Page 20 - Materials Chemistry, Second Edition

4 1 Introduction

1.1.4
LCA as System Analysis
LCA is based on a simplified system analysis. The simplification consists of an
extensive linearisation (see system boundaries and cut-off criteria in Section 2.2).
Interconnections of parts of the life cycle of a product that always exist in reality
lead to extremely complex relationships in the modelling, which are most difficult
to handle. There are, nevertheless, possibilities to handle the formation of loops
and other deviations from the linear structure, for example, by an iterative approach
or matrix calculus. 13)

Example

LCA deals with the comparison of product systems, and not of products. This
means the following:

Within the product segment ‘towel dispenser’, for example, paper towels and
cotton rolls are two possible variations. The cotton roll needs to be cleaned
to fulfil its function. This means, the cleansing process (detergent, water
and energy consumption) is part of the product system and must surely be
considered. In addition, washing machines must be applied for cleaning.
Has the production of washing machines to be considered as well?
Their production requires, for example, steel. Steel is made from iron ore that
needs to be transported, and so on. It is obvious that limitations need to
be set, because every small product is linked to the entire industrial system.
On the other hand, nothing essential shall be omitted.

System analysis and the meaningful selection and definition of system bound-
aries are therefore important and labour-intensive tasks within every LCA.
The main advantage of the life-cycle approach ‘from cradle to grave’ lies in its
ability to easily detect the shifting of environmental burdens, the so-called trade-offs,
which may, for example, occur owing to material substitutions. Therefore, it is of
no use to seemingly solve an environmental problem if, later, in different life cycle
stages or environmental media, the same or additional problems occur. The same
applies when an unreasonable energy or resource consumption may be connected
with the substitution. These kind of activities do not solve the problem at its
base.
It is not arguable that in rare cases, especially those of health hazards (e.g. sub-
stitution of hazardous substances), such suboptimal decisions may be applicable.

13) Heijungs (1997) and Heijungs and Suh (2002).