[en] Sustainable Development is one the most frequently addressed issues nowadays and the search for its comprehension is a major challenge for researchers. Nevertheless, to reach its understanding and the relations comprised (economic, social, environmental and institutional dimensions) is not the only challenge. To measure the route for a society development is an equally important matter, mainly due to intrinsic relations among environment, society and economy. This work presents a new approach in the construction of a synthetic index for sustainable development, under the point of view of energy sustainability. This methodology was based on mathematical archetypes structured in Fuzzy Logics, thus allowing the incorporation of new knowledge bases, even with vague definitions. The final result is the creation of an Energy Sustainability Index that may be accompanied along the time, allowing comparisons among countries, since it uses a database from the 'Guia de Indicadores Energeticos de Desenvolvimento Sustentavel' (Guide of Energy Indicators for Sustainable Development) from the IAEA. This guide presents an energy indicator methodology worldwide accepted and it was conceived to be similar to other indicators, such as the 'Indice de Desenvolvimento Humano (IDH)' (Human Development Index), developed by The United Nations Organization and which is of easy comprehension, since it is represented by a number between zero and one. (author)