This research paper aims to contribute to the improvement of sustainable management of Peruvian buildings throughout the project lifecycle by integrating the Lean Construction philosophy and sustainability concepts through the Delphi method. First, the literature is reviewed and the existing information on compatibility or synergy between Lean Construction and sustainability management systems is analyzed. After that, with the support of a collaborating company, a methodology for evaluating sustainability performance in projects is developed, which integrates the Last Planner® System and sustainability management. The proposed tool is validated by the Delphi method, for which we solicited expert opinions on the study topics. Next, the proposed methodology protocols corresponding to the evaluation of the design, construction, and use phases of the buildings are developed. Finally, the methodology is applied to five case studies, the results are analyzed, and the methodology is validated. Throughout the research, the principles, tools, techniques, and practices of the Lean philosophy are analyzed, which synergize with the methodologies, standards, and tools of sustainability management.