"La Fabrique du Clos"
Basic information
Project Title
Full project title
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Project Description
In 2016, Seine-Saint-Denis Habitat experimented reusing concrete construction to prove that there is a material recovery process for major urban renewal projects.
Four structures were created through the re-use of concrete resulting from the demolition of two social housing builded from the 1960s (a flooring, landscaping or retaining walls and a small construction). The project analysed the technical, economic, environmental and social relevance of this constructive process.
Project Region
EU Programme or fund
Description of the project
Summary
Seine-Saint-Denis habitat and the association of architects Bellastock were awarded in 2016 in a call for proposals entitled “Transformation Architecture in Social Housing”. It promoted the implementation of innovative constructive process for the benefit of the HLM world and the city construction’s actors. The project was supported by Plaine commune and the City of Stains.
Seine-Saint-Denis habitat consequently engaged an experimental project in the Clos Saint-Lazare district of Stains. This was to defend the idea that reuse of materials may have an economic interest, social and environmental benefits for project owners and for territories.
Four structures were created by reusing concrete from the demolition of an R+8 tower and an R+4 building from the 1960s (flooring, landscaping or retaining walls and a ventilated but unheated outdoor construction). We analysed the technical, economic, environmental and social relevance of their replicability in the larger scale of an Urban Renewal programme.
This experiment took place on a wasteland generated by the urban project. In addition to the technical content of the project, the land served to develop temporary events for the local residents.
Key objectives for sustainability
Over the last twenty years, France has engaged in urban renewal plan resulting from the massive construction policy post World War 2. This policy increased demolition and reconstruction program of social housing wich had significant negative economic impact on the building owners, negative environmental impact for territories and social impact on the local residents.
It however created opportunities to experiment the reuse of concrete.
Our objective was to prove the technical and economic viability, as well as the positive social and environmental impact of a new structured approach consisting in local reuse of concrete from the deconstruction. This was against traditional practicies of urban renewal project.
We compared the produced structures with conventional operations. The objectives set for the experiment were to prove :
- 4 technically validated construction processes ;
- The cost of the re-used construction process is at least egual to the cost of a conventional process ;
- The carbon footprint of reuse is greatly improved by eliminating material flows ;
- The reuse operation participates to create a local profesionnal sector favoriting employment reinsertion.
The achievement of these objectives proves the sustainability and the potential replicability of this experiment in large-scale opportunities.
Key objectives for aesthetics and quality
Demolition projects are often associated with construction projects, which profoundly change the image of places. These projects are regularly located on the scale of an entire neighborhood and take place over long periods of time (over 10 years). In this case, residents may feel dispossessed of part of their "home", which can lead to problems of appropriation of the urban rehab project.
The reuse of materials can promote this appropriation by enhancing the memory of the places. However, for large-scale replicability, it’s essential that the news structures have the same technical and aesthetic qualities as standard ones. This avoids the negative feeling that may exist regarding the reuse of materials, sometimes considered like "second-hand" and gives credibility to these actions.
The structures created were the subject of a technical validation, carried out by a project manager (Bellastock) and a certification organism (CSTB). They have been also the subject of a validation carried out by the technical services of Seine-Saint-Denis habitat (for replicability in private spaces), the City of Stains and the Plaine Commune agglomeration (for replicability in public spaces), and also by the residents.
Indeed, the project space was temporary occupied by local associations after the structures were completed. We also organized open construction visits. Both of those allowed us to question the local residents on the aesthetics of the constructions, their appropriation of the reuse approach and to test the use of our structures. In this context, more than 700 local residents visited and used that space in 2016, the year of our project.
Key objectives for inclusion
The results of the project show that reuse can have financial benefits for the owner. But, major benefits are demonstrated on the environmental and social level, for territories and their inhabitants.
Indeed, Seine-Saint-Denis habitat and its partners defended the idea that reuse contributes to the implementation of a sustainable urban project with a controlled carbon impact for the affected areas. This was also vector of local jobs favorable to the professional integration of inhabitants from disadvantaged areas.
The year of experimentation and the production of four prototype structures in concrete reuse had the direct impact of mobilizing 32 employees on integration or training courses over the various construction periods. Indeed, the reuse of materials on site creates a new local activity, which is the preparation of the material for its reuse.
In the specific case of our project, this involved cutting the concrete deposits (partition walls and shear walls) to the expected templates depending on the identified way of reuse (concrete stone flooring, landscaped walls or dry stone support in particular). This activity is carried out on the project site and helps to develop local employment. It can be directly managed by a social and solidarity economy company that carries out construction activities or be integrated into reserved contracts in order to promote local professional integration.
