This study investigates the possibility of using municipal solid waste incineration fly ash as a supplementary cementitious material to replace part of the clinker in cement. Life cycle assessment has shown that the partial replacement of clinker with blast furnace slag (CEM III) reduces cement’s global warming potential by ~30%, while replacing clinker with fly ash reduces it by up to 55%. When using CEM III as the control binder in cement in which 55 wt% of the clinker was replaced with hydrothermally treated fly ash, the flexural strength decreased by ~60% and the compressive strength by ~65%. When the fly ash was mixed with calcined and vitrified demolition materials, flexural strength decreased by ~30% and compressive strength by ~50%. The hardening of the hydraulic binders fixed the heavy metals in the municipal solid waste incineration fly ash.

Education for sustainable development (ESD) is one of the great challenges that university faculties have to face. Therefore, a multidisciplinary team from the faculty of Engineering of Gipuzkoa (EIG) at the University of the Basque Country (UPV/EHU) has developed pedagogical approaches to apply in construction degrees, namely Civil Engineering and Technical Architecture. Pedagogical tools, such as problem-based learning (PBL) or research-based learning (RBL), and environmental tools, such as the life cycle assessment (LCA) and computational thinking (CT), have been used; in doing so, they acquire a sustainable approach to work “soft-skills” competencies into sustainability. For example, research-based tools have helped to revalorize waste both outside and inside the university; they have contributed to more sustainable industrial processes, collaborative research projects, and participation in conferences and scientific publications. Based on academic results, the designed tools are appropriate for teaching in Technical Architecture and Civil Engineering degrees; however, to demonstrate their potential in terms of sustainable education, holistic rubrics based on in-depth quantitative educational research are required. Thus, to analyze the ability of the students to incorporate sustainability principles in their work, the multidisciplinary team presenting this paper plans to collaborate with psychologists and sociologists within the framework of the Bizia-Lab program of the UPV/EHU.

The intervention on historic buildings through building energy retrofitting has become one of the current challenges of improving energy efficiency. Nonetheless, this building typology presents certain complexities. Among them, one of the most relevant is the protection on their façades due to the historical and/or artistic values of a given façade and, therefore, the addition of external thermal insulation is restricted. However, at the same time, in several of those buildings indoor surfaces do not present that architectural value, and then internal thermal insulation becomes a promising strategy for improving their thermal performance. Nevertheless, its application must be carefully evaluated to avoid possible pathologies caused by moisture problems. This paper aims to identify constructive solutions for interior insulation of walls free from moisture problems. For this purpose, a comprehensive analysis of a series of constructive solutions based on internal insulation has been carried out through hygrothermal simulations. The results show how the application of water-repellent impregnation becomes essential to guaranteeing the integrity of the envelope. In addition, the combination of insulations with or without inner membranes, such as smart vapor retarders or vapor diffusion barriers, has been evaluated detecting the solutions that best fit the objective. Finally, taking advantage of the great potential of 2D simulation tools, the post-processing of the data has been performed to apply the wood decay model, and thus assess the behavior of a very conflictive point in this type of intervention, i.e., the wooden beam-ends. The results in this critical point have shown how the application of the proposed constructive solutions becomes essential to guarantee the integrity of the element and how the application of traditional solutions could lead to a hazard that must be avoided.

Airtightness is a major issue in architectural design and it has a significant impact on the energy performance of buildings. Moreover, the energy behaviour of built heritage is due, to its singular characteristics, still a great unknown. The aim of this study is to establish a better knowledge of the airtightness of historical buildings, based on an in depth field study using blower-door tests. A set of 37 enclosures were analyzed inside eight buildings located in historical areas of a Spanish city with a significant built heritage. They were constructed between 1882 and 1919 and include diverse construction typologies applied for many building uses such as residential, cultural, educational, administrative and emblematic. The results indicate lower values compared to other previous airtightness studies of historical buildings. The average air change rate was found to be n₅₀ = 9.03 h⁻¹ and the airtightness of the enclosures presented a wide range of between 0.68 and 37.12 h⁻¹. Three main levels of airtightness were identified with two thirds of the tested samples belonging to the intermediate level between 3–20 h⁻¹. To conclude, several correlations have been developed which provide a method to estimate air leakage and could serve as a basis for energy performance studies of these kinds of building.