In the heart of the ‘Western Crescent’ of Paris

When Renault – whose history is closely tied to Boulogne-Billancourt – decided to halt its production lines, a national interest project was launched. Following years of studies and plans that never came to fruition, the city of Boulogne-Billancourt established the Rives de Seine cooperative development zone (zone d'aménagement concerté, ZAC). This 74-hectare zone encompasses three development areas: the Pont de Sèvres quarter, Île Seguin, and the Trapèze quarter. The overarching ambition is to offer residents and users a model living environment, emphasising mobility, diversity, architecture, landscape design and environmental stewardship.

Located in the Trapèze quarter (named for its distinct trapezoidal shape) is METAL 57, a preserved relic of Renault’s industrial era. Recently reimagined by Dominique Perrault, this building now hosts employees of BNP Paribas Real Estate.

This thriving western Paris hub is also home to leading companies such as Roche, Ipsen, Boursorama, Michelin, Carlson Wagonlit and Vinci. Positioned strategically between Paris, La Défense and the Plateau de Saclay, the area is exceptionally well-connected. The Trapèze quarter benefits from immediate access to Metro Line 9, Tramway T2, and the upcoming Line 15 of the Grand Paris Express, set to open in 2025.

The Trapèze eco-district is reaching the final phase of its transformation with the development of the D5 block, a joint development project between BNP Paribas Real Estate and Eiffage Immobilier.

Building the city of tomorrow

Nestled between Billancourt Park, Quai Georges Corse and Allée George Askinazi, the project seamlessly integrates urban and natural elements. Future buildings are arranged around three walkways connecting the park to the Seine, enhancing the block’s greenery.

Designed by four prestigious architectural firms – Chartier Dalix, BIG, ECDM and AAVP – the project ensures architectural harmony with features like extended balconies and green rooftops.

NEW R building

Lot 1 has been entrusted to Chartier-Dalix, a firm renowned for numerous other projects in the Ile-de-France region (housing on Ile Saint-Denis within the Olympic Village, a logistics hub in Vitry-sur-Seine and the new Grand Paris Express station in La Courneuve). This New R project marks the Renault Group’s symbolic return to its roots.

By 2026, thirty years after closing its factories in Boulogne, Renault will move into new headquarters in a contemporary setting boasting 25,000 m² of office space. The lower floors will feature a plinth wrapped in planted balconies providing privacy and cooling for the building’s occupants. On the upper levels, the office floors will be clad in double-glazed skins for an exceptional panoramic view of the Seine and Paris.

New R will offer its tenants a wide range of services, including a grand, meticulously decorated lobby, an auditorium, a fitness centre, a business hub, varied catering options, hanging gardens and a landscaped walkway linking Allée Georges Askinazi and Quai Georges Gorse.

X Work building

Designed by Danish architects Bjarke Ingels Group (BIG), the firm behind Google’s Mountain View campus in California, the building of lot 2, named X Work (in honour of its iconic silhouette) offers over 15,500 m² of new offices bathed in natural light.

Quality of life and eco-design are at the heart of the project, which features planted areas accessible from every floor: the higher the floors, the greater the façade recesses, creating green spaces for employees to enjoy. On the top floor, an almost 1,800 m² tree-lined rooftop with a belvedere greenhouse embodies the project's biophilic approach.

This emblematic operation has already won over RCI Banque SA, Renault Group’s banking subsidiary, which recently announced its move to X Work.

• Lot 3, designed by Paris-based AAVP, is a 6,400 m² residential project comprising 88 units spread across ten floors. Meeting stringent environmental standards, the project incorporates walkways on either side of the building, designed as undergrowth in connection with the adjacent park, in the private gardens of the ground-floor apartments, in the long balconies on each floor and in the green roof accessible to residents. The project also features two agricultural greenhouses for communal activities to foster a connection with nature.
• Located at the tip of D5 block, lots 4 presents a triangular building with one side looking over the Seine, another facing the park and the third flanked by a planted walkway. With 88 apartments over 6,400 m² of space across nine floors, the building is structured in layers, starting with a green, tree-lined atrium in the ground floor lobby. A patio connects the upper floor apartments to the park, The apartments feature large windows and extensive outdoor spaces, offering a very high quality of life. A rooftop garden provides a shared space for community interaction.

