Improving the energy efficiency of existing buildings in favor of reducing consumer demand and associated emissions is one of the central strategies for achieving global GHG (greenhouse gas) emissions reduction targets. Contemplating this activity within the paradigm of long-term sustainability implies, on one hand, that project intervention strategies must be assisted by tools that integrate social, environmental, and economic indicators that must be evaluated from an LCA (life cycle assessment) perspective and, on the other hand, deviations must be considerate of the energy-saving projections that are sought to be achieved through the potential strategies to be implemented. This article develops an LCA methodology whose objective is to evaluate the comprehensive sustainability of existing passive strategies in the local industry through the quantification of environmental and economic indicators throughout different climatic scenarios, which are socially contextualized for a building existing in a Mediterranean region. Part of the results obtained showed a loss of the effectiveness of measurements with an adequate response to the current climatological reality.