Last modified by the author on 25/04/2018 - 16:56

Extension + refurbishment

  • Building Type : High office tower > 28m
  • Construction Year : 1975
  • Delivery year : 2015
  • Address 1 - street : 204 Rond point du Pont de Sèvres 92100 BOULOGNE BILLANCOURT, France
  • Climate zone : [Cfc] Marine Cool Winter & summer- Mild with no dry season.

  • Net Floor Area : 85 429 m2
  • Construction/refurbishment cost : 200 000 000 €
  • Number of Work station : 5 200 Work station
  • Cost/m2 : 2341.13 €/m2

Proposed by :

  • Primary energy need
    99.63 kWhep/
    (Calculation method : RT existant )
Energy consumption
Economical buildingBuilding
< 50A
51 à 90B
91 à 150C
151 à 230D
231 à 330E
331 à 450F
> 450G
Energy-intensive building

Formerly "Building of Pont-de-Sevres" erected during the 1970s from the hexagonal plans of architects Daniel Badani and Pierre Roux-Dorlut; Citylights was renovated between 2007 and 2015. Renovation plans were designed by architect Dominique Perrault. The smooth facades have been replaced by faceted modules that reflect the light and the city hence the name of the project, Citylights. The 75,000 m² of towers have been rehabilitated, while 10,000 m² of extension have been erected. Promoted by the promoter BNP Parisbas Real, supported by General Electric, Citlylights is involved in the revitalization, beautification and dynamism of the Pont de Sèvres district and is a remarkable architectural sign.

High rise building (IGH) of 82000 m², Citylights is composed of three towers City1, City2, City3 united by a central and monumental Agora. The tower has benefited from an exemplary environmental strategy so that its use is virtuous from the point of view of the integration of the builyyyding into its environment, the materials used, the management of energy, the waste, the water and to guarantee an exceptional comfort to the tenants that are General Electric and Solocal.

Proof of its commitment and its exemplarity, the project combines the certifications: HQE construction and renovation certification was obtained in March 2016, HQE exploitation in January 2017 and Breeam certification excellent level in May 2017.

A particular asset of the CityLights project is the provision of a wide range of services: a 300-seat auditorium, a conference center, a fitness and relaxation area, a concierge service and five different dining areas.

Sustainable development approach of the project owner

The client has chosen to pay particular attention to the design of the structure, on the reduction of environmental and health impacts. It is in this context that the project sought a double environmental certification HQE Exceptional level and BREEAM level Excellent during the construction and renovation of the property complex. This approach only makes sense if it is extended by a similar approach during the life phase of the book. An environmental certification HQE in Exploitation Level Excellent was thus obtained on the real estate complex in January 2017, committed by AFUL Citylights and by the owners SCI Citylight Boulogne and SCI Tour City 2 represented respectively by BNP Paribas Cardif and Gecina. An environmental lease schedule has been created. Flagship measure of the Grenelle Law, the environmental annex aims to engage landlords and tenants to "improve the energy and environmental performance of the building and leased premises" through the communication of information and the implementation of a program of actions . The green annex to the lease therefore allows contracting this commitment. For information, Decree No. 2011-2058 specifies the content of the environmental annex to be inserted in all current commercial leases covering lots> 2000 m² since 14/7/2013. Citylights' life including sustainable development approach and adaptable behaviors is available for all occupants of the tower. This notebook makes it possible to take knowledge of the assets of the site. The owner of the building communicates through this guide on the efforts undertaken and the willingness to offer user-oriented workspaces, his health and comfort.

Architectural description

The towers were adorned with a sparkling line visible from afar, which highlights their silhouette in the landscapes of the Seine loop. Oblique facade elements encase each tower on one third of its height; and a base connecting them extends over 3 levels. The surroundings of all (sides gardens and sides parvis) were reworked to offer a better reception to users and a better connection to the surrounding neighborhood.


