Lifecycle analysis - Assignment problems

Affecter has many synonyms: imputer, attribuer, distribuer, allouer. Generally speaking, it means assigning one's share. Who is responsible for polluting this river? What causes the greenhouse effect? What is the environmental impact of incinerating PVC bottles? All these questions represent problems of assignment. Given the complexity of the natural world and human societies, attributing environmental problems to those truly responsible is the fundamental challenge of environmental analysis, and the prerequisite for any preventive measures. What's more, allocation problems are very general in scope, since they are also encountered in economic and social analyses of systems.

We present here in detail the [1] allocation methods used or envisaged in the field of Life Cycle Assessment (LCA). LCAs are basically problems of assigning environmental impacts to a function, considering all types of environmental impact and all stages of the life cycle, from extraction of natural resources to final processing. This function may be to produce a bottle, to transport an individual from point A to point B, or to properly treat a given waste product. Our societies are highly complex, and all the processes linked to one function often fulfil numerous other functions. Oil, for example, is used to produce many types of product: how much oil production (and associated environmental problems) is linked to the production of unleaded petrol? How much landfill impact do stored batteries have?

Resolving allocation problems is one aspect of the goal definition stage, because in order to allocate, you first need to define the system. However, it is also part of the inventory stage. We define assignment problems as problems of assigning loads to functions. In this article, loads are defined as all flows that have an environmental impact, e.g. energy or transport requirements, consumption of natural resources, emissions of pollutants. The links between loads and impacts are established in other parts of the inventory [29] and above all in the impact assessment stage [30] . The loads considered are environmental, as LCAs are currently limited to these aspects. However, the notion of burdens could be extended to the economic and social fields.

The function assignment considered here often involves distributing the environmental load of a system among all the functions performed by that system. However, in some cases, the assignment involves modifying the system at some point.

There is no generally accepted allocation method. As the choices made are...