Journal 3 Earth Cycle

 In Journal 2 of the Earth Cycle project, we insisted on the fact that Paris Region produces around 30 million tons of DCW (Demolition and Construction Waste) per year, including 25 million tons of inert waste, including around 18 million tons of excavated earth per year. The creation of the infrastructures of the Grand Paris Express (GPE) and the town planning operations linked to it will generate even greater production in the coming years: it is expected that 60 million tons will be generated by the Société du Grand Paris (SGP) by 2030. These volumes demonstrate the need for the development of research and innovation actions on a regional scale but also implementation strategies on large scales have to be discussed and elaborated.

This important volume of earth (i.e. four Pyramids of Khufu), must be extracted, transported and valued in a smart and sustainable way. This topic seems to have been completely neglected in urban planning and urban development for the past 30 years, with some exceptions, while it used to be a part of the spontaneous regeneration of urban spaces in the previous periods, as mentioned before. Earth Cycle is an active contributor in an attempt to implement circular economy logic in urban planning. The actors mobilized around this action offer this possibility.

The objective of this journal is to discuss Earth cycle duplication and scaling up strategies in an attempt to address the problems regarding excavated earth management in the Paris Region. Developing an approach to use these soils as a construction material is a large contribution in the development of circular economy in the Parisian region. The duplication of the pilot proposed and implemented by the Urban Innovation Action’s project in Sevran is a major issue for the coming period. Scaling up a pilot is an important element of the success of the UIA project.

The choice to deal with this theme was naturally necessary because the UIA Earth Cycle ends on 10/30/2021 and one of the perspectives to be implemented would be the duplication of the pilot in other territories. This journal analyzes this perspective and the strategy proposed through actions of promotion, communication, dissemination of knowledge but above all the development of the factory and the cooperative society.

Earth Cycle proposes to reuse and to valorize the excavated earth to produce building materials with low environmental impact. A raw earth materials factory located in Sevran was designed and built. This factory will produce from autumn 2021 blocks of compressed earth, mortars and coating.

During the UIA project, many initiatives to organize the earth construction sector have been revealed necessary in parallel with the construction of the factory, so that the pilot finds its place in a local ecosystem first then towards a regional scale. These actions relate to three major categories:

• Technical Certification of materials’ performance.
• Calculation of their ecological footprint for integration in a Life Cycle Assessment. Three documents of an Environmental and Health Declarations for masonry walls and coating were elaborated.
• The training of architectural professionals and the building sector to the use of materials.

The creation of the Sevran pilot factory is only a first step. The purpose of the UIA project is to test an innovative solution, by creating a knowledge base and skills, in order to then be able to generalize it. The figure 1 proposed by the Earth Cycle team, demonstrates the need of 30 production sites on the scale of the Parisian region. This estimation is based on two criteria; the potential estimated by local authorities and urban developers from one side the availability of construction materials. In this journal, we discuss these models and options.

 The figure shows the map of the Parisian region and an estimation of the market potential for earth construction.

The current dynamic of the construction sector for circular economy in the Parisian region, marked by an increasing number of local initiatives, support from the metropolitan authority Grand Paris and the Region Ile de France, requests from developers and the development of production chains, will allow major progress in the years to come. This is a very positive context for a UIA project like Earth Cycle.

In fact, the Sevran project is achieved and the factory is realized and the business and governance model, is established through the creation of a cooperative company. Earth Cycle has succeeded in setting up an ecosystem around earth construction, which will have to be developed. The choice was made to be in a cooperative and not in a competitive process!

Even if the valorization as construction materials will not concern all the excavated earth in the Parisian region, the intelligence lies in the multiplication of valorization solutions both in construction but also in landscaping, in infrastructure, etc.

It is essential to seize this resource opportunity to rethink our building production methods. History shows us that it is possible. This issue was discussed during a conference in June 2021 entitled Urban soils a positive value for the cities of tomorrow. The two co-managers of Earth Cycle presented the project achievement and also the integration of the earth as a construction material in a larger scale of valorization (https://youtu.be/PPUw2aaUHZ4). 

