ENS Paris-Saclay in Gif-sur-Yvette, France, designed by Renzo Piano Building Workshop for École normale supérieure Paris-Saclay – completed in 2020
Project overview
Completed in 2020 in Gif-sur-Yvette, in the Moulon district of the Paris-Saclay campus, the new École normale supérieure Paris-Saclay campus was designed by Renzo Piano Building Workshop. The GBE System was used primarily to construct the large insulated concrete gable walls separating the principal campus blocks. These walls consist of two reinforced concrete leaves cast simultaneously in place around integrated rigid thermal insulation. The wall build-up was locally adapted to create vertical structural zones within the thickness of the wall, enabling concentrated floor loads to be transferred where required. Some walls were cast to heights approaching 7 m using Lafarge Ultra Twin GBE self-compacting concrete, without vibration. The concrete gable walls contribute to the mineral architectural expression of the campus, the continuity of the building envelope and its bioclimatic strategy, which combines insulation, concrete thermal mass and natural ventilation.
Key project data
Project:
New ENS Paris-Saclay campus
Location:
Gif-sur-Yvette, Essonne, Moulon district, France
Building programme:
Higher education, research, administration, dining facilities, library, auditorium and Scène de recherche
Client type:
Public-sector client
Client:
École normale supérieure Paris-Saclay
Architect:
Renzo Piano Building Workshop
Structural concrete contractor:
Campenon Bernard Construction – Vinci Construction Group
Construction system:
Cast-in-place double reinforced concrete wall with integrated thermal insulation – GBE System
Wall build-up:
Two reinforced concrete leaves with integrated rigid thermal insulation; locally adapted to create vertical structural reinforcement zones
Architectural finish:
Light-coloured exposed concrete with horizontal recesses incorporating construction joints into the architectural design
GBE scope:
Insulation support components, spacers, installation tools and technical assistance
Architectural design and construction using the GBE System
What architectural, structural and bioclimatic requirements did the gable walls need to address?
The campus brings together large teaching and research volumes, vertical circulation, shared facilities and different façade systems around an internal garden of more than one hectare. The concrete gable walls between the principal building blocks therefore had to meet architectural, thermal and structural requirements simultaneously. On the classroom and laboratory side, some of these walls locally support floor loads; on the opposite side, they border circulation areas and other spaces that remain within the building envelope. The GBE System integrates rigid thermal insulation between two reinforced concrete leaves cast in place while maintaining substantial concrete mass on the internal side. This thermal mass contributes to the campus’s bioclimatic strategy, which also incorporates natural ventilation, solar shading and the central garden. Integrated insulation helps reduce heating and cooling demand, while the exposed concrete provides the mineral architectural expression sought by Renzo Piano Building Workshop.
Why was the GBE System suited to this project?
The GBE System was suited to the ENS Paris-Saclay gable walls because it made it possible to combine integrated thermal insulation, structural function and exposed concrete within a bespoke wall assembly. The system is not prefabricated: the two reinforced concrete leaves are cast simultaneously in place on either side of the insulation using conventional formwork construction methods. This flexibility allowed the insulation thickness to be locally reduced so that the concrete section could be increased where required, creating concealed vertical structural reinforcement zones within the wall. The concrete surface therefore remains continuous without the repeated joints associated with prefabricated panel construction. Construction joints were incorporated into the architectural design through horizontal recesses. On site, some walls reached heights of nearly 7 m; concrete placing channels were used to limit the free-fall height of the self-compacting concrete and facilitate consistent filling of both concrete leaves without vibration.
What benefits does this project demonstrate?
ENS Paris-Saclay demonstrates the ability of the GBE System to combine structure, thermal insulation, thermal mass and architectural expression within a single wall assembly. Continuity of the insulation through the standard wall areas contributes to reducing long-term heating and cooling demand, while the mass of the internal concrete leaf contributes to summer comfort and helps moderate indoor temperature variations during periods of high heat. The insulation is protected between two concrete leaves, supporting the durability of the building envelope and a low-maintenance approach that is particularly relevant for a public-sector client managing its buildings over the long term. The project also demonstrates the flexibility of cast-in-place construction: local structural adaptation, continuous gable walls, large casting heights and the architectural integration of construction joints. The overall campus project received the BIM d’Or in 2015 and the Grand Prix at the 2017 Fimbacte Festival in the project category.
Project awards and recognition
- BIM d’Or 2015: Winner
- Fimbacte Festival 2017: Grand Prix, project category
These awards and distinctions relate to the architectural project and campus as a whole, rather than specifically to the GBE System.
