Environmental Overcost of Single Family Houses in Insular Context: A Comparative LCA Study of Reunion Island and France

The building and public works sector is, in France as in Europe, a major consumer of raw materials for both the manufacture of products and the construction of buildings and structures. This sector has a direct impact on the natural and built environment. This effect is even more pronounced in the case of isolated territories, such as islands. The latter have their own constraints (geographical location, production of the local grid mix) and particularities: very small territory, massive importation of goods in all fields, such as food, automobile, building, and others). In this study, we focus on the building branch of the construction industry, which covers housing (single-family houses and apartment blocks). The study is based on the analysis of about twenty single-family houses built in metropolitan France and Reunion Island. The construction standards for these two regions comply with European standards (CE) and French regulations. However, in the case of Reunion Island, a tropical island, it applies in particular to the Thermal, Acoustic, and Ventilation Regulations for New Buildings in Overseas Departments and Regions (RTAA DROM). The approach that is used for the environmental assessment of single-family homes is the Life Cycle Assessment (LCA), from cradle to grave. The results initially showed that there is an additional environmental cost in the construction sector between France and Reunion Island. This is initially due to the choice of origin of materials and products, which can greatly contribute to the impacts of construction. Secondly, to the use of the countries’ electricity mix, which also contributes, in part, to the impact of the construction of these single-family homes during the assembly and transformation of the products. Finally, this additional cost also differs according to the transport used (sea, air, rail, road). For the Global Warming Potential (GWP) indicator, in our study we note that the additional environmental cost is 37% higher in Reunion Island. This figure explains the additional impact of the 218 kg-${\mathrm{CO}}_{2\mathrm{eq}}/{\mathrm{m}}^2$ of built-up area built for Reunion Island. This study is one of the first analyses demonstrating the additional environmental cost that exists between mainland France and overseas France. Thus, the results demonstrate the importance of creating a specialized and regionalized database for the case of remote islands. Thus, this database would allow for professionals to have a precise environmental assessment, not on a national but on a regional scale. This document also provides a framework and guideline for policy decision-making in the overseas islands.