The circular economy: an integral part of contemporary urban planning

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Designing a new district in 2024 necessarily means meeting the requirements of the climate transition by reducing waste, reusing materials as much as possible and encouraging numerous cycles in the use of wastewater and other resources. These and many other examples of the circular economy are guiding the urban planning of the Belval and Metzeschmelz districts, as explained by three AGORA colleagues: Alexandre Londot, Director of Operations; Yves Biwer, Director-Coordinator Metzeschmelz; and Pierre Karst, Project Manager Engineer.

What is AGORA’s vision of the importance of the circular economy in ur-ban planning, and how is this vision put into practice in day-to-day operations?

Alexandre Londot, Director of Operations: “The circular economy has become a pillar of AGORA’s vision and philosophy, and we incorporate its principles into most of our developments. The aim is to create sober and sustainable neighbourhoods by avoiding unnecessary expenditure on building materials. The main priorities for action include the reuse of materials, the use of recyclable materials and other aspects such as the treatment of grey water, the production of renewable energy and, in general, the transformation of waste into resources. It is essential to consider all materials as resources and to challenge old building practices. Our best tool for achieving this integration is to include circular economy criteria in specifications, thus from the earliest planning stages of a development. The circular economy is becoming an increasingly important criterion in our tenders.”

Can you share specific examples of how AGORA has successfully integrat-ed the circular economy into the Metzeschmelz project?

Yves Biwer, Coordinating Director Metzeschmelz: “As part of my job, I have to lead the efforts of all the teams to effectively integrate the principles. The Metzeschmelz site is designed to be almost entirely circular, in particular through the Symbiosis concept, which sets out the principles at every level, from energy supply to wa-ter recovery and waste processing. Among other things, the plan calls for rainwater to be recovered and reused in toilets, and for waste to be transformed into materials to create biomass. The circular economy is at its best when everything has been designed as deeply interconnected, intelligent networks, and that’s what we’re preparing for in Metzeschmelz”.

Pierre Karst, project engineer: “If I had to cite just one very specific example of the circular economy recently implemented at Belval in the construction of Central Square, I would name our initiative to reuse slightly contaminated clays.This enabled us to reuse them instead of treating them as waste. We treated 30,000 cubic metres of clay with lime, which made it easier to keep it on site and avoided having to dispose of it. Such an operation would have required 300 lorries making round trips, which would have been harmful to the environment. We were also able to avoid clogging up Lux-embourg’s landfill sites. This is just one example of how the circular economy really does apply to all urban planning and logistics decisions.”

Alexandre Londot: “At Metzeschmelz, we could cite as an example the idea of using old concrete by crushing it for the construction of pavement structures. On a former industrial site like this, you inherit a significant past and a lot of materials that should be reused as much as possible.”

So, it also shows that the circular economy is based on the use of a variety of techniques and methods, and even innovative technologies, which means that AGORA is always at the cutting edge?

Pierre Karst: “Indeed! We have to keep abreast of the latest research and apply the most advanced techniques. This is true when it comes to servicing the land, as in my previous example, and it’s true at every stage when it comes to all the anticipated uses of the site.”

Yves Biwer: “Another example: studies are underway to assess the feasibility of using geothermal energy at the Metzeschmelz, i.e. using heat from the subsoil, which could be transformed into usable energy for the site. Technologies exist at different stages of development, and we don’t always need sophisticated machinery to achieve our circular economy objectives. We work with a balance of cutting-edge technologies and more traditional techniques. At this stage, we are studying whether the geology is sufficiently favourable to be able to use these thermal sources, particularly deep geothermal energy.”

What are some of the challenges involved in applying the principles of the circular economy to a large-scale project like Metzeschmelz?

Alexandre Londot: “We need to get rid of our old silo-based ways of designing. The circular economy requires us to think holistically about all aspects of urban planning, architecture and engineering. Each aspect must always be considered in dialogue.”

Pierre Karst: “It’s important to remember that there is a scale that defines the order in which a resource should be treated. First, we try to reuse it for the same purpose, that’s reuse. Otherwise, we try to recycle it, then recover it. As a very last resort, if none of these options are possible, we can consider disposing of it. Following this scale is not yet a well-established reflex in urban planning and construction. It’s a learning process that needs to be continued and developed.”

Yves Biwer: “I would also say that, to ensure that everything runs smoothly in the future district when it is inhabited, the active collaboration of future residents will be essential. The adoption of certain behaviours and collective participation will enable the resources made available to be used to best effect. It’s important to raise awareness among residents so that this vision becomes a reality.”

Urban gardens, smart cities, eco-neighbourhoods or temporary occupation of urban space, Through the voice of experts, “Tell me more! ” is a series that explores new trends.

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