Compliance challenges in recycled material incorporation in buildings

Given the potential circularity of the construction sector, this study assesses the incorporation of recycled materials in building construction within the European Union. The Portuguese legal framework sets a unique target, requiring that at least 10% of the total materials used in public works consist of recycled materials or materials containing recycled content. This study aimed to evaluate the feasibility of meeting this target, identify the materials contributing most effectively, assess implementation challenges, and compare calculated rates with actual recycled content. Two case studies were analysed: the construction of a new residential building and the renovation of an existing one. Data were collected from the bills of quantities, allowing the calculation of total material weight, recycled content according to the regulatory method, and actual recycled content. Results show that the target can be formally met in both cases, with calculated incorporation rates of 88% for the new construction and 79% for the renovation, mainly due to concrete, mortar, and gypsum. However, considering only actual recycled content, significant discrepancies emerged: 4% for the new construction in the lower scenario and up to 40% for the renovation in the upper scenario. These findings highlight gaps between regulatory calculations and real recycled material use, emphasising the need to revise guidelines to ensure genuine progress towards sustainable construction. This study provides practical insights for policymakers, stakeholders, and the construction sector, offering evidence to improve resource efficiency, promote circularity in building projects, and support the assessment of recycled material incorporation per usable floor area through the indicators calculated.