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


Manfred Lenzen Department of Applied Physics, A28 The University of Sydney, N.S.W. 2006, Australia.


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.