Knowledge of buildings′ energy efficiency has advanced thanks to research carried out in recent years. Many of the discoveries in this field have recently been incorporated into mandatory construction regulations for each country. However, not many of the architects and engineers involved in the construction industry clearly know how to achieve those goals in their designs. This document is based on the extensive experience in architectural design, the integration of renewable energies, the energy simulation of buildings and data acquisition, and analysis of the research team involved. It is presented in a practical and holistic approach and focused in subtropical climates. A structured methodology for the proper decision-making process during all the different stages of a minimum energy building (MEB) is likewise presented. The proposed methodology depicted aims at providing architects and engineers with a systematic and orderly step-by-step procedure and incorporates the instrumentation/control and data analysis as essential elements that support the validation of the expected results from the design, the construction, and the operation phase of the building. The paper develops a case study that illustrates the proposed methodology. This new methodology for MEB in subtropical climates constitutes an innovation in this field.