Some public buildings, which date back to the 1980-1990s, often miss to comply with comfort basic requirements. Also, their energy consumption is often above thresholds posed by regulations presently in force. Hence, low-cost technology improvements for renovation with high return on investment is a good opportunity in order to limit the required budget. To this purpose, the integration of advanced control policies may optimize energy use of buildings with minimum hardware enhancement. In this paper, we evaluated the performances of an existing building that belongs to the campus of the Università Politecnica delle Marche (Ancona, Italy), and that is made of offices, teaching rooms, laboratories, library and other public spaces. Thanks to an extensive monitoring of indoor comfort conditions, the main inefficiencies in terms of comfort were analyzed and a Dymola model of the actual building was worked out. Then, some energy improvement actions were assumed and tested by means of numerical simulation in the Dymola environment, and the benefits in terms of comfort and energy saving were estimated. Meanwhile, a BIM model of the building was built, regarding both the present status and each improved scenario, that allowed to perform a detailed cost estimation of each scenario. As a result, a cost-benefit analyses of each renovation scenario was performed and all the options were compared. The analyses showed that some renovation actions could be supported by energy savings with reasonable return on investment.