Page 51 - Materials Chemistry, Second Edition

2.2 Scope 35

Europe (North America, Japan, etc. world-wide)? Similar considerations are valid
for agricultural products, services, and so on.
• Even if a relatively close framework is selected, for example, production and sales
in only one country, the geographical system boundary always has extensions
beyond the selected range, because certain raw materials may be missing in the
concerned country and thus have to be imported. Therefore, pollution of the
environment also occurs in the countries of origin and in transportation from
these. For export products, it must be noted that transportation, use and disposal
predominantly take place in other countries. The international distribution of
tasks in the context of progressive globalisation of the world economy (supplier)
must also be considered within the geographical system boundary.
• In LCIA (see Chapter 4), global effects are considered for some impact categories
(e.g. climate change/greenhouse effect, stratospheric ozone depletion), while for
others regional or local effects (e.g. eutrophication potential) are considered. Local
boundaries can, however, be clearly assigned only in rare cases, for instance, if
a special product is manufactured in one factory only. In this case, at least one
point in the life cycle can unambiguously be assigned geographically. Something
similar is valid in agriculture if the farming region can be determined.

Altogether, the definition of the geographical system boundary is straightforward;
it is a question of data availability. Commodities (e.g. metals, mass plastics,
chemicals of very large production volume) often do not reveal their origin; in these
cases, a regional allocation of impacts is difficult, if not impossible (see Chapter 4).

2.2.4
Temporal System Boundary/Time Horizon

The temporal system boundary is more difficult to define than the geographical
boundary.
The minimum specification to the system boundary ‘time’ is a year of reference
or another time period for data acquisition. For long-lived products, a determined
or estimated lifetime or time of use provides a boundary shifted into the future
of the inventory: disposal or re-use will only occur in the future. Accordingly, the
modelling of these life cycle phases is difficult and uncertain.
For long, those problems with time have not been sufficiently considered in LCA
research. 22) This did not play a role as long as predominantly short-lived products
were examined such as packaging. Problems related to time became evident when
LCAs of building materials, buildings and other long-lived products were carried
out:

• How may LCA experts know which (perhaps not even yet invented) methods of
waste disposal will predominate in 50 a, how recycling will be organised, and so
on?

22) Hofstetter (1996) and Held and Kl¨ opffer (2000).