The adequate assessment of the thermal performance of a building requires the knowledge of its characteristics within its inserted context, making it possible to verify the actual and future performance of the building. Therefore, this study aims to analyse the energy efficiency of a public university building located in southern Brazil. The assessment was carried out according to the Brazilian Technical Regulation for Energy Efficiency Labelling of Commercial, Services and Public Buildings (RTQ-C). In this study, the building envelopment was evaluated under the actual condition and in the reference condition, using the simplified method. The constructive parameters of the building were obtained from the architectural project and technical standards, although the assigned climatic group of the building was defined based on the Brazilian bioclimatic zones. In the end, it was possible to identify the energetic efficiency level of the envelopment through the total annual thermal load of the building in its actual condition. Considering the urban and climatic context, as well as constructive characteristics of the building, strategies were proposed that can be adopted even in the project planning stage, aiming to improve the classification of the envelopment and to meet the energy efficiency policies of the country.