In contemporary European urban landscapes, the presence of 19th and 20th-century modern period architecture stands as a defining characteristic, contributing significantly to EU Built Heritage. These structures serve as substantial reflections of local and national identity. However, despite their historical significance, many of these buildings present considerable challenges in terms of energy efficiency, particularly in heating and cooling systems. Addressing this issue is crucial for preserving their cultural value while aligning with contemporary sustainability goals. The SINCERE project endeavors to explore the intrinsic worth of Built Heritage while offering practical solutions to improve energy performance and reduce the carbon footprint of historic buildings. Through the integration of innovative restoration materials, energy-efficient technologies, ICT tools, and socially innovative approaches, SINCERE aims to facilitate the transition of these structures towards net-zero carbon emissions. Adopting a holistic approach, the project encompasses various scales, from individual building components to entire cityscapes, considering factors such as structural integrity, architectural uniqueness, and local environmental conditions. Additionally, SINCERE aims to empower stakeholders with innovative solutions covering the entire lifecycle of buildings, from restoration to maintenance. By providing sustainable restoration options and raising awareness through outreach, the project fosters a culture of preservation within European communities, securing the legacy of Cultural Heritage for future generations.