 To strengthen this dynamic, it is necessary to:

• Rely on the existing earth excavation management channel, which has considerable potential for extraction, transport and sorting capacity;
• disseminate and use the knowledge of earth construction architecture by teaching it even better in engineering schools in order to facilitate the integration of this material in projects;
• continue research into production processes;
• fund research on designs adapted to the constraints of the material, but also to deconstruct prejudices and remove regulatory obstacles on the use of earth construction.

There are good reasons to study urban innovation and pilot implementation from a systemic perspective. A key finding in innovation research and social sciences is that organizations rarely innovate in isolation, but in interaction with clients, competitors, suppliers, and other organizations. This relation between the Parisian ecosystem of earth management is one of the major achievements of the Sevran pilot project. Indeed, there is a serious will to develop the pilot and working together for a systemic approach for earth management and earth construction.

This system perspective was useful in understanding and analyzing these interactions. The urban innovation system approach elaborated during Earth Cycle conceptualizes the city or urban region as a context in which innovations emerge from complex interactions between urban actors — firms, citizens, local authorities, universities and research institutes — in a particular institutional setting.

Innovation processes are much more complex and diverse, influenced by multiple actors that interact in networks with feedback loops, and involving many types of knowledge beyond scientific knowledge. Studies on urban innovation systems seek to explain how innovations emerge in an urban context, why urban regions differ in their innovative performance, and also address questions on the governance and management of such systems. Studies in this field draw from a variety of disciplines including economic geography, urban and regional economic, political sciences, innovation studies, social sciences, and urban planning.

Reconciling needs, demands and supply is an important issue in developing the implementation of an innovative system like Earth Cycle and it is a fundamental element for the success of an innovation. Creating the market and demonstrating that innovation fits into it is the crucial element towards duplication and scaling up.

According to a recent study by the Paris Urban Agency, 33 million square meters will be built or rehabilitated over the period 2025-2030 in the Greater Paris area. To start integrating the raw earth in urban construction, a first strong initiative would be to integrate 0.025m3 of earth materials per m² of floor area. On average, this represents approximately one to two partitions per apartment. By applying this realistic ratio, for example, for housing, one to two partitions per dwelling, at 20% of these constructions, then 30 production sites of the size Earth Cycle would be needed. This very summary and preliminary analysis shows the need for about 30 similar Earth Cycle factories in the Paris region. This number is indicated on the top of figure 1.

 In order to facilitate the realization of new factories in other territories, the following elements must be considered so that the concerned cities and territories join this approach and will participate in the development of Earth Cycle. The sensitization on these elements will facilitate the duplication.

• Job creation and training: The implementation and realization of a mechanized production allows job creation on site but also off-site for the stakeholders involved in the earth construction sector (installation, implementation…).

• Improving of urban local metabolism: By managing locally their excavations, constructions and their local processing, soils and earth materials contribute to the decrease in urban flows especially those dedicated to transportation.

• Local circular economy strategy for material management: Soils and excavation management are a part of a local circular economy project especially in new towns and suburbs having an important rhythm of urban development projects. The used materials are coming from excavation in construction sites. They are then transformed into materials then used in the building construction. It is important to know that this process is from cradle to cradle as for construction by using earth, no adjuvant is necessary.

• Green building: Earth materials are a good regulator hydric and have qualities thermal inertia allowing reducing the energy consumption. In addition they do not release organic volatiles compounds (VOCs) and participate therefore to the quality of indoor air. Figure 2 shows the certified materials proposed by the Sevran factory.

• Local Economic Development (LED): The excavated earth is transformed to a construction material and used on a limited territory. This approach creates local economic development. The territory is in fact a key link between development actors like investors and developers of the sector and socio-ecosystem coordinator.

5 major criteria to ensure the success of the replication is proposed by Earth Cycle:

 The raw material: Use embankment land, and not quarry lands, to maximize environmental benefits, by selecting suitable earth to use as a construction material on the basis of environmental criteria and mechanical criteria.

The classic soil studies will be enriched with some parameters. Investigation and core samples will be updated provision of an earth expert to perform tests. It is important to push aside any suspicion of pollution.

