Page 105 - Materials Chemistry, Second Edition

90 A. Bjørn et al.

Identify secondary
functions

For each, can you Yes Perform sub- Cut off the subprocess
sub-divide the multi- division of the providing the
functional process ? process secondary function

No
Integrate the
Can you identify
secondary function
conventional or most Yes Perform system into the system
probable alternative expansion boundaries
way to produce
secondary functions? (displacement/
avoidance of impacts)
No

Can you perform
Perform
meaningful allocation Yes allocation using
using causal physical physical causality
relationship?
No
Partition the
environmental flows
and associated
Perform
Can you perform impacts between the
meaningful allocation Yes allocation using primary and the
representative
using representative physical secondary functions,
physical relationship? parameter and cut off the part
related to the
secondary functions
No
Perform
allocation using
another parameter
(e.g. economic)

Fig. 8.5 ISO hierarchy for solving multifunctionality presented in a decision tree

Subdivision of Unit Process
First choice is to try to solve this problem through increasing the resolution of the
modelling by dividing the multifunctional unit process into minor units to see
whether it is possible in this way to separate the production of the product from the
production of the co-product, and if so exclude the subprocesses that provide the
additional functions from the product system, see Fig. 8.6.
An example of subdivision is when a factory produces two products. Here, the
subdivision approach may lead to the realisation that the factory actually contains a