The Cité Descartes demonstration building

How can we promote renewable energies and shared resources in local neighbourhoods to reduce the environmental footprint of buildings?

The Cité Descartes demonstration building offers an answer. Eric Blanc, technical director of the setec building engineering physics department, shows how new solutions can optimize energy consumption in existing installations.

Developed by Vinci Construction France, the Cité Descartes demonstration project is a 25,000 m2  complex on a 11,211 m2   site in Champs-sur-Marne in the Parisian suburbs.

The project aims at developing  innovative low-energy technologies that could be implemented in France and abroad, with the support of Efficacity (a private R&D institute focusing on energy transition).

setec, the prime technical contractor, has proposed a concept to optimize energy strategy for the entire neighbourhood. This solution starts with an existing commercial building (comprising education, research and business activities) that uses groundwater as a captive energy source. However, since it generally requires more cooling than heating, the building expels proportionally more heat, which needs to be cooled with air (dry coolers).

The idea put forward by setec’s teams is to recover the heat released by this building to provide energy for the future complex of multipurpose buildings, including homes, which tend to consume more heat than cold. An energy storage system compensates for the irregular supply of energy from this resource so that the building can be heated all year round.

A memorandum of understanding for power exchange has just been signed between Dalkia and the owner of the existing building. Dalkia will own this new energy network.

This is an effective solution for both buildings. In particular, it will halve the work of the dry coolers in the existing building.

The option of connecting other buildings to the network will be examined in the future.

The long-term objective is for 75% of the neighbourhood’s heating needs to be covered by renewable and recoverable energy, dividing CO2 emissions by five. In particular, high-temperature geothermal energy will replace traditional gas boilers.

This system, which reuses geothermal energy captured for one building to power a new real estate project, is currently unique in France.

At the same time, setec has carried out an energy efficiency study for the new building complex, depending on the programming. This resulted in an update in plans (4,000 m of housing replacing offices) – another success, considering architecture and energy efficiency together from the outset of the project.

Planning permission was filed in November 2016 for a construction start date in September-October 2017 and completion in 2019.