Supporting the energy optimisation of future stations on the Grand Paris Express network

What innovative solutions for optimising the energy efficiency of a station?


SGP called on Efficacity to accelerate deployment of new technology on lines 15 and 18 of the Grand Paris Express network. These technologies will make the project a showcase for French excellence in the field of sustainable transport, deployed on behalf of the residents of the capital.


The partnership’s main mission is to identify areas where the energy efficiency of future stations can be optimised thanks to:

  • Study of the geothermal potential of all the stations, followed – for those with considerable potential – by a more detailed analysis with a view to incorporating geothermal energy in diaphragm walls;
  • Study of the pertinent criteria for characterising the energy efficiency (heating and cooling) of a station;
  • Study of innovative legal solutions to encourage the resale of heat to third parties;
  • Study of instrumentation solutions to ensure continuous monitoring of station performance and optimised control of infrastructure.


Efficacity called on the skills of its network of public and private sector members to complete the following phases:

  • Analysis of data supplied by the SGP project managers (station plans, projected infrastructure, technologies, etc.) and reference data (choice of rolling stock, setpoint temperature of premises, etc.);
  • Energy appraisal providing SGP with a second opinion;
  • Identification of avenues for optimisation including geothermal, infrastructure management, heat recovery;
  • Legal analysis of the resale of heat to third parties.


The support provided and studies conducted by Efficacity resulted in SGP gaining the authorisation to resell energy to third parties (by means of an amendment to the law on the Métropole du Grand Paris passed in February 2017), and also to win approval from the SGP Investment Committee for the inclusion of geothermal energy at four stations on the network (Line 15South). To date, two stations are under construction, featuring diaphragm walls fitted with geothermal membranes. Studies are continuing into the economic and legal models for recovering this energy.

Client Société du Grand Paris (SGP)

Dates 2014 – 2018

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Ces technologies permettront de faire du projet une vitrine de l’excellence française en matière de transport durable