Big amount of data produced, exchanged and stored during a building’s lifetime, along with the increasing adoption of IoT technologies, provide a huge potential for the development of data-driven services that can facilitate processes such as predictive maintenance or monitoring of KPIs that are required for demonstrating climate policy compliance. On the other hand, storing and sharing information among interested stakeholders, can generate critical privacy and trust issues. In this paper, we present a blueprint architecture based on a combination of state-of-the-art and disruptive technologies, introducing the concept of a modular Trusted Digital Building Logbook (DBL) that will act as a dynamic record at facility level and will segregate monitored data and other building related information, in a way that guarantees both the privacy of confidential data and the transparency to authorities and city stakeholders that wish to have a real-time overview of buildings’ performance at a local or regional level. The Trusted DBL is based on Blockchain and Digital Twin (DT) technologies and can be used to report progress on emission reductions, the impact of a given energy efficiency measure or to recommend precautionary measures ahead of critical events such as heatwaves. Designed to be interoperable, the Trusted DBLs of different buildings clusters are linked together to capture critical information at national, organizational and/or facility level, help understand a region’s emissions profile and report it in the form of an emissions inventory.