Rehabilitation of the Hôtel des Postes - Strasbourg

The project consists of the massive rehabilitation of the Hôtel des Postes in Strasbourg to significantly reduce the building's carbon footprint.

Main project's drivers for reducing the greenhouse gas (GHG) emissions

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Energy and resource efficiency

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Energy Decarbonisation

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Energy efficiency improvements

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Improving efficiency in non-energy resources

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Emission removal

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Financing low-carbon issuers or disinvestment from carbon assets

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Reduction of other greenhouse gases emission

Project objectives

Reducing the carbon footprint of the construction of a former post office building during a massive rehabilitation operation.

Detailed project description

Reducing the carbon footprint of its activities is an essential requirement in the conduct of Bouygues’ operations.


This major renovation project concerns a former post office building of neo-Gothic architecture, located in a district classified as a UNESCO heritage site. It is spread over a surface area of 20,000 m² that has been entirely renovated, with 2,000 m² dedicated to the new building. The aim here is to reduce the carbon impact of the operation and to save resources and raw materials while preserving the existing structures as much as possible, and using the circular economy.


The future use of the building is distributed as follows:

  • 62 units in open access (Premium)
  • 20 units in dismemberment
  • 18 subsidized rental units
  • 1 managed residence of 84 units for seniors (Jardin d’Arcadie)
  • 2,400 m² of offices
  • 1 Brewery
  • 1 post office


The historic building is located at the edge of the plot and occupies a large part of the land. This building will be entirely renovated to accommodate all the real estate products defined above.

A basement for the parking of motorized vehicles will be built. The inner courtyard of the building will also house a new office building, the “Cluster”.


The project has been awarded the following labels: “Effinergie” renovated housing and “BREEAM” new commercial buildings.

The operation is also a winner of the BTP 2020 call for projects entitled “Mobilizing the entire construction industry to meet the challenges of waste reduction and recovery” of the CLIMAXION program initiated by ADEME and the Région Grand Est.


Principle of the circular economy implemented

The whole structure, the facades and the roof have been preserved. In addition, a part of the wooden windows was kept either by reusing them in situ or by valorizing them ex situ. The conservation and renovation of a large part of the interior doors was also possible. As for the carpet, it was removed and used for insulation.


This rehabilitation operation also allowed a saving of 57 million liters of drinking water compared to a new operation of the same surface.

Emission scope(s)

on which the project has a significant impact

Scope 1

Direct emissions generated by the company's activity.

Scope 2

Indirect emissions associated with the company's electricity and heat consumption.

Scope 3

Emissions induced (upstream or downstream) by the company's activities, products and/or services in its value chain.

Emission Removal

Carbon sinks creation, (BECCS, CCU/S, …)

Avoided Emissions

Emissions avoided by the activities, products and/or services in charge of the project, or by the financing of emission reduction projects.

Scope 3 – Circular economy and reuse of materials with conservation of an existing building.

  • Avoided emissions (compared to new materials) :

    – for the carpet: 1,239kg CO2eq;

    – for windows: 2,087kg eq CO2 :

    • pour la moquette : 1 239kg eq CO2 ;
    • pour les fenêtres : 2 087kg eq CO2

Scope 3 – Connexion au réseau de chaleur urbain

  • Quantification : gain au global de 426kg eq de CO2 par m2, par rapport à un projet standard neuf en France (sur l’empreinte carbone globale du bâtiment).

Scope 3 – Usage de béton à émissions de CO2 réduites

  • Quantification : 92 tCO2 (par rapport à un béton classique)

Analyse globale, produit de construction et équipement (PCE) et Energie.

Cette analyse porte sur le poids carbone global du bâtiment, à savoir le périmètre PCE + Energie en exploitation.

Grâce notamment au réseau de chaleur vertueux de l’Esplanade (70% d’énergie renouvelable), les logements du programme Hôtel Des Postes émettent au global 30% de CO2 en moins qu’un logement standard chauffé au gaz.

Données utilisées :

  • Facteur d’émissions du béton utilisé (en le comparant à celui d’un béton standard) : le béton utilisé sur l’opération est du CEM III qui est à 160 kgéq.CO²/m3, comparé à un CEM II « classique » qui est à 240 kgéq.CO²/m3 ;
  • Facteur d’émission du réseau de chaleur utilisé (en le comparant à celui de la source d’énergie qui aurait été utilisé à la place) : 344 kgéq.CO²/m² sdp pour l’opération de l’Hôtel des Postes, comparé aux autres opérations de Bouygues Immobilier qui sont à 673 kgeq.CO²/m² sdp en moyenne ;
  • Quantités de moquette recyclée installée et le nombre de fenêtres et les facteurs d’émissions considérés (avec leur source) :
    • Moquette : 2 700 m² de moquette ont été recyclés auprès d’une autre société pour en faire de l’isolant. Le facteur d’émission fin de vie de la moquette est de 0,459 kgéq.CO²/m², donc cela donne 1 239 kgeq.Co² évité ;
    • Fenêtres : 59 menuiseries, donc 216 m² ont été déposés et réemployés ex-situ. Le facteur d’émission fin de vie de la menuiserie est de 9,66 kgéq.CO²/m², donc cela donne 2 087 kgeq.Co² évité.

Key points

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Invested amount

34 M€HT

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Starting date of the project


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Project localisation

Strasbourg, France

Project maturity level

Prototype laboratory test (TRL 7)

Real life testing (TRL 7-8)

Pre-commercial prototype (TRL 9)

Small-scale implementation

Medium to large scale implementation

Economic profitability of the project (ROI)

Short term (0-3 years)

Middle term (4-10 years)

Long term (> 10 years)

Illustrations of the project

This project contributes to the following SDGs:

  • SDG 12 Sustainable consumption and production: the principles of the circular economy have been followed for the use of certain materials on the site, thus reducing the consumption of new raw materials while recycling certain components.

This goes in the direction of a more responsible and above all sustainable consumption and production. This is a moderate and efficient use of resources perceived as non-renewable, while optimizing the life span of consumer goods and ensuring that nothing is lost.

  • SDG 13 Climate change: the rehabilitation of the building and the circular economy implemented on this project avoids new CO2 emissions while recycling some materials. Thus, less carbon was emitted throughout the production chain, whether for the extraction of raw materials or for the transport of the latter.

The following 2 points will have been avoided:

  • Total demolition of the existing and carbon emissions

New construction, consumption of non-recycled raw materials and carbon emissions.

Project entirely reproducible under the same conditions (same type of initial building).

Owner: Bouygues Immobilier

Architect – Agence Weber & Keiling

Assistant Project Manager: Environment – ELAN

Cleaning company – Lingenheld

General contractor – Bouygues Bâtiment Nord-Est

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