The first parts of this new sustainable city are scheduled to be ready from March 2026.

From offices to a higher education institution

Originally built in 1973, the building at 85 Rue du Dessous des Berges in Paris’s 13th arrondissement was acquired by BNP Paribas REIM in 1979 for its France Investipierre SCPI. The 1,700 m² office space is starting a new life as a 2,100 m² higher education institution. Nestled in a vibrant, mixed-use neighbourhood, the building offers students an ideal location, surrounded by educational institutions and public transport links.

In collaboration with Bouchaud Architectes, BNP Paribas REIM is spearheading this ambitious renovation that embodies the concepts of sustainable and resilient real estate. As a full-scale testing ground, the building will become a showcase of eco-conscious design. This reinvented educational space encourages a sustainable future.

In collaboration with Bouchaud Architectes, BNP Paribas REIM is spearheading this ambitious renovation that embodies the concepts of sustainable and resilient real estate. As a full-scale testing ground, the building will become a showcase of eco-conscious design. This reinvented educational space encourages a sustainable future. To meet the requirements of a public-access building (Category 3), the project focuses on three core commitments:

• An eco-friendly, dedicated building
• Minimal environmental impact
• A low-carbon, low-tech approach.

Once complete, 85 Rue du Dessous des Berges will be able to accommodate up to 500 people (students and staff).

A reinvented, flexible and future-proof building

The renovation works focus on transformation rather than demolition as their guiding principle. The eight floors will be reconfigured to house classrooms and administrative offices, and will be accessible from a welcoming, light-filled lobby on the ground floor. A series of tiered steps will lead to the first basement level, where students can enjoy a cafeteria that opens onto a terrace and landscaped area. This level will also feature a dedicated bike storage space. The second basement level will be reserved primarily for technical equipment rooms.

The designers took advantage of this transformation to bring the building up to standard and improve its functionality in terms of safety, acoustics, thermal insulation and accessibility. The renovation is forward-thinking, emphasising durability and reversibility. Should future needs change, the building will retain the ability to revert seamlessly to office space.

Reuse, low-carbon materials and low-tech innovation

This renovation embraces a philosophy of technical and environmental frugality. Committed to energy efficiency, the building has been designed to meet the targets of the 2040 Tertiary Decree. The project also aims for prestigious labels and certifications such as BREEAM Excellent, WiredScore, BiodiverCity, and the BBCA low-carbon label.

Key strategies to reduce the environmental footprint of this renovation project include:

• On-site waste sorting and waste reduction at source
• Reuse of reclaimed materials
• Use of biosourced materials.

The designers and their partners* came up with several solutions to make the building more energy efficient. A major effort has been made to improve the building envelope, where the challenge was to design a building cooled without air-conditioning. The building will rely on double solar protection on its rear façade, using both interior blinds and exterior shutters to minimise heat build-up during hot weather.

At the same time, preference will be given to the use of biosourced materials: flooring made of natural rubber, sound-absorbing wood wool ceiling tiles, and partitions made of compressed earth bricks sourced from local construction site excavations in the Ile-de-France region. These materials are key to high quality thermal and acoustic comfort and low water consumption.

Cascading green landscape thanks to 400 m² of terraces and gardens

The transformation also includes the creation of green spaces, a highlight of the project. Excavating part of the ground floor and basement will introduce a verdant garden with trees planted directly in the soil, available to students, teaching and administrative staff alike.
Connecting the garden to the green terraces is a staircase covered with climbing plants. This green journey culminates in a rooftop garden on the main building’s roof, providing a natural space for relaxation and rejuvenation.

