Lifecycle analysis - Carrying out the inventory

Life Cycle Assessment (LCA) is a compilation and evaluation of inputs and outputs, and a representation of the potential environmental impacts of a system performing one (or more) function(s), along its entire life cycle. In other words, it's a tool for assessing the potential environmental impacts of all the processes involved in one (or more) product(s), service(s) or process(es) fulfilling one (or more) function(s).

The LCA methodological framework was standardized between 1997 and 2000 by the ISO 14040 series of standards to and comprises four stages:

• defining the objectives and scope of the study ;

• Life cycle inventory (LCI) analysis;

• Life cycle environmental impact assessment (LCIA, which includes classification, characterization and overall assessment of impacts);

• interpretation of results.

Let's take the case of the function "printing A4 pages" performed by the product "laser printer toner". To carry out an LCA, it is first necessary to define the objectives of the study in relation to this function: for example, to compare different brands of toner, or to evaluate the performance of new components and manufacturing processes. Next, the function must be quantified using a functional unit: for example, "printing 1,000 pages with a coverage rate of 5%". The associated life cycle can include all the processes involved in producing, using, dismantling and disposing of the toner ("cradle-to-grave" approach). As a study of the entire life cycle would require too much time and resources, we generally limit ourselves to one part (the product system), identified according to the objectives of the study. The inventory analysis consists in assessing the quantities of materials and energy entering and leaving the product system, generally for different scenarios, depending on the objectives set. In order to be able to interpret the inventory results, these quantities are transformed into potential environmental impacts relative to all impact categories, taking into account the state of knowledge ( [G 5 605]...