Buildings are one of the largest contributors of greenhouse gas emissions and, in the United States, they are the largest energy users. To combat these emissions, policy makers suggest retrofitting older buildings to achieve better energy performance. (The authors define retrofit as any changes to an existing building that improve the building's ability to perform or extend the building's life.) Despite consensus that buildings should be retrofit, building owners may struggle to identify how to retrofit their building. This paper addresses this gap by providing a proposed lean process, rooted in Choosing by Advantages (CBA), for selecting among potential energy retrofit options.In this paper, the authors present the energy retrofit decision-making process recommended by the U.S. Department of Energy and compare it to those used in practice on case studies completed in the last five years. The authors identified two shortcomings in the implemented processes: first, the decision-making processes only consider the designers' perspective on energy and cost savings with little involvement from other stakeholders, and thus, they may ignore the needs, desires, and opinions of others with non-design backgrounds; second, these processes consider more design alternatives than may be realistic for a building owner given budget and schedule constraints.To make the process leaner, the authors propose a new energy retrofit decisionmaking process, rooted in CBA, that addresses the previously-identified shortcomings. This process involves more stakeholders in the decision-making process. Moreover, this process helps decision-makers focus on the most promising design alternatives, thereby supporting better use of time and increased likelihood of a successful retrofit.