Nowadays there is a growing interest and need to implement the circular economy model (CE), which is based on keeping resources in circulation as long as possible. The transition towards this model has been taking place in recent years and product design is a crucial factor in achieving this. This is due to the fact that the use of many of the technical and biological resources in circulation and their good use depends on this discipline. Product design, in turn, is a creative discipline which needs to be in permanent innovation to satisfy the new needs that emerge in society. Within all the stages that product design encompasses, it is in the conceptual design stage where the creative activity is carried out and, therefore, the most flexible stage in which changes and new characteristics, such as circularity, can be easily introduced in the products. In order to evaluate the conceptual proposals raised during this design stage, it is necessary to have metrics and evaluation tools that, in an objective way, analyse whether the proposals meet all the requirements and are suitable for further development. These evaluation metrics must be adequate for the conceptual stage in which the final product has not yet been developed and, therefore, the more specific details of the product are not yet available.Gracias a Carlos García y a Carlos 'Mates' por vuestra ayuda con alguna de las partes de la tesis, por ayudarme a mejorarla. Gracias a los dos por haberme aplanado un poco el camino.Thanks to all the people from Universidade de Aveiro that have made my research stay there more comfortable and especially to João Sampaio and Ana Afonso for hosting me there and for your help with the planning and setting up of the workshop. Muito obrigada. I hope to be back in Portugal soon and closing the stay as it deserves. Gracias a Tami, a Raquel and thanks Paulo por hacerme sentir como en casa en Aveiro.Thanks also to all the KATCH_e people from Portugal, Austria, Denmark and Spain for everything that I have learned from you working on the project these years. And also, thanks for the good moments, laughs and parties during the transnational meetings!! I hope we will meet again somewhere, somehow.Gracias a todas las personas con las que he compartido algún momento de descanso, de ir a comer o tomar un café (compañeros del departamento y de otros, doctorandos, etc.). También gracias a las personas con las que he compartido algún viaje a Valencia.Gracias a todos los 'Cantineros' (aka 'Pelea de Perros') por los momentos divertidos que hemos pasado juntos. Y gracias a las personas con las que comparto mi día a día en la UJI. XIIRaúl, en media hora hemos quedado para tomar un café, quería tener esto acabado antes y todavía no sé qué poner aquí, es muy difícil resumirlo en unas líneas. Gracias por tu amistad, por tu compañía, por levantarme el ánimo cuando lo he necesitado y por ayudarme siempre. Sin olvidarme de las veces que me has salvado la vida tecnológicamente, sin ti parte de esta tesis no existiría, literalmente; al menos no tal ...