How old are fibers in paper for recycling and what is their life expectancy? A contribution to the life cycle assessment of wood fiber-based products

Mean fiber age (i.e., the mean number of production cycles that fibers in a given paper material have undergone so far) can be calculated theoretically on the basis of mass flows in a given paper recycling loop. Mean fiber age distributions can be calculated in multiple, connected recycling loop systems, which are typical of countries and regions with high recovered paper utilization and recycling rates. The calculation uses a graph theory approach. The same approach shows there is a second important value that highlights another aspect of the circular economy – the number of future material uses. This value quantifies how often the fibers in a given paper product will be used on average till their end of life. Put simply, the fiber age describes the past and the number of future material uses describes the future of the fibers in a paper or board product. Calculated results for the European region are presented and compared for fiber age and number of future material uses. Both values add up to a total number of material uses and should be used together.