Allocation of environmental burdens in co-product systems: Process and product-related burdens (Part 2)

  • Adisa Azapagic
  • Roland Clift
LCA methodology


ISO 14041 requires that allocation by physical causality must reflect the quantitative changes in product outputs or functions and will not necessarily be in proportion to simple physical measure such as mass. This paper examines the instances where physical causality can be represented by mass. However, it also goes further than ISO to demonstrate that the type of causality in the system is not necessarily always the same and can change depending on the way the system is operated. Whole system modelling and the marginal allocation approach are used to identify the correct type of causality for different operating states of the system and the corresponding changes in the environmenta burdens. This is generally not possible with the other allocation methods, also examined in this paper. Both process- and product-related burdens are considered and the approach is illustrated by a reference to an existing system producing five boron co-products.


Allocation boron environmental impacts LCA Life Cycle Assessment linear programming marginal values system analysis 

Copyright information

© Ecomed Publishers 1999

Authors and Affiliations

  1. 1.School of Engineering in the EnvironmentUniversity of SurreyGuildford, SurreyUK

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