Attributional LCA is a system modelling approach in which exchanges are attributed to the functional unit of a product system by linking and/or partitioning the unit processes of the system according to a normative rule. This definition represents a modification from the UNEP/SETAC 2011 Shonan Database Guidance, where "inputs and outputs" has been replaced with the more precise term "exchanges" to reflect contemporary LCA terminology.
In attributional modelling, the system is constructed by systematically connecting unit processes based on predefined rules that determine how environmental burdens should be distributed or allocated amongst different products and processes. These normative rules provide a standardised framework for assigning environmental impacts, ensuring consistency and comparability across different studies. The approach typically relies on average data and established allocation methods, such as physical or economic relationships, to partition multi-functional processes.
Attributional LCA is particularly suited for describing the environmental performance of existing systems, conducting environmental accounting, and comparing products within similar contexts. It provides a snapshot of environmental impacts based on the actual or average characteristics of the system under study, making it valuable for product labelling, environmental reporting, and identifying environmental hotspots within established supply chains.
