Page 72 - Materials Chemistry, Second Edition

L1644_C02.fm Page 49 Tuesday, October 21, 2003 3:07 PM

Trees Iron Ore Oil Oil

Wood Iron Foam Fabric

Chair
Manufacturing

Electricity Wood Wastes Chair
FIGURE 2.5 Simplified process flow diagram for chair manufacturing.

time-consuming task in an LCA study; establishing qualitative and quantitative
information concerning the process and its elementary flows requires a lot of work.
The data collection can build on data from different kinds of data sources, which
can be divided into four main categories, as presented in Table 2.2.
When using data from an electronic database or literature, it is important to
ensure that they concern the relevant processes and come from secure sources, and
are updated and in accordance with the goal and the system range previously
established.
Experience with data collection shows large differences in the availability of
input and output data. Input data are the most readily available because energy and
raw material consumption are registered by the companies. Also, for cases of com-
panies with uniform production profiles, energy consumption per product unit can
be calculated on the basis of the company’s total energy consumption. For nonuni-
form profiles, energy consumption must be estimated for each individual process.
Output data, with the exception of the main product and sometimes some by-
products, are difficult to find. This difficulty is due in many cases to the absence of
control registers of all releases, and the impossibility of allocating the existing data
to the individual product. This feature is typically dependent on the size of the
company in the study. Nevertheless, as recommended by Hauschild and Wenzel

TABLE 2.2
Various Types of Data Sources
Data sources

Electronic databases Several databases provided by commercial and
public software and Internet sources on LCA
Literature data Scientific papers, public reports and existing
LCA studies
Unreported data Provided by companies, laboratories, authorities
and correlated sources
Measurements and/or computations Calculated or estimated where data are
nonexistent or should be improved
Adapted from Hauschild and Wenzel (1998).

© 2004 CRC Press LLC