Page 127 - Materials Chemistry, Second Edition

3.3 Allocation 111

to a behaviour which benefits the environment. In addition a distribution of loads
and advantages in equal parts is intuitively judged as fair.
A 50 : 50 rule may, however, be less justified if an already flourishing market for
the special secondary raw material of the examined system has been established,
and no stimulation is needed for the provider of used material of A.
The sample study (IFEU, 2006, loc. cit) specifies the following allocation rules
for an OLR in the context of production systems employing polymers.
In a first step the authors consider two independent systems (Figure 3.19).
If system expansion is made, all processes necessary for recycling (e.g. collection,
transportation, sorting, processing) must also be assessed for the system A + B.
Figure 3.20 shows the process pattern for coupled systems with system expansion.
The fU must now refer to the complete system (system A + B).
Allocation rules have to be defined if the fU should refer to the individual systems.
In the sample study the 50 : 50 rule was applied as illustrated in Figure 3.21. The
following segments were defined:
• Recycling: Collection, transport and processing of product A, so that the material
can be inserted into production of B: 50% of the environmental loads connected
with the recycling are added to both systems.
• Waste incineration of A: If after use product A were not prepared as secondary raw
material a waste incineration would follow the production and use phase of A.
Since the environmental loads of the MSWI in system A can only be avoided by
inserting secondary raw material into system B, system A is burdened with 50%
of the MSWI environmental loads (+50%) while system B will be ‘rewarded’ by
50% (−50%) of the MSWI environmental loads as credit entry.
• Polymer production (PP-B): If system B would not take in the secondary raw
material of System A, the polymer for the production of product B would have
to be manufactured from primary raw material. As this primary production of
the polymer was fully assessed in system A (Figure 3.20) for 50% of the polymer
production necessary in system B without recycling a credit entry is inserted into
system A (−50% PP-B) and a debit entry of 50% is inserted into system B (+50%).
For an assessment of system A via 50:50 allocation, system B need not be
completely considered. Therefore less data are required compared to system
expansion. Besides, fUs can be defined separately for A and B which is required
for most goal definitions in LCA.
In the 100:0 allocation, credit entries for secondary material are completely
allocated to the delivering system. This variant is often used to examine the
relevance of results of the allocation method (see Section 3.3.4.4 and Chapter 5).
3.3.4.3 Cut-off Rule
A further important rule (rule 2, cut-off rule) 109) provides exactly defined separation
boundaries between systems A and B, for instance at garbage collection or separa-
tion, and the loads of the two systems are assessed independently. Based on the

109) Not to be confused with cut-off-criteria.