The application of energy-efficiency strategies in buildings is a hot topic around the world; in some countries, there are regulations with more or less degree of compliance, but in most countries located in the tropical zone, there are no regulations, and it is not easy to transfer regulations of countries outside of tropical zone. For countries located in tropical zones, the implementation of strategies to reduce the heat flow from outside to inside buildings is a key point. As a case study, the Dominican Republic (DR) was chosen, and during 2020, an analysis focusing on buildings of the tertiary level was carried out with the goal of using scientific methodology focused on tropical climates that allows for a significant reduction in energy consumption by implementing Energy Efficiency Strategies (EESs) that are available, with minimal intrusion into the building and low cost. The study includes, as parts of the proposed methodology, the characterization of building parks, including the climatic zonification of the country, an in-depth study of the building typologies in DR, and a massive survey around the country about the technical characteristics of air conditioning units and their usage; the election and characterization of buildings, including simulation and validation throughout the monitoring of eight different buildings; ananalysis of the measures of energy efficiency and implementation in the models, including the election of a demonstrative building, the election of the most convenient EESs, modeling of EESs, implementing EESs in the building, monitoring, and validation; and ananalysis of the impact of the measures at the region or country level, throughout which important conclusions can be obtained in order to reduce energy consumption in the country. The results show that this methodology is a valid tool for countries situated in tropical areas in order to reduce the energy consumption associated with air conditioning units with low cost, availability, and no intrusive EESs.