Errors in Conventional and Input‐Output—based Life—Cycle Inventories

Conventional process‐analysis‐type techniques for compiling life‐cycle inventories suffer from a truncation error, which is caused by the omission of resource requirements or pollutant releases of higher‐order upstream stages of the production process. The magnitude of this truncation error varies with the type of product or process considered, but can be on the order of 50%. One way to avoid such significant errors is to incorporate input‐output analysis into the assessment framework, resulting in a hybrid life‐cycle inventory method. Using Monte‐Carlo simulations, it can be shown that uncertainties of input‐output– based life‐cycle assessments are often lower than truncation errors in even extensive, third‐order process analyses.