The leading standards for attributional life cycle assessment, such as the PAS 2050 (BSI 2011) and the WBCSD/WRI product accounting standard (WBCSD/WRI 2011a), allow the use of a method called “substitution” or “system expansion”. This method is used to deal with situations in which a process has more than one useful output or function (e.g. when the process produces two or more co-products), and the emissions associated with just the product studied need to be separated out or identified. This summary paper briefly explains the “substitution” method and why it creates problems for attributional life cycle assessment.
Want to learn more? Download our white paper
Find out about the “substitution” method and why it creates problems for attributional life cycle assessment.