The objective of this study is to evaluate the annual hygrothermal and energy behavior of a school building belonging to the "700 Schools" National Program in the Metropolitan Area of San Juan, Argentina. To this end, stationary state calculations were made using IRAM standards. Monitoring was performed at three key times during the years 2013 and 2014 with the building under real occupation conditions. This data was processed and related to daily energy consumption readings. Additionally, comfort levels in three classrooms were studied using the Fanger method, and PMV and PPD indices were determined with a specific software. Finally, historical electricity and gas consumption were computed, and values per unit area were calculated, which were compared with national data and international standards. The analysis carried out, based on theoretical and empirical data, supports the conclusion that with an average annual consumption of 88 kWh/m2 the building meets international standards of school energy efficiency. However, its thermal performance is deficient in cold and warm seasons, as evidenced by rooms that are outside the comfort zone most of the time.