[en] The choice between several alternatives is a process by which the advantages of each of the options are analyzed, and it ends up deciding which one is considered the best. When the characteristics of the alternatives are known, the selection criteria are few and defined, and the consequences of the choice made are trivial, the process is simple. When, on the other hand, the characteristics of the alternatives are not known in detail, or the criteria involved are many, or the consequences are importants, the decision-making procedure becomes complex, and it is not easy to weigh the selection criteria in an intuitive way. Complexity increases even more when there is variability or uncertainty when estimating the parameters of the decision model. In addition to uncertainty, there may be other problems that hinder decision-making: vagueness, ambiguity, subjectivity or discrepancies. In these cases, it is necessary to use tools that allow us to systematize the problem, and help us to achieve that the chosen alternative actually corresponds to the best of those available. Multi-criteria decision methods have been used for years as powerful tools for solving these types of problems. In this Doctoral Thesis we work with one of these tools, the Integrated Value Model for the Evaluation of Sustainability - MIVES, applying it to the resolution of a specific case. MIVES was originally conceived as a deterministic method. In this Thesis, two methods are presented to solve the problem in situations in which there is uncertainty or other problems mentioned: one based on stochastic simulation, and the other on fuzzy arithmetic. The case study used corresponds to the heating system of a residential building, for which four possible alternatives have been analyzed: individual hydronic heating with radiators and natural gas boiler, the same system as the previous one, but with centralized production, the previous same heating system for production, but distribution by underfloor heating and multi-splits. The evaluation model created includes a total of 22 indicators from the economic, social and environmental areas. The deterministic and the two non-deterministic methods have been applied to this case study, concluding that the order of prevalence of the alternatives studied is: (1) multi-splits; (2) underfloor heating with centralized production; (3) centralized production with radiators; (4) individual production with radiators.

[gl] A elección entre varias alternativas é un proceso mediante o que se analizan as vantaxes de cada unha das opcións, e remátase decidindo a que se considera a mellor. Cando as características das alternativas son coñecidas, os criterios de elección son poucos e definidos, e as consecuencias da elección realizada son triviais, o proceso é sinxelo. Cando, en cambio, non se coñecen en detalle as características das alternativas, ou os criterios que interveñen son moitos, ou as consecuencias teñen consideración, o procedemento decisorio vólvese complexo, e non é fácil ponderar os criterios de elección dunha maneira intuitiva. A complexidade aumenta aínda máis cando existe variabilidade ou incerteza á hora de estimar os parámetros do modelo de decisión. Ademais de incerteza, pode haber outros problemas que dificulten a toma de decisións: imprecisión, ambigüidade, subxectividade ou discrepancias. Nestes casos faise necesario empregar ferramentas que nos permitan sistematizar o problema, e nos axuden a lograr que a alternativa elixida se corresponda en realidade coa mellor das dispoñibles. Os métodos de decisión multicriterio véñense usando hai anos como potentes ferramentas para a resolución deste tipo de problemas. Nesta Tese Doutoral trabállase cunha destas ferramentas, o Modelo Integrado de Valor para a Avaliación da Sostibilidade - MIVES, aplicándoa á resolución dun caso concreto. MIVES concibiuse en principio como unha aplicación determinista. Nesta Tese, preséntanse dous métodos para resolver o problema en situacións nas que existe incerteza ou algún dos problemas aludidos: un se baséase na simulación estocástica, e outro na aritmética difusa. O caso de estudio utilizado corresponde ao sistema de calefacción dun edificio residencial, para o que analizáronse catro posibles alternativas: calefacción individual hidrónica con radiadores e caldeira de gas natural, mesmo sistema ca o anterior pero de produción central, mesmo sistema de produción anterior pero distribución por solo radiante e multi-splits. O modelo de avaliación creado inclúe un total de 22 indicadores dos ámbitos económico, social e ambiental. O método determinista e os dous non deterministas aplicáronse a este caso de estudo, concluíndo que a orde de prelación das alternativas estudiadas é: (1) multi-splits; (2) solo radiante e produción central; (3) produción central con radiadores; (4) produción individual con radiadores.