To keep it simple or an easier scaling up in the Parisian region, the used earth in Sevran is the silt. This category of soil is available in many areas of the Parisian agglomeration. Starting from the same resource will make possible to achieve important savings in terms of material certification and assessment. This element is very important for the duplication.

A place of storage, drying and preparation of Earth: The homogeneity of the resource is essential for control production quality and validity of certifications obtained especially if the used silt is from the same category as Sevran. This issue requires building up important substantial stocks to avoid testing frequently new formulations.

The current process for Earth Cycle in Sevran plans for a stock of excavated earth to be done once a year, at the end of summer. This imposes a capacity to earth storage. In addition, the natural drying chosen by Earth Cycle involves storing the earth under a covered building for several months before use.

Whether or not it is linked to the site of production, a storage site of at least 5000m² must therefore be planned. This place will also be used for carry out preparation operations soil (crushing, sifting, generating nuisances during preparations (1 to 2 sessions of a few days per year).

Another possible option for the drying would be to implement the storage site next to a production unit which releases fatal heat which will be reused for heating. This will give meaning to an integrated urban planning through a Nexus-type approach proposed in our first journal.

A production and sale place: Based on the Sevran experience, these two functions can be easily be integrated into urban areas in comparison with the storage and preparation part. The production site, based on the experience of Sevran factory, must be at least 2800m.

As in Sevran, it can be located near other buildings by respecting the level of noise, which may involve acoustic treatment of the building. The architectural and its integration into the landscape are also key elements of acceptance of this site by the inhabitants. 

Another option could be explored in future development, it is related to a potential implementation of mobile lines that take smaller places but probably need more technological development. Figure 3 shows the integration of the Earth Cycle factory in Sevran.

Products and constructive systems: A consistent choice of products with the available earth resource, production methods and storage is necessary. Thinking products according to their potential implementation and use is also an important criterion. The factory can propose small precast elements, poured earth, etc. Earth Cycle in Sevran produces compressed earth blocks, plasters and later on panels in extruded earth. These three different construction systems are already certified by French national certification agency.

The business model and the local context: in Sevran, the partners of the project decided to create a cooperative company but other models could be possible if the local authority is willing to have a direct management of the project or a Public Private Partnership system. These elements are important and the pilot of Sevran supported by UIA opened many potential options. These options will be discussed in the next journal.

At each stage of the project, the Earth Cycle team made choices: on materials, drying and land preparation and material production. At each of these stages, other choices could have been made. Also in the context of duplication, it is advisable to ask at each step, what the best choice is that suits to the local context. The figure 4 resumes the different steps of the pilot implantation and functioning in Sevran. The steps : 1- Extraction of soils, 2- Storage and Earth preparation, 3- Construction process ( the fabric), 4- Use of Earth Cycle Production in a building project.

A shift towards a more Circular Economy in the construction sector is crucial to achieve a more sustainable and inclusive built environment that meets future demands. Circular Economy is a promising concept for industry and society. If implemented well, Circular Economy can deliver environmental benefits and economic advantages for which innovation is essential.

The management of earth excavation is often a forgotten topic in the territorial circular economy approach. To achieve a resource-efficient built environment, Circular Economy principles should be developed and implemented systemically and on large scale, going beyond cities. This is the topic of this journal dealing with duplication and upscaling of the UIA Earth Cycle.

To realize this, local authorities, citizens, and other stakeholders need a collaborative and science-informed decision environment that allows for developing different waste and resource management options, and assessing their impacts on the environment, spatial quality and quality of life.

Earth Cycle is a very successful initiative as the different analyses presented in this journal show. In fact this pilot has an important potential of development. It is integrated in a strategy for an integrated earth management on the regional scale and also the duplication potential is very important and the key for success are under control as the local authorities are interested, the urban developers are motivated and the research to improve the technical elements is still continuing through a high level of research and development.

Earth Cycle delivers solutions and strategies for a circular economy in urban planning throughout Europe, focusing on sub-urban locations. This pilot in Sevran introduces a methodology to create strategies with local stakeholders for earth valorization. In the next steps focusing on governance for the shift towards Circular Economy on regional level is important. In fact transferring circular strategies and solutions from one location to another is very sensitive issue.