The company Prefabricados Uniblok S.L.U. (Prefabricated Uniblok S.L.U.) is a company from the Ormazabal Group whose main activity is to offer integral solutions to the Medium Voltage Electrical Distribution. Among these activities, they provide turnkey solutions, with transformers substations placed in precast/prefabricated concrete containers/enclosures. Uniblok produces these containers/enclosures in a modern plant located near Madrid, using modern technology. During the last years, Uniblok has tackled improving the sustainability profile of the concrete containers/enclosures, introducing several changes in the mix design and the production procedure on a performance-based requirements scheme that includes long-term durability issues. This paper summarises the improvements achieved due to a joint effort made by Uniblok S.L.U. and the CISDEM (Research Centre for Safety and Durability of Materials and Structures – CSIC – UPM) during the last 6 years. The results obtained confirm that the sustainability profile of the precast/prefabricated concrete containers/enclosures has significantly improved due to research and innovation.