Piloter la circularité des flux de matières et composants du bâtiment en favorisant le réemploi

Managing the circular flow of building materials and components by promoting reuse

• Auteur / Autrice : Thibault Ronzaud
• Direction : Bernard Yannou
• Type : Projet de thèse
• Discipline(s) : Génie industriel
• Date : Inscription en doctorat le 08/01/2024
• Etablissement(s) : université Paris-Saclay
• Ecole(s) doctorale(s) : École doctorale INTERFACES : approches interdisciplinaires, fondements, applications et innovation
• Partenaire(s) de recherche : Laboratoire : Laboratoire Génie Industriel
• Partenaire(s) de recherche : Equipe de recherche : Ingénierie de la Conception
• Partenaire(s) de recherche : Référent : CentraleSupélec

Mots clés

Mots clés libres

Plateforme

Réemploi

Bâtiment

Territoire

Platform

Reuse

Building sector

Territory

Résumé

Le secteur du BTP, générant à lui seul 76% des déchets des activités économiques en France chaque année, soit 213 millions de tonnes en 2021, est confronté à des défis majeurs en matière de gestion des déchets et d'économie circulaire. Alors que le gros œuvre représente 19% de ces déchets, avec 31 millions de tonnes, et le second œuvre en constitue 12,2 millions de tonnes, la valorisation de ces déchets reste disparate. Si les déchets inertes bénéficient d'une valorisation allant jusqu'à 70-76%, les déchets non dangereux, notamment ceux du second œuvre, sont moins bien valorisés, malgré leur potentiel de réutilisation et de réemploi. Pour répondre à ces enjeux, la loi de transition énergétique fixe des objectifs ambitieux, notamment celui de valoriser à 65% les déchets non dangereux d'ici 2025. De nombreuses initiatives voient le jour pour promouvoir le réemploi des matériaux de construction, tel que le projet Cynéo, qui vise à structurer l'offre en matériaux de réemploi. De plus, le CSTB développe des outils tels que le modèle BTPFlux pour quantifier et anticiper les flux de matières dans le secteur du bâtiment. Cependant, des défis subsistent. Il est crucial d'améliorer le calcul du potentiel de réemploi des matériaux et de produire des indicateurs fiables pour soutenir les décideurs dans leurs stratégies d'économie circulaire. Ainsi, deux questions de recherche émergent : Comment analyser de manière approfondie le stock de composants dans un parc de bâtiment et sur un territoire, en utilisant des indicateurs de circularité adaptés, notamment ceux liés au réemploi ? Comment accompagner les décideurs, tels que les collectivités territoriales, les aménageurs et les porteurs de projets de construction, dans la définition de stratégies d'économie circulaire ou de plans d'actions adaptés à leurs contextes spécifiques ? En répondant à ces questions, il est possible de favoriser une gestion plus durable des déchets dans le secteur du BTP et de promouvoir une économie circulaire plus efficace et responsable.

The construction sector alone generates 76% of the waste from economic activities in France each year, amounting to 213 million tons in 2021. The building sector accounts for 19% of this waste, with 31 million tons for the structural work and 12.2 million tons for the finishing work. These wastes are valorized to the extent of 70 to 76% for inert wastes, which constitute the majority of structural work waste. However, valorization is much lower for non-hazardous waste, particularly for finishing work waste. European directives set a valorization target of 70% by 2020. This target was achieved thanks to the valorization of inert wastes, which represent the majority of construction waste by mass. However, a significant portion of this valorization is due to quarry backfilling, whose environmental benefits are limited compared to recycling or reuse. Additionally, non-hazardous wastes are mostly underutilized or not valorized, despite their greater potential for reuse and recycling. To incentivize better valorization of these wastes, Article 70 of the Energy Transition Law aims to valorize 65% of non-hazardous wastes by 2025. Several emerging initiatives have been launched around valorization platforms that collect, recondition, and reuse building materials and components from deconstruction sites. For example, the Cynéo project brings together Bouygues Bâtiment France, a developer-constructor, Premys, a Colas subsidiary specializing in deconstruction, and reuse sectors to share, structure, and develop the supply of reused materials. This is an attempt to consolidate reuse flows of materials and components by addressing issues such as guaranteeing material sources, outlets, developing collection and reconditioning processes, logistics, cost control, quality assurance, and training and support for future sectors. To support the construction sector and territories in the field of circular economy and waste valorization, the CSTB is developing several methods and tools, including the Building Material Flow Analysis model named BTPFlux. This model aims to quantify and anticipate material flows associated with changes in the building stock based on an estimate of material stock. The model relies on a detailed characterization of building components and products, equipment, materials, and waste (PEMD) generated by their total or partial deconstruction (e.g., in the case of renovation). This model is based on two other tools developed by the CSTB: the National Building Database (BDNB), which integrates a large amount of information for each building in mainland France, and TyPy, which is a database of building components and a tool for estimating a building's materiality from partial information. Although usable, BTPFlux still requires numerous developments that can be divided into two main categories. Firstly, improving its calculation engine, including integrating the reuse potential of PEM and improving the reliability of estimating the quantity of PEMD for finishing work elements. Secondly, producing reliable and relevant indicators and decision support functionalities for territories, developers, and construction project leaders. Indeed, circularity indicators such as reuse potential, domestic material consumption, and material recyclability rates can be integrated into the BTPFlux model to allow for a more detailed characterization of the building stock. The BTPFlux model could support territory stakeholders such as local authorities in better defining their circular economy strategies and managing their actions (or development projects) based on measured indicators. Thus, two research questions can be formulated: 1. How to analyze the stock of components present in a building stock and within a territory as finely as possible using adapted circularity indicators (especially for reuse)? 2. How to help decision-makers (local authorities, developers, and construction project leaders) define the most suitable circular economy strategy or action plan for their specific contexts? By addressing these questions, it is possible to promote more sustainable waste management in the construction sector and to promote a more efficient and responsible circular economy.