This vertical network of greenery – from rooftop to basement – forms a canopy like a waterfall of foliage, enhancing the building’s thermal insulation and helping to combat the urban heat island effect on a local scale.

Boosting biodiversity

Creating green spaces and integrating spaces dedicated to biodiversity are central to this renovation. For students, these rewilded areas will offer a unique biophilic experience, in a learning environment designed for growth and well-being.

The site at 85 Rue du Dessous des Berges will feature 128 local plant and tree species, chosen for their resilience and durability. The selected species are adapted to the Parisian climate, making them easy to maintain and water. The wide variety will promote the development of biodiversity. These places will offer a range of micro-habitats such as nesting boxes, piles of dead wood and riprap for local fauna (insects, birds, etc.).

Creating these rewilded spaces also involves rethinking rainwater management, moving away from traditional drainage into the urban sewer system. Instead, rainwater will be captured naturally and used to nourish the vegetation and support the biodiversity.

*Delpha Conseil, VP&Green, Innovation Fluides, Impact Acoustic, Green affair, CAM Ingénierie, Be Terre, Batiss, AE75
*Biophilia: the biophilic approach aims to encourage the reconnection between humans and nature. In real estate, this means integrating greening approaches into building design to improve the health and well-being of users.

The circular economy, in its broader meaning, encompasses everything from materials management to the reuse of infrastructure, while also promoting shared use and short supply chains. These practices help to reduce waste, optimise resource use and foster more responsible consumption. By reusing existing structures and by sharing spaces, we contribute to sustainability and maximise benefits – whether environmental, social or economic.

If we look at materials, the construction sector in France generates around 46 million tonnes of waste, half of which comes from demolition sites*. Limiting this waste and transforming it into resources through reuse and the circular economy is one solution for creating resilient, low-carbon cities.

This approach, which leverages waste and recognises the value of reusing materials, encourages the use of existing resources and reduces the consumption of raw materials. This new mindset turns buildings into stores of materials and reservoirs of resources. Reusing what already exists instead of buying new is a philosophy with a tangible impact. For an area of 1,000 m², reusing materials can save:

• 44 tonnes of waste
• 67 tonnes of CO2 equivalent emissions
• more than a million litres of water.**

The circular economy, or how to recover real estate waste

In response to the environmental impact of construction, an increasing number of property developers are turning to the circular economy. In this approach, waste becomes a product for (re)consumption. At the end of its first life, waste is recycled to be incorporated into a building where it finds a new purpose, extending its lifespan and adding value to its original production.

In Neuilly-sur-Seine, along the corridor that links Paris to the La Défense business district, the office building at 185 Avenue Charles de Gaulle has undergone an ambitious renovation. BNP Paribas REIM, in line with its ESG strategy, envisioned a large-scale renovation for this property, owned by its Accès Valeur Pierre SCPI investment vehicle, conducted through an exemplary worksite.

Circular economy principles were applied during the demolition, allowing various materials from the former building to be reused in other renovation projects:

• 17,000 m² of carpeting for the World Trade Center project in Belgium
• 95 tonnes of metalwork for the Industrial Museum in Rouen
• 500 doors
• a generator unit
• sanitary fixtures (sinks, taps) and furnishings.

A careful methodology enabled the recovery and reuse of 97% of the demolition waste.

For the renovation work, the target of zero ultimate waste was achieved through measures such as setting up an on-site waste management facility, prefabricating sanitary blocks, using reclaimed materials and recycled paints, and incorporating low-carbon concrete. These efforts led to a 33% reduction in CO2 emissions compared to a conventional renovation project.

Environmentally-friendly real estate concept

Incorporating reused materials requires a dedicated logistics process. Careful dismantling and proper packaging are essential to maintain the quality of the product. When kept in good condition, these materials eliminate the need for new products, which would otherwise involve resource extraction, the consumption of energy for production and carbon dioxide emissions from transportation.

