The research presented in this paper has two main objectives. First, it aims to generate an assessment tool for ranking and selecting the most sustainable domestic waterheating system (WHS) (with the lowest economic, environmental and social impact) that could be applied in any location and with any demand. Second, it aims to ascertain which WHS is the most sustainable in places with a climate and solar radiation like that of Barcelona, Spain, where a minimum solar contribution to domestic water heating is compulsory for new buildings and significant renovations. Multi-criteria decision analysis was employed to create the optimised flexible assessment tool. The Delphi method was followed to perform the surveys, and to provide the objectivity required in the identification of impacts, the definition of indicators and the assignment of weights. The most relevant criteria were determined: annual cost, material consumption, energy consumption, GHG emissions, space requirement, visual impact and occupational risks.The resulting tool was tested by analysing twelve domestic WHS, including two conventional systems, and ten combinations of five solar thermal technologies with two conventional systems as backup for a changing room in a sport centre located in Barcelona. The two conventional WHS studied were a natural gas-fired condensing boiler and an electric water heater. The five solar thermal technologies were: a flat plate with a harp design, a flat plate with a serpentine design, a heat-pipe evacuated tube, a direct-flow evacuated tube, and a direct-flow evacuated tube with CPC. The dynamic thermal simulation programme T*SOL was used to dimension the solar thermal systems. Two sensitivity analyses were carried out: one on weights and one on references. The tool proved very useful in the assessment of these systems, and could also help in decision-making processes to select the most sustainable WHS for other locations and domestic hot water demands.

Fibre-reinforced concrete has been used in structures without any additional reinforcement when the design is determined by transient load stages (precast segments for tunnels), in elements with favourable boundary conditions, and in structures subjected to low load levels (pavements or pipes). Recently, the material has been used as the primary reinforcement in elements with greater structural responsibility, such as building column-supported slabs. Several dozen buildings have incorporated this new technology, and research is being conducted on how to optimise the design whilst guaranteeing the required reliability levels. However, in some cases, fibres have not been used as the primary reinforcement in concrete slabs for economic reasons. In most cases, the solution is compared with existing alternatives (traditionally reinforced concrete) considering only the direct material costs and disregarding indirect costs, social aspects and environmental factors. The building construction sector lacks sustainability rating tools to assess structural components separately (e.g. columns, floors, panels, façades). This paper presents a new method that can be used to assess the sustainability of concrete slabs by means of a multi-criteria decision-making approach including fibre-reinforced concrete. To this end, it uses rigorous analyses of current concrete slab technologies and sustainability assessment tools. Criteria, indicators, weights and value functions have been specifically selected, defined and calibrated for this research.

Narrow trenches are a common technique for the installation of utility pipelines of small diameter. The excavated soil is not always appropriate as landfill and, in those cases, an appropriate soil from somewhere else (ex. a borrow pit or another construction site) should be used instead (classical solution, CS). Another common solution is to use a controlled low-strength (cementitious) material (CLSM) as backfill instead of compacted soil. However, both solutions lead to increased raw material consumption, waste generation, need for transportation, and CO2 emissions. In an attempt to address these issues, researchers developed an eco-trench (ECO) that reuses the excavated soil of narrow trenches to produce a controlled low-strength material to be used as landfill. Although technically viable, the sustainability of this solution versus the traditional solution has not been properly addressed. Hence, this paper aims to develop a method for the sustainability assessment of trenches. The Sustainability Index of Trenches (SIT), based on the MIVES decision-making method, enables the assessment and prioritisation of different types of trenches according to sustainability criteria. Criteria, indicators, weights and value functions were specifically defined based on seminars with experts in the field of utility services and construction. A case study was performed in which four types of trenches (CS, CS with recycling CS+R, CLSM and ECO) were assessed and prioritised according to SIT. ECO resulted in the most sustainable alternative with a SIT of 0.80 out of 1 followed by CS+R, CS and CLSM with SITs of 0.63, 0.40 and 0.38 respectively. The sensitivity analysis showed consistent results in different scenarios. These findings demonstrate the capability and reliability of SIT as a decision-making tool for the 2 evaluation of the sustainability of different construction processes for trenches and the prioritisation of the most suitable solution for different situations.

