Sustainable cities: towards an ecological and smart transformation of urban spaces
Technological innovations, circular economy concepts, and new regulations play a crucial role in the development of sustainable cities—a topic that is more relevant than ever and at the heart of the challenges addressed by INTERMAT and its organisers.
Sustainable city, the green city of tomorrow
Discover our new video from our BFM TV - INTERMAT 2024 series: “Ville durable, la ville verte de demain”. An in-depth analysis of the challenges to be met and the solutions to make this new urban ambition a major asset in the building and civil engineering sector's energy transition.
Optimising underutilised spaces: a new approach to urban development
One of the priorities for transforming cities into more sustainable spaces is to optimise the use of existing infrastructure. As Jean-Philippe Trin, Deputy CEO in charge of the Public Works Division at Bouygues Construction, explains :
"The idea of intensifying use is based on the fact that many buildings are only utilised for a small part of the day. Think of car parks, schools, and sports halls
From this perspective, underutilised spaces can be reimagined for mixed uses, such as coworking areas or shared spaces. This approach is particularly relevant in France, where the demand for housing is high, especially in major urban areas.
The optimisation of these spaces is not limited to public service infrastructure but also extends to housing. Concepts such as shared housing, which combine private and communal spaces, are emerging as innovative solutions. According to a study conducted by Insee in 2023, approximately three million homes in France are classified as vacant, representing a significant potential for this type of optimisation.
Redeveloping industrial brownfield sites: an opportunity for green cities
The conversion of industrial brownfield sites is another solution to current urban challenges. These vast abandoned spaces, often located on the outskirts of major cities, offer significant potential to reduce urban sprawl and create new sustainable neighbourhoods. In France, the state has identified nearly 250,000 hectares of industrial wasteland—an area equivalent to several major cities.
One emblematic example is the Les Fabriques project in Marseille, mentioned by Jean-Philippe Trin, where 14 hectares of brownfield land are being redeveloped to accommodate 250,000 m² of housing, schools, and offices, while integrating green spaces. This initiative follows a sustainable urban planning approach, aiming to green up to 40% of these sites, according to Bouygues Construction’s projections.
Urban greening is also a crucial tool in adapting cities to climate change. A study by Ademe* shows that green roofs can lower ambient air temperatures by up to 4°C during heatwaves. In addition to reducing urban heat islands, green roofs can also capture rainwater, reduce buildings’ energy consumption, and provide accessible green spaces for city dwellers.
Circular economy in construction: recycling for better building
The circular economy is another pillar of sustainable cities. As the construction sector accounts for nearly 70% of waste generated in Europe, recycling materials has become a necessity. Jean-Philippe Trin highlights the importance of Bouygues' initiative with its subsidiary Cineo, dedicated to recycling demolition materials such as concrete and steel for reuse in new constructions.
The circular economy not only reduces waste but also lowers the carbon footprint associated with the extraction and production of new materials. A 2022 study by the National Institute for the Circular Economy (INEC) indicates that material recycling could cut CO₂ emissions from the construction industry by 30% by 2030.
Innovations in sustainable construction: towards more efficient buildings
The thermal renovation of existing buildings is essential to reduce energy consumption and greenhouse gas emissions. In France, 43% of total energy consumption comes from the building sector, with older buildings being major contributors. Bouygues Construction has developed solutions such as the Archisop concept, which aims to reduce energy consumption by a factor of three, already anticipating the thermal regulations set for 2031.
According to a study by the International Energy Agency (IEA)*, improving the energy efficiency of buildings could reduce global energy demand by 10% by 2040. These innovations, combined with advancements in construction materials and new insulation techniques, enable the development of sustainable buildings that consume less energy while ensuring greater thermal comfort for residents.
Towards a resilient and connected city
Alongside innovations in construction, the digitalisation and industrialisation of building processes optimise resource management, reduce disruption, and enhance energy efficiency. The adoption of Building Information Modelling (BIM), a 3D modelling system for buildings, facilitates planning and optimises all phases of construction. According to a McKinsey & Company study*, the use of BIM could reduce construction costs by 15%.
Additionally, the development of soft mobility solutions (cycling, public transport) and their integration into construction projects enable the creation of pedestrian-friendly zones in eco-neighbourhoods. The combination of these transport modes improves urban quality of life while reducing CO₂ emissions. Nordic countries, such as Sweden and Denmark, are particularly advanced in this area, with policies aimed at phasing out diesel vehicles and highly developed cycling infrastructure.
The city of tomorrow: a shared challenge
The transition towards sustainable and green cities relies on a comprehensive approach that integrates technological solutions, innovations in construction, and more responsible resource management. The renovation of existing buildings, the redevelopment of industrial wastelands, and the optimisation of urban spaces are all key levers for creating more resilient cities, adapted to 21st-century challenges. The transformation of cities also depends on collaboration between public and private stakeholders to design smart and connected infrastructure while ensuring a better quality of life for citizens.
Sources:*
Insee, study on vacant housing in France (2023)
Ministry of Ecological Transition, industrial wasteland census (2022)
Ademe, study on green roofs and their climate impact (2021)
National Institute for the Circular Economy (INEC), report on recycling in construction (2022)
International Energy Agency (IEA), report on energy efficiency in buildings (2020)
McKinsey & Company, study on the impact of BIM in construction (2019)
Study on soft mobility in Nordic countries, European Cyclists’ Federation (ECF) (2021)