At present, energy represents a key element in the social and economic development of a territory. This is particularly true for fragile territories that are not interconnected, such as small island states. As is true for many of the Small Island Developing States (SIDS) worldwide, the energy situation of the Comoros is substantially based on fossil fuel imports. The socioeconomic development of this archipelago is overwhelmingly dependent on energy security from sustainability, availability and affordability perspectives. As a forward-looking response to energy vulnerability, the deployment of renewables to diversify the generation of electricity appears to be an essential prerequisite for guaranteeing a sustainable future. Nevertheless, despite a high potential for renewable energy, only 3.8% of the electricity supply in the Comoros is provided by hydropower. This paper provides a comprehensive overview of the energy situation throughout the Comoros and focuses on renewable energy opportunities to facilitate the supply of green power. This study ultimately shows that renewable energies are rarely exploited despite the powerful potential of different resources. Finally, this paper attempts to provide recommendations for the Comoros to pursue a more sustainable future.

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-CO2eq/m2 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.

A thorough understanding of the mechanisms influencing electricity use is imperative for the implementation of energy scenarios. This study first explores Madagascar's electricity consumption during the 1987-2015 period using a decomposition method. Next, a sensitivity analysis (SA) is conducted, which allows factors that have a significant influence on the different effects (activity, structure, and intensity) to be defined. Scenarios are then designed from regression models based on the SA. The main results revealed the following. (1) This study confirmed that the activity factor was the driving force of energy growth, accounting for more than 107.5% of the total electricity consumption. (2) The negative impacts of structural and intensity effects are particularly marked in periods of political disruption. (3) National energy policy (called "New Energy Policy" (NPE)) based scenario shows a significant electricity variation of 4084 GWh over the 2015-2030 period.. By minimizing the intensity effect change to 9.87% between 2015 and 2030, the NPE scenario's total consumption increase is limited to 4084 GWh. By contrast, this amount is 398 GWh for the BAU scenario with a 22% intensity effect. These developed scenarios seek to illuminate the tradeoffs entailed by the various development paths toward Madagascar's ambition to become an emerging country.

The building sector is responsible for 43% of France’s final energy consumption and is strongly associated with a high environmental impact due to its high consumption of energy and natural resources. These impacts are significant in isolated islands. Due to its geographical isolation and an area of 2512 km2, Reunion Island has a heavily carbon-based economy with a high import rate of raw materials for the building sector. This study aimed to investigate the effect of electricity mix decarbonization on residential house environmental impact. The methodology consists of three parts: (i) evaluating environmental impacts of Single-Family Houses (SFH) using life cyce assessment(LCA), (ii) defining SFH typologies using the K-means clustering algorithm, and (iii) implementing energy scenario in LCA of SFH to assess decarbonization effect. The environmental results were particularly sensitive in the operational phase, with a decrease of 83% between 2020 to 2040 of the global warming potential (GWP). The structural phase highlights the weight of imports in the building sector, as a decrease of only 1% is observed. This study clearly shows the necessary energy transition for Reunion Island. In the structural phase, the study recommends that stakeholders reduce imports and increase the share of recovered materials to achieve a substantial reduction in impacts.

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