Pierre Veltz, French territorial economist (https://www.lemonde.fr/economie/article/2020/03/30/les-usines-reviennent-en-centre-ville_6034840_3234.html).
Industries were/are considered as a source of pollution and noise for inhabitants and the built environment. With the development of the territorial circular economy concept, some types of production are returning to urban areas like food industries via the urban farms. The principle of urban agriculture is very relevant for illustrating an intensive need of new production activities in urban areas.
Material production had gradually disappeared from the cities, in favour of service activities. For economic, social or urban reasons, initiatives aim to maintain or attract productive activities in the city.
The local production will have an important added value for cities. It might impact the metabolism of the city and also increase the attractiveness and the local economic development. On a narrow ridge between industrial innovation and local innovation, Earth Cycle is interesting from conceptual and philosophical point of view! Earth Cycle demonstrates also the innovation capacity of the construction sector, which is well known for its lack of creativity.
Brief presentation of the technical process of Earth Cycle
This process and the production of the factory were developed in Journal 1 of Earth Cycle and this paragraph presents the main characteristics of this process. Figure 1 shows the process and it is implementation in Earth Cycle factory. In fact, it is not an artisanal approach; it is a real innovative industry producing 3 categories of materials with 3 production lines.
Earth Cycle is a unique example. A production of local construction material with 3 different properties and lines inside the city and transforming a waste to a resource. For circular cities, this concept could be a model or a major contributor for circular cities concept.
Economic and sustainable issues
The idea of using available waste and transform it to a resource is one of the key elements of circular economy. But the temporality of needs and availability of earth are not the same. In fact, transforming waste might not be in harmony with the immediate needs of the construction sector. Earth is available at the time of the excavation, but most probably not needed immediately for the construction in the same area. This temporal lag is important and has to be managed. In fact, the storage, transportation and business model have to be considered and analyzed. This is a major concern for future researches.
Earth Cycle is a prototype for pooling the reuse of soil on a territorial scale. However, as the amount of earth mobilised from excavation is important, the Sevran plant will have to be duplicated in the future. This replication issue was discussed in detail in journal 2.
This is the essence of the approach and its inclusion in a logic of reuse and circular economy. The situation also requires having on the same site, or at least within the same limited perimeter, the construction site and the site dedicated to sorting, storage and the production line.
It is also important to talk about the quality of the earth, its humidity, granularity, while at the same time other physical and mechanical aspects have to be investigated. For example, in the Paris region, only one category of soil (Silt Platea: Limon des plateaux in French) is useable for the production of earthen materials.
The availability of this soil is therefore dependent on circumstantial conditions, on opportunities which, if they are not rare, constitute contingencies which prohibit the strictly industrialist model.
This apparent simplicity of Earth Cycle and the fact that rammed earth are ancestral techniques should not mislead: the basic constituent elements of the constructive system are themselves new (extruded panels or compressed bricks), but in a more general way there is a design and engineering work upstream of the construction site which requires finding the best possible match between a raw material, the constituent elements of the construction system (panels or bricks), methods of implementation compatible with them and the economic conditions and human resources of the future site.
The incentive and legal support
The technical and financial uncertainties, leading for example to the abandonment in the first phase of the project of panels made of extruded material (main technological innovation) to stick to Compressed Earth Blocks (CEB / BTC in French), were important. The technology transfer from laboratory to field is not an easy task. More detailed analysis of these constraints are presented in journal 4.
The fact that this production of elements (separate from the construction of the building) must be done in a dedicated space, on site or nearby, and the fact that the location and area of this space partly determines the production conditions, completes the general design of the approach which until the end presents the two sides or if one prefers the two registers of innovation. Talking about a ridge allows us to insist on the fact that it is an unstable situation that can go sometimes to one side, sometimes to the other.
At this stage Earth Cycle is a prototype and an innovation but the replication is mandatory if we want to reach an integrated territorial circular economy for earth management at the scale of the Paris Region. It is also important to mention that the legal framework and incentives coming for the French government and local authorities offer important perspectives.
- For building permits to be submitted from July 1, 2022 (French Law Resilience and Climate, https://www.ecologie.gouv.fr/loi-climat-resilience) :
"... Integration of raw earth materials mainly from excavations and without the addition of binders, with the exception of bio-sourced stabilizers, at a minimum of 0.025m3 per m² of floor area is requested. For housing, this is equivalent to an average of 1.5m3 of raw earth materials per dwelling".
- For building permits to be filed from January 1, 2026 (same law) :
"... Integration of raw earth materials mainly from cuttings and without the addition of binders, with the exception of bio-sourced stabilizers, up to a minimum of 0.05m3 per m² of floor area is requested. For housing, this is equivalent to an average of 3m3 of raw earth materials per dwelling".
