Cité Descartes: a demonstration block contributes to the energy strategy of the neighbourhood

In Champs-sur-Marne, the demonstration project promoted by Vinci Construction France proposes a 25,000 m2 development on a block in the centre of the new town. The consideration of the energy consumptions has been broadened to a more comprehensive approach on the scale of the neighbourhood.

The demonstration building project aims to develop innovating technologies, including with regard to energy consumption, applicable both in France and abroad, with support from Efficacity (R&D institute for urban energy transition, comprising private-sector entities in association with the university world).

setec bâtiment, technical designer of the project, proposed an energy consumption optimisation system linked with an existing building. The building, which draws its energy from an aquifer, uses more cooling than heating overall. It consequently discharges more heat that has to be cooled by exchange with the air (air coolers), as the aquifer is confined. The idea put forward is to use the heat discharged by the existing building to supply energy to the future block of buildings, which is multi-functional, includes housing, and consequently uses more heating than cooling. An energy storage system smooths the intermittency of this resource, so the building can be heated all year round.

An effective solution for both buildings

The system halves the operating time of the air coolers of the existing building.

The long-term target? 75% of heat needs supplied by renewable and recoverable energies, together with a five-fold reduction of the CO2 emissions for the neighbourhood, achieved in part by the replacement of a gas-fired boiler with high-temperature geothermal energy from the Dogger formation. At present this is the only such system in France.

Setec also conducted a study of the energy efficiency of the block, which led to an adjustment of the programme (4000 m2 of housing replacing 4000 m² of offices). Another fruitful approach, combining work on the architectural form with optimisation of energy efficiency from the beginning of the project.