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Construction involves the use of significant quantities of raw materials and entails high-energy consumption. For the sake of choosing the most appropriate solution that considers environmental and sustainable concepts, tools such as the integrated value model for sustainable assessment (Modelo Integrado de Valor para una Evaluación Sostenible, MIVES) used in Spain, plays a key role in obtaining the best solution. MIVES is a multi-criteria decision-making method based on the value function concept and the seminars delivered by experts. Such tools, in order to show how they may work, require application to case studies. In this paper, two concrete slabs manufactured with differing reinforcements during the construction of the La Canda Tunnels are compared by means of MIVES. The two concrete slabs were reinforced with a conventional steel-mesh and with polyolefin fibres. This research was focussed on the main aspects affecting the construction. That is to say, the environmental, economic, and social factors were assessed by the method, being of special impact the issues related with maintenance of the structure. The results showed that from the point of view of sustainability, the use of polyolefin fibres provided a significant advantage, mainly due to the lower maintenance required.

Throughout the 21st century, urban reports demand solutions to the obsolescence and aging process suffered by the existing buildings, due to the growth and expansion of cities that took place in the second half of the 20th century [...]

It is estimated that at least one quarter of the world’s population will be affected by water shortages in the coming years and by 2030 there will be a global water deficit of 40% if urgent action is not taken. Currently, the main consumer of water globally is agriculture. In addition, it has been estimated that to meet the demand for food by 2050, the water available for agricultural irrigation would have to increase by 70%. In this context, wastewater could become a relevant water resource to meet this growing demand. This article aims to show the state of the global research on sustainable use of wastewater in agriculture. To this end, a systematic qualitative analysis and a quantitative bibliometric analysis were conducted. The search was carried out for the period 2000–2019, and the analyzed sample comprised 1986 articles. The results show that this line of research is one of the most outstanding within agriculture and has gained special relevance during the last five years. Research has improved significantly at a technical level, but problems such as energy consumption, and the elimination of heavy metals and elements of chemical and pharmacological products, still need to be refined. There is a particular lack of contributions covering social aspects. This article can serve as a reference for both researchers and stakeholders interested in this topic.

Solar photovoltaic (PV) energy systems are one of the most widely deployed renewable technologies in the world. The efficiency of solar panels has been studied during the last few decades, and, to date, it has not been possible to displace the production of energy using crystalline silicon wafer-based technology whose efficiency has reached values around 26.1%. Moreover, using solar tracking PV systems has become a feasible alternative to increase the electric output of PV silicon technologies instead of using the conventional fixed PV installation on a flat or sloping surface. The following study has compared fixed and dual-axis sun-tracking PV panels in order to quantify the enhancement associated with the amount of energy harvested when using dual-axis tracking PV systems in the city of Manta, located in a coastal region of Ecuador. In order to carry out this study, an IoT monitoring system based on Raspberry Pi3 and Arduino platforms was used. Measurements of solar radiation (W/m2), light intensity (Lux), temperature (°C), short-circuit current (A), and open-circuit voltage (V) were taken every minute for both systems. The results prove that the dual-axis tracking PV system produces, on average, 19.62% more energy than the static PV system. These results present an 8.62% energy increase with respect to a previous study carried out in an equatorial region with similar characteristics to those of the city of Manta, where a one-axis tracking PV system was used.

Higher Education Institutions are facing a challenging situation: how to introduce concepts such as Sustainability or the Circular Economy into their curricula. This study presents how to organize a Computer Reuse Program, an educational proposal for the Reuse, Repair, Refurbishment, Remanufacture and Recycling of computers into a Curriculum and a case study. The proposal is based in the Service-Learning methodology, by which students develop technical and professional skills while undertaking a project that has a direct and real impact on society. Students work on old or broken computers provided by donors, thereby acquiring technical skills. These now flawlessly functioning computers are donated to NGOs and other non-profit organizations, thus endowing the equipment with a much longer life as well as reducing e-waste, one of the fastest-growing waste streams in the world. As a case study, this paper presents the UPC Computer Reuse Program, carried out at Universitat Politècnica de Catalunya UPC-BarcelonaTech. Since the program started in 2004, some 2500 computers have been donated to 359 different organizations in 29 countries, and more than 5200 students have participated. The paper analyzes the impact of the program on society, on the reduction of e-waste, on the environment and on student awareness regarding social justice and sustainability.

(1) The amount of plastic discharges in the environment has drastically increased in the last decades negatively affecting aquatic ecosystems, societies, and the world economy. The policies initiated to deal with this problem are insufficient and there is an urgency to initiate local actions based on a deep understanding of the factors involved. (2) This paper investigates the potential of massive open online courses (MOOCs) to spread environmental education. Therefore, the conclusions drawn from the implementation of a MOOC to combat the problem of marine litter in the world are presented. (3) This work describes the activity of 3632 participants from 64 countries taking an active role presenting useful tools, connecting them with the main world associations, and defining applied action plans in their local area. Pre- and post-questionnaires explore behavioral changes regarding the actions of participants to combat marine litter. The role of MOOCs is contrasted with social media, formal education, and informal education. (4) Findings suggest that MOOCs are useful instruments to promote environmental activism, and to develop local solutions to global problems, for example, clean beaches, supplanting plastic bottles, educational initiatives, and prohibition of single-use plastic.