The unfortunate economic situation involving Spain and the European Union is, among other factors, the result of intensive construction activity over recent years. The excessive consumption of natural resources, together with the impact caused by the uncontrolled dumping of untreated C&D waste in illegal landfills have caused environmental pollution and a deterioration of the landscape. The objective of this research was to generate a selective classification and quantification model of C&D waste based on the material resources consumed in the construction of residential buildings, either new or renovated, namely the Conventional Constructive Model (CCM). A practical example carried out on ten residential buildings in Seville, Spain, enabled the identification and quantification of the C&D waste generated in their construction and the origin of the waste, in terms of the building material from which it originated and its impact for every m(2) constructed. This model enables other researchers to establish comparisons between the various improvements proposed for the minimization of the environmental impact produced by building a CCM, new corrective measures to be proposed in future policies that regulate the production and management of C&D waste generated in construction from the design stage to the completion of the construction process, and the establishment of sustainable management for C&D waste and for the selection of materials for the construction on projected or renovated buildings.

In recent years, the building sector has been turning towards intervening in the existing city building stock. In fact, it is generally accepted that the refurbishment of buildings and the urban regeneration based on sustainability must form the axis of reformulation of the building sector. Nowadays, achieving sustainable urban development inevitably involves improving existing buildings, thereby preventing the need for city growth, and for the emptying of established neighbourhoods. Furthermore, considering the whole life cycle, it is well known the great amount of greenhouse emissions derived from the construction sector, so in order to reach a decarbonized society it is important to provide eco-efficient construction materials and solutions, adding the principles of circular economy and resource efficiency. The articles of this special issue show different aspects to be considered in order to reach a decarbonized and circular building stock.

Highlights System for diagnosing the built environment from the perspective of the elderly. Assessment procedure based on 35 variables organised in 7 key dimensions is defined. Operation and replicability of the system are tested in international case studies. Key outcomes are discussed regarding ideal weighted values for ageing in place. Implications for deciding age-friendly measures with social acceptance are provided.

Performance-driven optimization has shown its potential to integrate design and energy performance, since building shape and envelope are determinant to the energy demand. Even though new buildings should be nearly zero energy buildings by 2020, according to European Directive 2010/31 recast, they only represent a minority of the building stock. Building retrofit has demonstrated a great potential to reduce energy consumption, and at the same time, CO 2 emissions. The scope of this work is to present and test a design methodology to enable architects and decision makers to couple building shape and envelope with energy and financial performance in a multi-objective optimization method. Our multi-objective optimization model is adaptable for both conceptual design and building retrofit, and presents effective application to assist design decisions in a seamless workflow. In this case study, we have applied the model to a housing block retrofit in Seville. We have designed indexes to optimise building envelope, considering mild climates issues. Then, we have simulated heating and cooling demand of the optimal solutions and calculated Net Present Value (NPV) to obtain their financial feasibility. The results have shown the robustness and validity of the framework.

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Is it possible to carry out eco-sustainable rehabilitations on specially protected buildings? This is the main question and starting point for this research. We will use the tower of the Church of “Santiago Apóstol” in Montilla as a case study; with its most remote antecedents in the 15th century, it is an emblematic building of one of the most important cities in the Cordovan countryside and is listed as an Asset of Cultural Interest (Bien de Interés Cultural or BIC) as of 2001. The application of eco-efficiency criteria in the rehabilitation of this type of building might stimulate the reactivation of the construction sector in the rural area, positively impacting the promotion of a circular economy. To this end, a general methodology has been established for carrying out eco-sustainable renovations on this type of building, which defines indicators for evaluating the eco-sustainability of such interventions. This methodology is applied to the case study of this important building in Montilla to ensure that a feasible intervention has been proposed, aligned with three basic pillars of sustainability that considers its environmental, economic, and social impact.

Currently, one in eight people live in neighborhoods with social inequality and around one billion people live in precarious conditions. The significance of where and how to live and in what physical, spatial, social, and urban conditions has become very important for millions of families around the world because of mandatory confinement due to the COVID-19 pandemic. Today, many homes in poor condition do not meet the basic requirements for residential environments in the current framework. Theoretical models for the urban evaluation of this phenomenon are a necessary starting point for urban renewal and sustainability. This study aims to generate a model for evaluating homes in a situation of social inequality (hereinafter Vrs) with indicators on physical, spatial, environmental, and social aspects. The methodology used in this study evaluates housing, taking into consideration habitability factors (physical, spatial, and constructive characteristics), as well as the qualitative characteristics assessing the satisfaction of users with the adaptation and transformation of the housing and its surroundings. The application of 51 indicators distributed in four previous parameters was established for this study. This quantification identifies the deficiencies of the dwellings and sets the guidelines for the establishment of future rehabilitation policies for adapting the dwellings to current and emergency scenarios. The innovation of this study is the construction of a tool for social research surveys designed to include individual indicators from the dwellings’ users, to provide a more dependable representation of the problems found in Vrs. The results of this research identified the deficiencies of precarious housing and could be used for applying effective proposals for improvement of habitability and their surroundings in the future. Furthermore, the results showed that when all the indicators were considered, the level of lag reached would be similar to that of a real housing situation, further confirming the suitability of the methodology applied in this investigation.

Building Information Modeling (BIM) constituye una herramienta versátil para analizar el ciclo de vida de los edificios y el uso eficiente de los recursos, reducción, reuso y reciclado de residuos de construcción y demolición hacia un parque edilicio sin carbono para 2020 en Europa. Este trabajo propone una nueva metodología para incorporar indicadores: energía incorporada, emisiones de CO2, residuos de construcción y demolición además de sólidos urbanos, en modelos BIM que evalúan el impacto ambiental siguiendo la estructura de la Base de Costes de la Construcción de Andalucía (BCCA). Se eligió un bloque de vivienda social en Sevilla, como caso de estudio, para focalizarse en el análisis de su estructura de hormigón armado debido a su alto impacto.Los resultados agrupados por tarea e indicador muestran el rol preponderante del hormigón. Por el contrario, el acero demuestra ser menos energo-consumidor, generando menos emisiones y permitiendo reducir los residuos mediante reciclaje. Según la discriminación por tareas, se destaca el bajo impacto de las fundaciones frente a la superestructura resistente. Asimismo, cada metro cuadrado de construcción típica genera 76.11 de residuo de construcción y demolición, siendo 76,11 kg mixto proveniente del hormigón y 0,34 kg, del acero. Palabras clave Energía incorporada, emisiones de CO2, residuos de demolición y construcción, diseño por ordenador ABSTRACT Building Information Modeling (BIM) has become a versatile tool to analyze the building life cycle and to achieve the efficient use of natural resources and the reduction, reuse and recycling of construction and demolition waste towards the goal of a decarbonized building stock for 2020 in Europe. This research proposes a new methodology to introduce embodied energy (EE), carbon emissions (CE), construction and demolition waste (CDW), and urban solid waste (USW) indicators into BIM models that assess environmental impact following the structure of the Andalusian Construction Cost Database (ACCD). A block of social housing was chosen as a case study in order to focus on the analysis of its reinforced concrete structure due to its high impact. The results, grouped by task and indicator, show the dominant role that concrete plays in environmental impact. In contrast, steel proved to consume less energy and generate fewer CE as well. Moreover, steel may be recycled, while reducing the quantity of waste. When analyzed by task, the foundations cause much less impact than the tough superstructure. Likewise, each square meter of the typical housing block generates 76.11kg of CDW, with 76.77 kg of mixed concrete waste and 0.34 kg of steel waste.