The linking algorithm implements a system model, which is the set of rules and assumptions that include (but are not limited to) how to construct markets in time and space, handle multioutput processes, allocate credit for recyclable materials, etc.
Many system models are currently used in life cycle assessment, environmental product declarations, and footprinting.
ecoinvent publishes three versions, each with its system model: Allocation Cut-Off by Classification; Substitution, Consequential, Long-Term, and Allocation at the Point of Substitution (APOS).
However, for the general community, examining all the explicit and unspoken assumptions and choices that each system model includes can be difficult. Intermediate steps of the linking are also not available.
The Ocelot project aims to provide a new approach to this problem through an open-source implementation of a linking framework.
Initially, we will implement the cut-off and long-term consequential system models in ecoinvent 3.2. Thanks to the structure of Ocelot, users will also be able to make minor modifications to existing models or, with more extensive efforts, even create their own system models. The project’s output is a set of spold2 files, which can be read by software and used to conduct an LCA.
As the importance of LCA continues to grow, the scrutiny and pressure on the scientific basis of LCA will increase.
Providing more transparent and easily modifiable linking algorithms will allow the Ocelot team and the research community to carry out the systematic tests needed to examine the robustness of the various system models, including isolating the effects of individual choices, the impact of different assumptions, and how appropriate certain assumptions are for multiple sectors of the economy.