A semantic study of the Emergy Sustainability Index in the hybrid lifecycle-emergy framework

•Different versions of the Emergy Sustainability Index (ESI) are compared.•A specific algorithm is developed to compute the ESI's lifecycle-oriented version.•Although operational, the definition of foreground inputs needs further discussion.•Sensitivity analysis can identify specific potential actions to increase the ESI.•ESI can be efficiently increased by influencing suppliers’ environmental policy.