The digital transition and decarbonization are strategic European objectives, supported at different levels by the Green Deal, the Energy Performance Building Directive (EPBD), and policies and tools such as the Energy Performance Certificate (EPC) and the Smart Readiness Indicator (SRI). The SRI measures a building’s ability to use intelligent technologies to reduce its consumption and increase the energy awareness of occupants for energy efficiency. Furthermore, today, it has a limited impact on national regulations and public decision-making. Its application presents challenges including those related to heritage conservation. This paper contributes to the Italian SRI framework through an experimental application in the renovation of a historic building in the metropolitan city of Reggio Calabria (Italy). The analysis evaluates the SRI’s adaptability by comparing its pre-renovated state, current state, and pre-design plan. The SRI calculation integrates assessment tools with BIM models for a potential future digital twin approach. The study, part of a funded national research project, aims to enhance policies for digitalization in the green transition. The paper is organized into the Introduction; Materials and Methods, which contains the methodological approach; Results; and Discussion and Conclusions. Following the experimental application, the results show that standardizing the SRI approach could enhance energy efficiency and digitalization in buildings.