A circular economy is a current tenet that must be implemented in the field of construction. That would imply the study of the possibilities of the use of waste generated, for obtaining materials the used in construction as replacements for the raw material used. One of these possibilities is the substitution of the cement by slag, which contributes to the reduction of cement consumption, decreasing CO₂ emissions, while solving a waste management problem. In the present paper, different types of concrete made by cement substitution with different type of slags have been studied in order to evaluate the properties of these materials. Cement is replaced by slag from different steel mills, both blast furnace and ladle furnace slag. The percentages of slag substitution by cement are 30%, 40% and 50% by weight. Mechanical, physical and environmental properties have been evaluated. Compressive and flexural strength have been analysed as the main mechanical properties. As far as physical properties go, density and porosity tests were be reported and analysed, and from an environmental point of view, a leachate study was performed. It has been found that some kinds of slag (blast furnace slag) are very suitable as substitutes for cement, providing properties above those of the reference concrete, while other types (ladle furnace slag) could be valid for non-structural applications, contributing in both cases to a circular economy.

To achieve the goals of reducing building energy consumption, regulations are being designed to guarantee the appropriate energy performance of buildings. Both European and South American countries establish requirements of thermal properties of building envelope according to the climate zone, thus implying notable differences in climate classifications and technical requirements. This research provides a general view of advantages and limitations between the different state regulations of three South American countries (Argentina, Brazil, and Chile) and three European countries (Spain, Portugal, and France). A total of 792 simulations were conducted with Energy Plus by considering 12 different dwelling typologies in 66 climate zones. Building envelopes were adapted to the regulations of the various countries. Results showed tendencies of performance clearly different between the South American and the European countries, with the latter being those with the lowest energy demands. The cluster analysis of distributions of energy demand revealed that buildings located in similar climates but in different countries present very different energy performances. This research opens up the discussion on the development of more demanding policies related to thermal properties of buildings. Also, the analysis at a continental scale could reduce the differences between countries and guarantee a more sustainable life for the building stock.

The selection of indicators for the Observatory of Sustainability of the Algarve Region for Tourism (OBSERVE), poses challenges, namely which indicators are relevant to stakeholders and how to assure that information is available. To support the selection of the environmental, sociocultural, economic and institutional indicators, an engagement process was designed and applied, which included meetings with stakeholders, a workshop and an online survey. The results showed that both workshop and online surveys reflected, in general, similar opinions, thus allowing the selecting of the sustainable development indicators for the Algarve region. Additionally, the results showed that nearly 75% of the indicators can be obtained from national statistics and, therefore, can be used on the OBSERVE project, assuring a quick flow of information. As limitations, it is important to mention that the other 25% will need further development, in order to provide data for indicators, like carbon management and client satisfaction. With this approach, the observatory will survey and evaluate the sustainable development of the region (status and trends), based on indicators that answer to the strategic needs of system’s main users, with social and economic implications, i.e., public institutions, economic agents, tourists, local communities and residents.