The construction sector is very energy- and carbon-intensive. Evaluating environmental impacts is relatively complex, but the consideration of these factors is crucial for a key mitigation strategy. The main purpose of this study was to analyze the impact of a single-family house under different geographical situations. To do so, a comparative study is proposed between France (continental location) and Reunion (insular context). An Life Cycle Assessment approach has been used to define the impact at different steps of house construction. The specific emission was defined to take into account the mix of electricity generation, the import of materials, and the local manufacturing process. A comparative study was conducted between the French environmental Database INIES and factors created under GEMIS. This comparison provided some elements of validation of the defined processes for France. Thus, the adaptation of specific emission factors was possible for the Reunion case based on the same processes. Among the first results obtained (civil works), an overview of the Global Warming Potential (GWP), which is defined per m2 of residential house, was determined. The results for France and Reunion were 192.35 and 228.65 kg CO2 eq/m2, respectively. The difference of 18.87% highlights the effect of insularity due to the impact of building material import and mix of electricity. Thus, the greater impact of the construction sector in an island environment than in a continental environment is understandable because of products manufactured locally using a local mix of electricity. The energy vulnerability of an island area can have indirect consequences on the environmental quality of the territory. This case study can be considered useful when defining a sustainable planning strategy that aims to reduce environmental effects. Finally, this article aspires to fill the gap in the field of LCA for the building sector in a subtropical climate.