Design for Reuse (DfReu) applied to buildings; anticipate disassembly for the End-of-Life (EoL), in order to preserve resources

International audienceThe construction and building industry is the principal emitter of GHG in France with 116 million tons of CO2 equivalent, i.e. 33% of total GHG, according to CITEPA, 2015; and the biggest consumer of material. These emissions have two distinct causes: energy consumption or functional energy (electricity, heating, ventilation, etc.) and energy used during its construction, known as embodied energy (production of materials, transport, site, etc.). The research work presented aims at setting up an infinite cycle of use of materials by their reuse and answering in particular to the problems of circular economy. Structural work and foundations represent the majority of the embodied energy of a building. The research effort is therefore focused on the structural elements. Reuse is here defined as the reuse of an element without transformation, unlike recycling which induces a new industrial cycle of transformation of matter. It is therefore about reducing the consumption of materials and lowering GHG emissions. Reuse is not sufficiently taken into account in environmental assessments and requires new indicators in LCA methodologies. Several considerations are needed to evaluate reuse including: (1) calling the lifespan of buildings fixed at 50 years for the life cycle into question, in order to take into account the different cycles; (2) distinguish the LCA of the building from that of the products; (3) adapt D module from EN 15804 to the very new and not yet professional sector of reuse; (4) new allocation system for both initial deconstructed building and reconstructed second building to benefit from the positive impacts of reuse; (5) integrate the several possible scenarios of second lives for an initial product (same function / downgrading / redirecting, need to be evaluated differently). The missing data identified have to be generated by the relevant stakeholders. In order to reuse these elements to the fullest of their initial capacity, it is important to transfer the necessary characteristics to the future "reuse designer". The design for rebuild methodology we are implementing aims to design the structural elements by increasing the BIM parameters (6D, LCA), to attach the environmental impact, the mechanical information, material durability, ageing to each object of the digital mock-up. We envisioned to install digital and physical traceability (like RFID chips in the material) that makes it possible to follow the evolution of the element over the years and to feed a database in parallel. At the end of its life the database is accessible and searchable for the design of a future building. A development of tools and gateways will then allow from a model of calculation to go to query the database. The objective is to find an element resulting from the deconstruction that can be reused in the future construction. The challenge of this work is to ensure that the element of the database has all the characteristics to meet its new structural function. Next step is to implement the presented methodology on experimentations