This chapter provides an overview of common economic analysis methods that can be utilized to determine the cost-effectiveness of a wide range of energy efficiency measures and distributed generation technologies suitable for buildings. The purpose of this chapter is to describe simple yet rigorous evaluation methods, including life cycle cost (LCC), analysis technique, and levelized cost of energy (LCOE) analysis approach, used to make decisions about designing and retrofitting building energy systems. The simple payback period method is also presented since it remains widely used in the preliminary design or retrofitting stages of energy-efficient buildings and distributed power generation systems.