Integrated sustainability assessment of construction waste-based shading devices for the refurbishment of obsolete educational public building stock

Buildings and the construction sector are responsible for a considerable share of human environmental impacts, and have high economic and social costs. This project aims to contribute to advancing towards circular economy-based construction techniques, to improve the sector's sustainability performance. Specifically, the project developed a tool to assess the sustainability of waste-based shading devices for public school building stock. The tool combines a multi-criteria decision-making method with the Delphi interview technique to reduce possible biases to a minimum. It is a flexible instrument for holistic sustainability assessment of initial designs. The tool was validated by assessing six initial designs created in three cross-disciplinary university courses. The resulting high economic satisfaction indexes - up to 0.93 on a 0 to 1 scale - and low sustainability indexes - from 0.39 to 0.53 - confirm that four alternatives are economically feasible. However, the environmental and social parameters could be improved. In this first application of the tool, the comparison of recycled and reused construction materials versus new building materials allowed informed trade-offs to be made between the associated embodied and operational carbon, to compare the long-term operational energy and carbon savings of the higher-performing solution with new materials versus the upfront lower embodied carbon of sourcing and applying reused and recycled materials for similar alternatives. Findings on the contribution of reusing materials, with reductions in environmental impacts up to 45%, prove that this project is contributing to defining more sustainable facades.