Thermal energy storage (TES) plays an important role in enhancing energy efficiency and flexibility in building systems. This study develops a method for conducting life cycle assessment (LCA) studies for evaluating the environmental performance of TES in different configurations. A case study is carried out, comparing phase change material (PCM)-TES, water-TES, and borehole-TES. Cradle-to-grave life cycle inventory is analyzed over a 25-year lifetime, and ReCiPe 2016 midpoint (H) is used for midpoint impact categories quantification. Results show that TES integrations yield the lowest life cycle impact in global warming potential (GWP), surplus ore potential, marine eutrophication and water consumption among others against non-TES reference during operational phase. It is also shown that the predominant GWP impact of TES integration comes from production, installation, and end-of-life phases.