Development and Application of a Methodological Framework to support Sustainability Assessment in the Building sector – The Circular Building Passport

The building and construction sector is one of the most resource and carbon-intensive industries, with major implications for sustainability. Although recycling practices are expanding, most recovered materials are downcycled, stressing the urgency of shifting from a linear to a circular model. In this context, digitalisation and integration of sustainability data emerge as strategic enablers to enhance transparency and informed decisionmaking across the building lifecycle. This thesis develops and applies a methodological framework to support the implementation of a Circular Building Passport (CBP), in line with the European LEGOFIT project. The framework integrates four dimensions: environmental, circular, social, and economic, providing a holistic and operational tool for sustainability assessment. Environmental impacts are assessed through Life Cycle Assessment, circularity through the Material Circularity Indicator, the social dimension via comfort and post-occupancy indicators, and the economic one through Life Cycle Costing. The methodology was tested in the Luxembourg pilot case study. Data collection involved 28 products, of which only 19 had valid EPDs, revealing critical issues such as uneven data coverage and information gaps. The results confirmed the feasibility of the framework but also highlighted challenges, including the lack of operational data at design stage and the time-consuming nature of data processing. Despite these limitations, the environmental and circularity outcomes offered a robust picture of the pilot’s sustainability performance. The strength of the methodology lies in its modularity, scientific robustness, and adaptability. Future developments should focus on automating data collection and ensuring interoperability with BIM platforms. The CBP developed represents a replicable tool to assess sustainability performance, supporting both policymakers and practitioners in driving the transition towards a circular and low-carbon built environment.