The main objective of this paper is to present the advantages of using Cost-Benefit analysis in energy efficiency projects implemented in public buildings, and to prove the hypothesis that Cost-Benefit analysis boosts the effectiveness and efficiency of the said type of projects. The paper offers theoretical and practical explanation of the implementation of Cost-Benefit analysis in the relevant area. Since energy efficiency projects in public buildings usually represent a part of a broader portfolio of similar projects and their implementation demands allocation of substantial financial resources, communities are often be interested in achieving maximal economic and non-economic benefits. This paper aims to demonstrate that Cost-Benefit analysis can represent an excellent contribution when attempting to select the projects for implementation within a broader portfolio of energy efficiency projects in public buildings. This hypothesis was demonstrated by putting a greater emphasis on non-economic benefits and the costs arising from implementation of the aforementioned types of projects. In addition, a practical test of this hypothesis was performed through the implementation of an energy efficiency portfolio in public buildings, worth several tens of millions of dollars - the Serbian Energy Efficiency Project. The paper concludes that the use of Cost-Benefit analysis can help us to effectively evaluate and manage projects of this type aimed at achieving maximum benefits for the community in question