Buildings are responsible for 40% of the overall final energy consumption in the European Union. On the other hand, the construction, energy, and industry sectors generate around 50% of the waste produced in Europe, out of which a third part is construction and demolition waste (CDW). In recent years, many research works have been carried out to analyze the viability of incorporating waste, especially CDW, as a substitute for traditional raw materials with great environmental impact. However, most of the studies found cover only the mechanical characterization of the compound, and there are very few that analyze these materials in specific building applications. This research work evaluates the energy efficiency potential of recycled materials with CDW. After an exhaustive analysis of the main existing recycled materials, an energetic evaluation of several construction solutions is carried out, as well as a comparison with traditional solutions. The findings show that the incorporation of recycled materials in several building construction elements is a success, since it not only reduces the consumption of raw materials, but also reduces the energy consumption of the building. Energy savings using recycled materials can range from 8% in a warm region (such as Seville) up to 13% in cold regions (such as Soria), which are greater in heating than in cooling.

The actions for the preservation of cultural heritage must work on the identity and specificity of the places, paying the utmost attention to the context relationships. The analysis of these elements is fundamental to the recognition of the intrinsic “value” of the building, of the cultural, architectural, and landscape type and of the “value relations” that the building holds with the surrounding context of the social and economic but, above all, cultural and identity type. The methodological approaches defined by the ICOMOS Document of Madrid–New Delhi recognize the identification of the cultural value as a fundamental passage for the promotion of the 20th-century heritage. The contribution analyzes the design process developed by applying the ICOMOS methodology for the preservation of the cultural value of a building complex in Pozzuoli dating back to the early 1900s. The evolutionary history of the different volumes and the configuration of the “modern ruins” give rise to prospective relationships with the local reality that today assume a stronger identity value than that connected to the original project. The different construction techniques used and the state of conservation of the buildings lead to the identifying of different elements of value and, consequently, to the elaborating different design choices.