This paper presents a quantitative environmental impact assessment tool for the decision making of construction processes including structures, infrastructures and buildings by means of an Environmental Impact Index (EII) to be applied at design and/or construction stages. The research is based on multi-attribute utility theory, interviews with experts representatives of the different stakeholders in construction, and an analysis of fifty-nine European and Spanish environmental legislative acts. The resulting tool was applied to two construction alternatives for road drains (one precast and one cast-in-place). The findings show that the tool enables the prioritisation of construction processes and the selection of the best alternative in terms of environmental impact and that the results are stable to reasonable weight variations. The tool contributes to decision making in the context of project management in construction: it can help professionals in public administration, and design and construction companies. It helps to quantify the cradle-to-gate impact of construction work, which has usually been less studied than the operational impact in the life-cycle assessment of buildings. The tool is being piloted in construction projects of the Barcelona City Council.Peer ReviewedPostprint (author's final draft

The design of sustainable sewerage infrastructure is fundamental for achieving long-term sustainability goals. Piping systems are essential components in the water supply chain and in waste disposal systems worldwide. Among possible designs for concrete pipes, steel cages consisting of curved rebars have been predominantly used as reinforcement. However, structural fibres have emerged as an attractive technical and economical alternative for substituting steel cages. Due to increasing urbanisation, thousands of kilometres of pipes will be constructed in the near future. At present, decisions regarding reinforcement of concrete pipes are primarily cost-driven. To consider other aspects, it is fundamental to identify and quantify potential sustainability issues properly. Hence, this paper focuses on the sustainability analysis of reinforced concrete pipes using a multi-criteria decision-making method. A model based on criteria, indicators, weights and value functions is developed and calibrated by assessing various concrete reinforcement strategies (steel bars or steel/synthetic fibres). The main contributions of the article are the proposal and application of a model for the case of concrete pipes which can be adapted for other case studies; determining how different typologies of pipes contribute to the overall sustainability of infrastructure systems; and the use and application of a robust and interesting multi-criteria decision-making methodology. The results show that fibre reinforced concrete pipes are promising alternatives in social, economic and environmental terms. Both the model and results are expected to be useful to stakeholders in decision-making processes.

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Factors such as global urbanization, scarcity of land, and rising land prices will increase the need for high-rise buildings. Population growth has led to dense life in residential high-rise buildings (RHRB). On the one hand, RHRB have benefits such as the maximization of land use. On the other hand, disadvantages such as ignoring features of cultural context, difficulties in guaranteeing natural ventilation and the high maintenance expenses are considered as their weaknesses. According to previous studies, most current RHRB do not consider social cohesion and local identity. Studies have proven that dimensions of social sustainability have been scarcely considered. The main objective in sustainability assessment of RHRB consist in reducing the environmental impact and increasing the efficiency and residents’ satisfaction. Recent studies have considered modern methods for assessing the sustainability; in this regard, multi-criteria decision-making (MCDM) approaches are one of the most common alternatives to assess sustainability. The aim of this research is to develop a MCDM tool oriented to specifically assessing sustainability by using the Integrated Value Model for Sustainability Assessment (MIVES). The MIVES approach allows minimizing subjectivity in decision making while objectively integrating economic, environmental and social factors. In this paper, a new sustainability assessment model, which has been specifically configured to analyse social parameters for high-rise residential buildings, is presented. The findings show that most of the RHRB aspects positively affect the characteristics of the buildings and surroundings, while also affecting the psychological needs of humans.

In principle, the research-teaching nexus should be seen as a two-way link, showing not only ways in which research supports teaching but also ways in which teaching supports research. In reality, the discussion has been limited almost entirely to the first of these practices. This paper presents a case study in which some student fieldtrip construction projects, originally designed as a teaching tool, were also used to undertake environmental research. The research consisted of testing the implementation of a tool for assessing the environmental impact of construction sites. It was conducted at the Imperial College London Constructionarium Field Module 2012 at the National Construction College, in England. The findings highlighted the unexploited research potential of the Constructionarium teaching tool specifically and of field-trip teaching events generally. To a lesser extent, the students also learned about the research content and process. This experience could be extended to other field-trip teaching events.2