Ministry of Defence, Paris, France


The French Ministry of Defence decided to regroup its services into a single building, located in Paris’ 15th district. The project was launched as a Public Private Partnership tender that was awarded to the Bouygues/Agence Nicolas Michelin et Associés team.

The building consists of 120,000m² of office space, designed not only to reach HQE environmental targets, but also to obtain the BBC energy label and respect Paris’ strategic ‘Plan Climat’.

The architect, Nicolas Michelin, wanted the building image to underline a strong environmental message. He therefore integrated natural extraction chimneys into the architectural concept, which work by combining ventilation thermal effects, resulting in a complex, optimised hybrid ventilation system.

Deerns performed complex CFD analysis of the natural extraction chimneys to determine their potential and to predict different functionalities of the hybrid ventilation solution. The commission included the sizing and design of the chimneys and their interface with the air-handling units.

Beforehand, we carried out a detailed comparative analysis of several variations, in particular of the resulting pressure drops at the head of the chimneys and along the façades. The process was an iterative one in close collaboration with the architect and engineers. It resulted in an optimised natural extraction mixed-mode solution.