Reliability of LCI considering the uncertainties of energy consumptions in input–output analyses

The dispersion of input-coefficients in input-output (I-O) tables and the effect on LCA results are evaluated, utilizing the data for compiling the I-O tables. CO2 emission intensity and its variance with each commodity and service categorized in the I-O tables are estimated and applied to the LCA of a specific passenger car. Calculated results show that coefficients of variation (CV) of CO2-emission intensity are about 0.8 for the intermediate commodities which are frequently assessed in LCA. CO2 emissions induced by the production of the passenger car and the CV of the emissions are estimated at 1.3 Mg-C and 0.14, respectively. The value of CV is smaller than that of the most intermediate commodities since the CV of total emissions decreases as the number of components of the passenger car increases. Although emission intensity itself given by I-O tables has large variance, I-O tables are still useful tools for LCA if the number of components of a product is large enough.