A.J. Sánchez-Garrido, I.J. Navarro , V. Yepes 

Universitat Politècnica de València (SPAIN)
This paper is based on the contents of the postgraduate course "Prediction and optimization models of concrete structures", taught in the Master of Concrete Engineering at the Polytechnic University of Valencia, in which civil engineering students are taught the various techniques of multi-criteria assessment, with a sustainable approach, applied to the optimal design of structures. This allows the student to compare complex aspects with generally contradictory objectives that characterize sustainability under criteria of economic, environmental and social efficiency, among others. Construction companies usually focus on cost optimization during the construction stage of structures that are currently not sufficient to meet the growing social demands of the 21st century world, needing to balance the criteria that support sustainability. The construction sector represents a relevant percentage of the total CO2 emissions, being responsible for a great part of the environmental impacts, which is enough reason for the European Union policies to be more and more oriented to the reduction of these emissions. In this communication, a case study is presented on a research in progress by the teaching body and students who are part of the research team, with the aim of comparing three different construction alternatives (traditional as a reference, prefabricated and technological) in the search for the structural optimum of an urban single-family dwelling from the economic and environmental point of view throughout its life cycle. An analysis of indicators including the production phase, construction, the use and maintenance stage and the end of life has been carried out. The environmental impacts throughout the life cycle of the alternatives have been evaluated on the basis of the Ecoinvent 3.3 environmental database, using the ReCiPe impact assessment methodology. Finally, to evaluate the different alternatives, we have applied the multiple attribute method TOPSIS, based on distance to establish the order of preference by similarity with the ideal solution. Our findings show that the most economical solution in each phase is not the most environmentally efficient. For sustainability-based decision making that does not lead to erroneous results a balance must be sought between all dimensions, including not only monetary aspects in the structure design process.