Methods for Life Cycle Inventory of a product

Methods for Life Cycle Inventory (LCI) compilation are reviewed and compared. In total, six methods are distinguished. They are LCI computation using process flow diagram; matrix expression of product system; input–output (IO) based LCI; and three different forms of hybrid analysis: the tiered hybrid analysis, the IO-based hybrid analysis, and the integrated hybrid analysis. Theory and principles of these methods are presented using a numerical example, and evaluated with regard to data requirements, uncertainty of source data, upstream system boundary, technological system boundary, geographical system boundary, available analytical tools, time and labour intensity, simplicity of application, required computational tools and available software tools. Compliance of these methods to ISO standards is discussed. Finally, conclusions are drawn, combined with a view on the future outlook of these inventory building methods.