- Five restaurants (4000 m²)

- Fitness center (500 m²)

- One day nursery (377 m²)

- Two shops (307 and 240 m²)

If you had to do it again?

"We wanted to take up the challenge of this project, because we felt the opportunity to boost the aesthetic and technical quality of this dilapidated set to make it a beacon of corporate real estate of the 21st century" - Bruno Pinard, Director General of BNP Paribas Immobilier Promotion Real Estate Business

See more details about this project


    SCI Citylights Boulogne et SCI Tour City 2

    SCI Citylights Boulogne et SCI Tour City 2 sont représentés respectivement par Paribas Cardif et Gecina.

Construction Manager



    BNP Paribas Immobilier Promotion Immobilier d’Entreprise

    Elvys Fiokouna

    Environmental consultancy

    Other consultancy agency


    BET structure & fluids - Mastery of work

    Other consultancy agency


    BET Façade - Mastery of work



    Curettage, asbestos removal

Type of market

Global performance contract

Energy consumption

  • 99,63 kWhep/
  • 183,06 kWhep/
  • RT existant

  • 181,48 kWhep/

Envelope performance

    All the old façades with concrete spandrels and windows were replaced during the renovation of Citylights by high-performance curtain walls insulated with plates of rock or glass wool insulation depending on their location.
    The joinery of aluminum profiles is thermal break, which avoids having a significant temperature difference between the glazing and the frame. This allows for a uniform wall temperature and reduces heat loss through the facade. In addition, the insulation of the other opaque walls was reinforced: roofs and low floors were insulated with the appropriate materials. These building envelope improvements improved the thermal performance of the walls by 60% compared to the pre-retrofit condition.

More information

Calculation method RT 2005 for extension and existing RT for renovation


    • Urban network
    • Heat pump
    • Others
    • Individual electric boiler
    • Urban network
    • Water chiller
    • Roof-top
    • Urban network
    • Chilled Beam
    • Double flow heat exchanger
    • No renewable energy systems

Smart Building

    A centralized technical management (GTC) optimizes and accounts for the consumption, in particular the venetian and automatic blinds of the double skin.

Urban environment

    Initially, the towers were disconnected from their environment. Today, pedestrian paths make it possible to cross towers and the Trapèze district, where office buildings and housing have been built on the wasteland of former Renault factories. Spaces have also been designed to "open the project to the outside: including footpaths, gardens and a large square in front of the towers. For Dominique Perrault, the architect of the project, "the devices for welcoming, walking and living together seek to create new workspaces in harmony with our world". Citylights towers are served by many public transport: metro at the foot of buildings, and soon the network of Grand Paris whose all stations will be connected to the towers.


    Facade in ventilated panel blocks



    Gros œuvre / Structure, maçonnerie, façade

    Facades in thick ventilated block-panels, with integrated venetian blinds

Indoor Air quality

    The materials were chosen according to their health impact so that it is as limited as possible. This point is guaranteed for the labels required (eg Ecolabel) for the installed materials.


    Attention was paid to the limitation of noise (choice of appropriate equipment) and lighting (choice of luminaires, orientation of luminous flux, ...) on the plot, as well as the limitation of discharges. All the roofs have a vegetalization, gardens on slabs were created at the level of the central terraces. Logbook given to all the occupants of the building

    Des études thermiques en conception ont été réalisées afin de limiter au maximum les périodes d’inconfort thermique possible dans les locaux sur l’année et sur le temps d’occupation.

    The facade and joinery implemented constitute a good sound barrier with the outside. An acoustic study was conducted in 2016 to identify external and internal sources of noise for acoustic measurements. This study confirmed the achievement of the minimum thresholds to achieve HQE construction certification.

Building candidate in the category

Energie & Climats Tempérés

Energie & Climats Tempérés

Coup de Cœur des Internautes

Coup de Cœur des Internautes

Prix des Etudiants

Prix des Etudiants

Green Solutions Awards 2018 - Bâtiments

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Green Solutions Awards 2018 - Bâtiments