On sustainability aspects through the prism of stone as a material for construction

Sustainability as a concept was developed in the last thirty years, as a reaction to the overexploitation of natural resources, the increase of greenhouse gas emissions and the degradation of the environment due to anthropogenic activities. Its essence lies in the preservation of the ecosystem and resources in order not to endanger the well-being of future generations. The present dissertation attempts to further examine the concept of sustainability through the prism of stone and stone buildings, by treating all three dimensions: environment, society and economy. The ultimate goal is to better understand the meaning of this concept and to provide tools and methodologies that will facilitate policy-makers and construction industry stakeholders define strategies and take decisions that will be in alignment with sustainable development. The choice of stone is related to the various sustainability features of the material, its longevity when used in construction and the values that it integrates. The study of stone at different levels (the level of the material, the wall and the building) which is followed in the present dissertation allows to examine multiple issues related to the construction sector. At the material level, the environmental impact of the extraction of stone is studied based on site visits of quarries in Switzerland. Extensive use of aggregates in some countries has led to overexploitation of the local resources and the risk of resource depletion is imminent. For this reason, it is important to focus on the local availability of construction resources. This thesis introduces a new indicator for evaluating the regional accessibility of stone intended for construction aggregates. The indicator reflects the impact of social factors on resource exploitation and expresses the space competition between built area and quarry based on land cover data. The indicator is validated for the cases of France and Switzerland, at a regional and national level. In addition, in order to calculate the criticality of stone in a region, the metal criticality methodology developed at Yale University is adapted to the case of natural aggregates. The adapted methodology is tested for the different cantons of Switzerland and the results are compared to the criticality of steel in the country. At the wall level, the life cycle assessment of various wall systems with stone (either massive stone or cladding) shows that the use of a thin cladding in the façade is not necessarily the most ecological solution and that the type of stone product to be used in a structure largely depends on the local availability of the material. At the building level, one of the buildings of the 60-year-old residential stone complex Résidence-le-Parc, in Paris, is used as a testbed to examine the concept of sustainability. A Life Cycle Assessment of the building is performed based on historic data from its life cycle, both its construction and maintenance. Different what-if scenarios for the refurbishment serve to examine what impact various interventions in the cell of the building can have on the embodied energy and the energy consumption. It is observed that although the building is a massive stone structure, the contribution of stone to the life cycle assessment and the thermal performance is minimal. Furthermore, the study shows that apart from the environmental and economic aspect, there is some hidden value in the use of stone in multi-ownership residential buildings, related to the social dimension. Moreover, the economic aspects of the construction of a project are examined through a new methodology introduced in this dissertation. This new methodology traces the economic flows in construction projects till the final recipient and the regional level that benefits from these flows. The goal is to facilitate economic decision making by evaluating the economic transformation of the society as a result of the specific project. The methodology categorizes costs into labor, materials, energy, infrastructure, taxes and overhead and into local and national. Three case studies of structures made out of stone and reinforced concrete are selected and analyzed to test the application of this method. The case studies show that the methodology developed and the representation by a Sankey diagram can provide useful insights both regarding the spatialized distribution of the cost of a project and the economic flows going to direct labor vs overhead and taxes. In conclusion, the examination of the multiple facets of sustainability pertaining to the construction industry, which was performed during this research, showed that a construction project has to take into account the interests of the different stakeholders and provide a reply to the questions where, how, with whom. Optimal results are reaped when these aspects are considered upfront in a project, in the design phase. Future work to complement the present dissertation could be directed toward the integration of the three dimensions of sustainability.