As part of our project, these activities were carried out by the « Régie de Quartier de Stains », which is a local association structure of integration through economic activity that has developed services in construction programs.
Results in relation to category
The Seine-Saint-Denis habitat experiment in Stains proved the technical viability of reusing concrete from the demolition programs of social housing in four types of structures. The deposit used was 8cm non-reinforced concrete partition walls (for the floor covering and low walls) and 15cm reinforced concrete partition walls (for construction).
The technical interventions induced by reuse in deconstruction and construction programs were very simple. They mainly used the technical means conventionally used in these projects, in order to ensure the economic feasibility of the project and to facilitate its replicability.
These results were made possible by the prior analysis of the potential future use of the material to be deconstructed. This study was made by a specialist project manager (Bellastock), who produced a document called "resources" diagnosis. Indeed, this document is essential for the implementation of any reuse project. It guarantees the potential future value of the most relevant forms being reused with regard to the initial qualities of the deposit.
The reuse of materials induces a modification of the traditional way to conduct any demolition or construction programs, by carrying out additional studies (resource diagnosis), the transformation of demolition methods (in selective deconstruction) and the organization of site logistics (preparation of material for reuse by temporary land use). These are the essential steps for the implementation of a circular urban project.
Once completed, they produce a significant improvement in the carbon impact of operations. In the case of Stains, the recovery rate of materials resulting from deconstruction reaches 80% in reuse way. The remaining 20% represent the losses inherent in the implementation of a first experimentation. This value will decrease as the skills of the actors on the subject increase.
So, it’s possible today to envisage demolition programs that would produce 0 waste and serve to construct.
How Citizens benefit
The citizens were direct actors in this experiment. They have been associated in two different ways:
- Future direct user of these programs were invited to visit the site under construction during open days and to practice it during the festive events organized on it throughout 2016.
Indeed, the experimentation area has turned into a living space dedicated to local resident. During the summer, it became an temporary tavern, supporting festive entertainment. During construction time, an half day of open doors in the presence of the workers was organized every two weeks, to discuss the nature and objectives of this experiment.
In one year, more than 700 people were aware about material reuse and were questioned about the aesthetic quality and usage of the works produced. These activities initialy produced skepticism, but they are now the subject of a broad consensus among local residents thanks to this dialogue.
The experimental area is a concrete reuse showroom since 5 years. Seine-Saint-Denis habitat made it very regularly visited to interest professionals. The inhabitants continue to practice it, during the many festive events organized by the residents' association which now manages the place.
- They were also direct players in the site. The reuse of materials creates new activities of « material preparer » before its reuse and « logistic manager of materials » between the demolition and construction site. These activities, managed ultra locally on the project site, allow the development of a social and solidarity economy by mobilizing integration structures through economic activity. On this project, 32 workers on the path to professional integration were directly mobilized to carry out the new activities induced by re-employment.
Innovative character
The recovery of construction site materials is required in the construction world with the support of several circulars from the European Union (example: framework directive 2008/98 / EC of November 19, 2008) or directives from the various member states.
If these policy participate to create or to develop genuine industrial sectors for recycling materials, there are still few reuse initiatives in housing construction programs. However, reuse is at the top of the hierarchy of treatment methods, because it is more environmentally friendly than recycling.
So, our innovation carries the strong ambition to structure a sector for concrete reuse (structural or not) in construction programs, with a strong economic, social and environmental impacts for the territories.
Concrete represents approximately 90% of the waste generated by a demolition operation (by volume). Moreover, it is a material produced from increasingly scarce resources. The environmental stake on the subject is therefore enormous.
La Fabrique du Clos project was implemented with the dual objective of testing the technical feasibility of a constructive process in concrete reuse, as well as of proving its replicability on a large scale with regards to its economic, environnemental and social impacts.
It’s a showroom, which has been visited by several hundred people since its creation, which serves to prove by example the feasibility of this constructive process and participate in the deployment of these initiatives in France. Thanks to this experiment, the local sector is structured, the players increase their skills and the contracting authorities are convinced of the merits of the circular economy approach in construction programs, which allows now replicability in many projects in France.
Through its results, the innovation in this project is technical (reuse of concrete), but also social (job creation), economic (structuring of a sector) and environmental (reduction of the carbon impact of sites).
