Using sensible heat storage (SHS) in buildings with high thermal mass can support energy efficiency; in retrofits, as well as in buildings with lower thermal mass, using SHS might not be feasible due to the lack of thermal mass required to maintain comfort in a volume of air (i.e., in a room within a building). Therefore, applying Latent Heat Thermal Storage (LHTS), such as Phase Change Materials (PCM), can be more effective to enhance these buildings’ thermal behavior. PCMs have a high heat of fusion; during the phase change between solid and liquid, a large amount of thermal energy can be stored and released in these materials. This paper presents a detailed analysis of PCM behavior seen in sample retail buildings located in Arizona, a hot- dry climate. This paper presents the impact of air circulation in the plenum space, on PCM efficacy and energy performance. This paper comprises experimental work as well as EnergyPlus model results to determine the factors that can increase the efficacy of PCM integration. In particular, results indicate that air circulation in the plenum promotes convection heat transfer between the air and the PCM sheets, resulting in reduced energy consumption. Finally, the paper evaluates cost saving potential for consumers, as well as the potential for peak load reduction for utility providers.