Multi Criteria analyses, Life Cycle approaches and Delphi Method: a methodological proposal to assess design scenarios. Analisi Multi Criteria, approcci Life Cycle e Delphi Method: una proposta metodologica per valutare scenari di progetto.

The different aspects of sustainability emerge in the choices between projects in the property sector, in the form of impacts - economic, energy, environmental, social, aesthetic - often associated with uncertainty and conflict. Uncertainty is often linked to the measurement of impacts, developed also through the application of specific techniques. Conflict, on the other hand, is linked to difficulties in gaining the consensus of opinions or shared solutions. This is evident in the case of energy retrofitting of existing buildings or new construction operations for energy efficient buildings: in this case, the principles of sustainability have to be compared with global performance requirements, which are implemented in technological-economic scenarios (Directive 2010/31/EU; Directive 2018/844/EU). The Multicriteria approaches, consolidated in the case of decisions in complex and conflictual contexts, and therefore capable of dealing with the many dimensions of sustainability, reveal points of fragility that can be offset by the integration of other approaches. On this basis, the aim of the work is to present a methodological proposal based on the integrated use of Multicriteria Analysis, participatory approaches (Delphi Method) and Life Cycle approaches (Life Cycle Costing -LCC, ISO 15686-5:2008 and Life Cycle Assessment - LCA, ISO 14040:2006). In particular, it proposes an operating mode centred on the Analytic Hierarchy Process - AHP method, with the addition of: on one hand, the LCC and LCA approaches (which can also be combined), to support the identification/selection of criteria and the quantification of parameters of energy-economic-environmental sustainability using measurable indicators; and on the other, the Delphi Method, to support the identification of the preferred scenario(s) on which there can be convergence and correspondence in terms of broad social consensus, based on opinions expressed by panels of experts. Designed for residential properties, widely used in our country, large interventions on public assets or large infrastructure works involving different parties and having different purposes are not excluded from the reasoning. Indeed the recent legislation on Public Works pays special attention to them (in Articles 95 and 96 of Legislative Decree 50/2016 and subsequent updates in DL "Simplifications" 135/2018 and Budget Law 145/2018).