Monetary evaluation in LCA of WM: everything engineers always wanted to know about it (but were afraid to ask)

For the most part, the LCA community considers economic indicators as an additional dimension to assess, aside from the environmental and social ones. For the task of integrating LCA with life-cycle costing (LCC) and social life-cycle analysis (S-LCA), the favour of researchers and practitioners is mostly given to multicriteria decision analysis (MCDA). Monetary valuation is still regarded with some suspicion despite the publication of the ISO 14008 standards favouring the development of monetisation techniques in the typical fields of application of LCA. We argue that, on the one hand, this attitude may descend from a fundamental misunderstanding of the contribution of the conceptual roots of monetary valuation. On the other hand, monetary valuation has shortcomings that should be acknowledged, that depend both on technical reasons and on more substantial theoretical ones. Despite these shortcomings, monetary valuation has a great merit: that of reversing the burden of proof on those who affirm the desirability of certain actions beyond what seems economically efficient. We exemplify this reasoning using the optimal rate of recycling as a case study.