Environmental impact assessments over consumer product life cycles can factor in numerous environmental indicators. However, each additional indicator adds to the complexity of the model.

Zoran Steinmann, Radboud University, Nijmegen, The Netherlands, and colleagues evaluated 135 impact indicators for 976 products to arrive at an optimal set, based on their mutual correlations. A set of four indicators covered 92 % of the variance in product rankings, and using six indicators increased this to 92.3 %. The researchers used principal component analysis combined with an optimization algorithm to evaluate resource footprints and midpoint and endpoint indicators measured using 13 standard methods.

The optimal set of indicators covered climate change, ozone depletion, the combined effects of acidification and eutrophication, terrestrial ecotoxicity, marine ecotoxicity, and land use. In comparison, four commonly used resource use indicators (energy, water, land, and materials) accounted for 84 % of the variance in product rankings, and a single indicator (energy demand) accounted for 78.4 %. The optimal set uncovered differences in the impact of products that cannot be distinguished using fewer indicators.

• How Many Environmental Impact Indicators Are Needed in the Evaluation of Product Life Cycles?,
  Zoran J. N. Steinmann, Aafke M. Schipper, Mara Hauck, Mark A. J. Huijbregts,
  Environm. Sci. Technol. 2016.
  DOI: 10.1021/acs.est.5b05179