Innovation is an iterative process
However, one doubt remains: most urban experiments in ecological transition are designed to be geographically and temporally limited, if only to demonstrate their operational efficiency. But could it be that they do not upscale? This is the question addressed by certain researchers wondering about the multiplication of experimental niches and ending up by describing a regime of permanent experimentation, a "generalized experiment" whose object is no longer so much to transform the processes rather than constituting a new form of city governance.
Towards a new art of building in the 21st century?
Earth Cycle opens new perspectives. The European Union has just launched a program, or rather a creative and interdisciplinary movement in the field of construction and including architectural design for “aesthetic, sustainable and inclusive” places. This is not a competition but (at the time of writing) a program for discussion and co-design. It is called "New European Bauhaus" - the reference is evocative.
The term "New Bauhaus" is like an invitation to invent an art of building bearing a new modernity, to invent the vernacular architecture of tomorrow, that which, based on resources available first locally, exploited by means of accessible and non-polluting technologies, can initiate a new art of living and building.
It seems to me that a design and a territorial economy of construction using inert earth from excavations can serve this objective quite well. Better: they can constitute examples and emblems alongside other formulas that are also part of the art of reuse and acquire the status of global innovation, of those that make us pass, to use the formula of Frank Geels (University of Manchester), from one socio-technical regime to another.
In my opinion, Earth Cycle future is actually uncertain. If the context seems favorable today (the ideas of short circuits and reuse are on the rise; there are risks of shortages in building materials or at least tensions in their supply, etc.
If the uncertainties around national and European regulations and techniques seem to be rising, nothing allows predicting whether this first experience will lead to something other than itself. Will Earth Cycle be the start of a dissemination? or even a generalization? or will it even take place? These replication and upscaling requirements were detailed in journal 3.
But the question is less that of “if” than that of “how”, namely the model it will follow. This is no longer a question of the technical-organizational model but of the territorial and economic model.
The special place of the community
Several elements can come to question this destiny according to a model other than purely competitive and commercial. The approach can only be competitive, when certain conditions are met. But could this apparent weakness not turn into an asset in a different perspective of deployment?
The presence of the community, which does not only intervene as a bearer of the investment but also as a guarantor of the project, and the spatial alienation of the project invite us in particular to examine the substantial character of the territorial and urban dimension of the innovative dynamic. We could add to this the strong presence of developers and the creation of a Cooperative Society of Collective Interest (Société coopérative d'intérêt collectif – SCIC in French), to bring together the entire consortium in the operating phase, which is a form of cooperative allowing a local authority (person moral) to be part of it.
The idea of experimentation in vivo on an urban scale carried out by a municipality or an inter-municipality can bring to mind the notion of “living lab”. Many French communities have taken over the expression, for which the outlines are blurred. The living lab sometimes designates a project, sometimes a methodology centered in both cases on open innovation and cooperation with the users from the design stage to the deployment of new services.
Community involvement is of a different order here and citizen or resident participation is not at the center of the innovation undertaken.
The community's commitment should rather be analyzed within the framework of the reflections carried out on the new forms of public action marked both by the need to engage in the ecological transition but also and above all, by the uncertainty as to the relevance of the paths chosen. Indeed, for this reason, we see the development almost everywhere in Europe and in the industrialized countries of a "governing by experiment", of which one of the observable characteristics would be precisely the involvement of local authorities and the rupture with the old forms of planning.
For that, it is perhaps necessary to stop reasoning exclusively in terms of economy of sector for which space is only a secondary instance (it is what it is necessary to free oneself from) to enroll in a logic of territorial ecology where the value proceeds from the integration on the same territory of the actors, the skills and the resources, being part of a local productive system… of the building! The notion of local productive system is not new either. But related to the building, in other words to real estate (therefore not mobile), it changes its nature and makes it exist in a "local consumer system".
Earth Cycle is a prototype for a new approach of circular economy for the construction sector. But it is also a major industrial innovation allowing the return of activities to urban areas and creating local economic development.
This return of industry to the city is a major challenge if productivity is to once again become a structuring element of the sustainable city. This economic aspect is fundamental to the cities of tomorrow.
Earth Cycle is also based on innovative circular economy concepts. This is an important element of the environmental component of the sustainable city concept. So, shouldn't we be considering the circular economy as the spearhead of tomorrow's sustainable cities? Earth Cycle is a promising example...
This reflective text is inspired by the work of P. Veltz and F. Menard about industries, territories and innovations. This topic is crucial for an urban sustainable development by integrating metabolism and circularity.