Page 44 - Materials Chemistry, Second Edition

28 2 Goal and Scope Definition

examples, see Section 1.3.2, Table 1.1) are feasible – among others, those preparing
environmental policy measures. Since the international standards are quite flexible
with regard to the details of the conduct of an LCA (this is valid in particular for
the phase of life cycle impact assessment, LCIA; see Chapter 4), first an adaptation
of the general methodology to the problem in question must be specified. This is
achieved by defining the scope of the study.

2.2
Scope
2.2.1
Product System

First, the examined product system or, in case of comparative LCAs product
systems must be clearly described. This includes, above all, the functions of the
systems as basis for the definition of the functional unit (fU) (see Section 2.2.5).
The description should be brief, but as precise as possible in this early phase.
A product system is best described in a system flow chart. Figure 2.1 shows a
simplified system flow chart of a poly(vinyl chloride) (PVC) window.
In a system flow chart, unit processes and their interrelations are usually
represented by boxes. The entire, often very complex, pattern reminds of a tree and
is therefore often called product tree. Since an essentially linear system definition
is aimed at, branches occur only at the boxes (by several inputs with pre-chains

System boundary
Oil production Iron ore mining Coal mining
and transport and transport and transport
Production PVC Production
sheet steel
Extrusion
Punching, deep-drawing
Screws
Cutting to length
Cutting to length
Teflon foil
Setting in and screwing steel profile
Welding PVC profile Fittings
PVC-lip seal
Assembly window
glass
Installation
Fittings
seals
Demounting use
Material recycling Landfill
Thermal recovery

Figure 2.1 Simplified flow chart of the product system PVC window.