The purpose of this project was to design a site to gather GRDF's tertiary activities in the South-East region, i.e. to bring together 375 employees, previously spread over 5 sites. For its realisation, the conservation of the heritage value of this former Ford garage from the 1950s, an emblematic place on Avenue Berthelot, had to be combined with the need to adapt the site to the company's activities by adding a new high-performance, green office building. In addition, this project reflects the desire to build the city on the city and reduce heat islands. 

The emphasis is on climate engineering with the collaboration of Clévia (Eiffage Energie Systèmes) and Adexsi. The building is designed using innovative and efficient energy systems that reduce energy consumption while ensuring summer comfort for occupants, earning it the Effinergie+ building label. 

 

Efficient energy systems

Adiabatic cooling

The reduction of energy consumption due to the regulation of the temperature of the premises is first and foremost integrated into the design of the building. Its high inertia protects against heat peaks by storing heat and releasing it by diffusion, thus delaying the rise in temperature.

In addition, climate engineering is used to optimise the use of energy for heating and cooling the building. At night, an over-ventilation system provided by a double flow air handling unit (AHU) with energy recovery uses the night-time coolness to evacuate the heat accumulated during the day. For the hottest days, an active air conditioning system consisting of refrigeration units located on the roof complements the AHU. 

Finally, the emphasis is on technological innovation with an adiabatic module attached to the AHU, which recycles hot air and minimises the need to use active air conditioning during prolonged periods of intense heat. This solution is both environmentally and economically sound and ensures the low carbon impact of the building. 

Thus, particular attention is paid to the summer comfort of the occupants and to well-being at work, while minimising the environmental impact. The distribution of cold and heat was entrusted to a 4-pipe system controlled by an "intelligent" supervision system, which allows the distribution of heat and cold in the premises, while supplying the fan coil units and the water coils of the AHU.

Diagram of adiabatic installation GRDF project

Natural gas heating

In the technical room on the roof, two 136 kW natural gas condensing boilers ensure a suitable indoor temperature, even when outside temperatures are low. This system also ramps up quickly to avoid unnecessary energy consumption when the building is unoccupied. 

Thanks to these systems, the building complies with RT2012 with a Bbio -20% and Cep -40%.

 

Conservation of the site's heritage 

This project aims to preserve the industrial structure of the building, while adapting the aesthetics of the envelope to modern standards. Indeed, the historic facade of the site has been preserved, despite constraints such as the absence of windows, the particularly thick walls and the 2.20m high floors instead of the recommended 3.50m. The contemporary choice of solid cut stone as a material was a real challenge due to economic, technical and seismic constraints. Negotiations were undertaken with the Architectes des Bâtiments de France (ABF), the City of Lyon and the Metropolis to successfully complete this heritage enhancement. 

The former Ford garage

 

A participatory design process

Working groups were organised between employees and architects to enable the former to share their conception of suitable work spaces. This was done in particular with regard to the layout of offices, open spaces, work bubbles and furniture. Taking into account the changes in teleworking implemented since the beginning of the Covid-19 pandemic, the workstations are not nominative, which makes it possible to optimise the use of the space. From the outset, the building has been designed to respond to current lifestyles and potential future changes in use. This increases its reversibility and therefore its lifespan. 

In addition to the canteen, a concierge service and a private planted area, the complex includes the "village square", a pleasant space where employees can meet, with the aim of stimulating the exchange of ideas, collaboration and the birth of innovations.