,

there have been efforts to streamline, or simplify, LCA to

make it more feasible while retaining its key features (e.g.,

Curran, 1996).

Input-Output Analysis

IOA is a technique of quantitative economics intro-

duced by Leontief in 1936 (Leontief et al., 1983, p. 20;

Polenske, 2004). In this approach, an input-output table

is constructed to provide a systematic picture of the flow

of goods and services among all producing and consum-

ing sectors of an economy. IOA also registers the flow of

goods and services into and out of a given region. The

mathematical structure of the basic input-output models

is simple:

x  Ax 
 y (2)

where x is a vector of outputs of industrial sectors and y is a

vector of deliveries by the industries to final demand. A is a

square matrix of input-output coefficients; each element a ij

represents the amount of sector i ’s output purchased by sector

j per unit of j ’s output (Leontief et al., 1983, p. 23).

IOA approaches material cycles by replacing the mon-

etary flows with material ones. Its initial demonstration was

a projection of U.S. nonfuel-minerals scenarios, completed

by the creator of the input-output method in the early 1980s

(Leontief et al., 1983, pp. 33–205). The analogous approach

for physical flows is termed a “physical input-output table”

(PIOT). It is the product of the efforts of scholars from vari-

ous disciplines between the 1970s and 1990s, and has been

applied to establish the material accounting system of several

TABLE 1

Types of material-flow-related analysis

Type of analysis A

ab c

Objects of

primary interests

Specific environmental problems related to certain impacts per unit flow of:

substances materials products

e.g., Cd, Cl, Pb, Zn, Hg,

N, P, C, CO 2 , CFC

e.g., wooden products, energy

carriers, excavation, biomass,

plastics

e.g., diapers, batteries, cars

Within certain firms, sectors, regions

B

ab c

Problems of environmental concern related to the throughput of:

firms sectors regions

e.g., single plants, medium

and large companies

e.g., production sectors, chemical

industry, construction

e.g., total or main

throughput, mass flow

balance, total material

requirement

associated with substances, materials, products

Source: Bringezu and Moriguchi, 2002. (With permission)

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