One of the auditoria at METAL 57 in Boulogne-Billancourt was designed in line with principles of the circular economy. To achieve this, BNP Paribas Real Estate partnered with Kataba, a social enterprise specialising in ethical furniture manufacturing. The eco-design of this space emphasised the reuse of materials and the selection of refurbished equipment, in particular audiovisual systems. Nine people on a work integration scheme contributed to the project, promoting a sustainable approach to interior design.

This initiative successfully reused 874 kg of materials and saved 6.8 tonnes of CO2 equivalent emissions, reducing the carbon footprint by five times compared to a conventional project of the same scale.

Transforming waste into resources

Reuse is a powerful tool for sustainable real estate. Ideally, modern construction projects should be designed with future demolition in mind in order to maximise the reuse of materials. While waiting for such forward-thinking construction practices to become the norm, other innovative methods are being trialled, such as construction using recycled materials.

One notable example is the Senckenberg Tower in Frankfurt, renovated by BNP Paribas Real Estate and featuring a façade made of 95% recycled aluminium. It is the tallest building in Germany to use this material. The figures reveal the progress and environmental benefits: producing 1 kg of primary aluminium in Europe emits an average of 8.6 kg of CO2, whereas 1 kg of recycled Hydro Circal*** aluminium emits only 2.3 kg – a 75% reduction in greenhouse gas emissions. The use of recycled aluminium has helped reduce the building’s carbon footprint by over 2,600 tonnes of CO2.

It is a challenge to standardise reuse practices because each real estate project has unique characteristics. The condition of the building and a detailed, case-by-case assessment are essential for identifying resources and opportunities. In Paris, the office building at 47 Quai d’Austerlitz, owned by the SCPI Accimmo Pierre, managed by BNP Paribas REIM, is undergoing a renovation with a strong emphasis on reuse to minimise the environmental impact. This 20-year-old building has been well maintained by its long-standing tenant, making a “careful dismantling” process possible, which has facilitated the recovery via reuse of nearly 400 tonnes of materials (such as cable trays, carpeting and raised flooring), equivalent to nearly 900 tonnes of CO2 equivalent. This represents roughly 15% of the project’s waste.

The project also plans to retain the exterior window frames, which are still efficient, preserving 15 to 20% of the existing frames. Additionally, all raised flooring panels that are in a good condition will be refurbished and reused on-site. Some still-functioning technical systems (backup generators, emergency chillers, transformers) will also be kept. This project is part of an ambitious environmental programme aiming for multiple certifications and labels, ensuring the building surpasses the 2040 Tertiary Decree standards by 2026 and achieves the new mixed-use BBCA (Low-Carbon Building) benchmark.

Industrialising reuse and the circular economy in real estate requires the engagement of all professionals across the value chain.

Collaborative efforts are essential to jointly define how potential resources from building renovations are recycled and to establish appropriate supply chains. BNP Paribas Real Estate is a partner of CircoLab, a circular economy think tank that advocates for renovation, repair and reuse in order to:

• extend the lifespan of materials and reduce the consumption of raw materials at source
• encourage the recycling of waste to supply raw material resources.

BNP Paribas Real Estate is also part of the Booster du Réemploi initiative, which aims to reduce the carbon footprint of the construction sector by 20 to 30% through the reuse of materials. Its platform connects suppliers and users interested in reused materials.

The circular economy and reuse are challenging the economic models promoted in recent decades. While initial costs for these practices may be higher, they can prove profitable over the long term. Nonetheless, there remain many challenges to be tackled, including regulatory, construction and insurance-related obstacles. Inspiring urban stakeholders to adopt these environmental approaches is vital. Raising awareness will encourage the entire real estate sector to promote the approach and integrate principles of the circular economy into its projects. Only through collective participation and investment can developers, architects and companies work together to build sustainable cities.

* Building resources and waste: The circular economy to improve waste management practices. - Observatory for Sustainable Real Estate (o-immobilierdurable.fr) [in French]
** Booster – Reuse in the construction sector (boosterdureemploi.immo) [in French]
*** https://www.hydro.com/fr/