The process by which a building owner evaluates and decides upon energy conservation measures (ECMs) for a building retrofit is key towards achieving efficient results. However, many owners rely on unsophisticated evaluation methods, which potentially limits the amount of energy reduced in the commercial building. Reducing energy in the nearly 4.9 million commercial buildings is critical because they account for approximately one fifth of the total energy consumption in the United States. Reducing their energy consumption levels will have significant impacts on energy dependency, Greenhouse Gas emissions (GHG), and operations costs. The decision processes of twelve private and public organizations in New Mexico were evaluated through collective case study research. The processes of each organization were compared and key steps were identified. Then the most used and critical steps were combined to create an integrated decision approach that optimizes cost savings and GHG emission reductions. This integrated decision process involves five main steps: (1) Building Energy Data; (2) Energy Identification and Analysis; (3) Assessment; (4) Design and Planning; and (5) Approval.