This article takes a detailed look at an uncertainty factor in waste management LCA that has not been
widely discussed previously, namely the uncertainty in waste composition. Waste composition is influenced
by many factors; it can vary from year to year, seasonally, and with location, for example. The data
publicly available at a municipal level can be highly aggregated and sometimes incomplete, and performing
composition analysis is technically challenging. Uncertainty is therefore always present in waste
composition. This article performs uncertainty analysis on a systematically modified waste composition
using a constructed waste management system. In addition the environmental impacts of several waste
management strategies are compared when applied to five different cities. We thus discuss the effect of
uncertainty in both accounting LCA and comparative LCA. We found the waste composition to be important
for the total environmental impact of the system, especially for the global warming, nutrient enrichment
and human toxicity via water impact categories.