UNESCO

Renovation of an occupied heritage office building

Located in the 15th arrondissement of Paris, near the UNESCO headquarters on Place de Fontenoy, Building V — designed by Bernard Zehrfuss and Jean Prouvé and inaugurated in 1970 — offers an exceptional opportunity due to its well-preserved original condition.

Commissioned for this heritage renovation project, Patriarche’s teams are working on its preservation and reinterpretation with a focus on energy efficiency. The renovation is being carried out while the site remains occupied, in a complex urban environment.

The program includes:
• Upgrading safety and accessibility standards, and replacing all technical installations to meet comfort, energy efficiency, and low-carbon building criteria;
• Restoring the original façade, reusing materials, and enhancing the building’s heritage value;
• Requalifying interior spaces such as the lobby, offices, and restrooms, and enhancing outdoor areas including the patio and Miollis garden.

Ultimately, the renovated building will meet the objectives of Paris’s Territorial Climate and Energy Plan, with the HPE BBC-Effinergie Renovation 2009 label, aiming to reduce the building’s energy consumption.

Client : UNESCO

Location : Paris, France

Size : 16 711 m²

Status : Delivered

Date : 2023

Key points

  • Facade Renovation
  • Consideration of existing heritage.
  • Preservation of geometries and atypical structures.
  • Thermal, humidity, and acoustic comfort.
  • Implementation of accessibility for persons with reduced mobility (PRM).
  • Creation of gardens.

Environmental perfomances

  • Target: BBC Effinergie Renovation label.
  • Ubat -63%, 70% reduction in energy consumption.
  • Reuse of materials (between 7% and 15%).
Download the project sheet

An updated and reinforced façade concept

Avant et après des panneaux de façade Unesco à Paris

Insulation

With a building dating back to the 1960s, well before the first thermal regulations were introduced, several technical challenges have been identified: the complete absence of insulation on vertical walls, no thermal bridge breakers, and the presence of single-glazed windows significantly reduce the building’s thermal performance, making it highly energy-consuming.
To improve energy efficiency, it is necessary to implement an effective insulation system integrated into the façade modules, along with the installation of thermal bridge breakers in the joinery.

 

Waterproofing

The waterproofing of the existing building was also in poor condition. The flat roofs showed waterproofing issues at weak points such as upstands and junctions between the lateral wings and the superstructure. In some areas, design flaws or drainage issues led to water stagnation, further impacting the building’s thermal performance.

 

The updating of these technical processes is carried out with the aim of remaining faithful to the original work, while offering an improved and modernized version of its performance.

Photos de l'intérieur du bâtiment de l'UNESCO à Paris
Façades de l'UNESCO

A lasting and efficient historic construction

Originally designed with a bioclimatic approach in mind, our mission is to improve the building’s performance while preserving its initial intentions. As energy performance standards have evolved since the building’s construction, it was necessary to conduct an updated analysis and diagnosis to accurately exploit and optimize its structural elements.


Control of comfort and energy consumption

With a dual objective, the rehabilitation of this office building aims to be updated to meet new standards and energy efficiency needs, revealing a sustainable and responsible architecture while offering greater comfort to its users.
The following key steps define the process to achieve these ambitions:

  • Rethinking the façades
  • Day-night thermal lag
  • Thermal insulation
  • Solar gain management
  • Bio-sourced materials
  • Roof renovation
  • Renewable energy
  • Ventilation optimization

The renovation of this heritage work aims to make the building less energy-intensive while improving user comfort.

Façades de la réhabilitation de l'UNESCO

Team

Patriarche (Architecture, Engineering, Environmental, Cost assessment)
Partners : Ragot Gilles, Eckersley, O’Callaghan, MDP, Omega Alliance, Lamoureux, Casso & Associés

Crédits

Photos : ©Nicolas Grosmond

Program

Historic Monument
Offices
Rehabilitation
salles de reunion gearbox Gearbox Montreal Craft logements et bureaux Craft