Stimergy’s IT servers will heat the indoor swimming pool at la Butte-aux-Cailles in Paris

Press Release – The French start-up Stimergy has been selected by the Paris City Hall to heat the indoor swimming pool at la Butte-aux-Cailles, thanks to its data center, which is more environmentally responsible than Google’s.

Stimergy, the start-up and French market leader in the recovery of heat through digital technology, will equip the swimming pool at la Butte-aux-Cailles in Paris with several ‘digital boilers’ in autumn 2016. Stimergy was founded in 2013, is supported by both EIT Digital and KIC InnoEnergy, and is currently incubated in the Grenoble-based premises of KIC InnoEnergy France.


Environmentally-friendly hot water for swimmers in Paris

Stimergy’s digital boiler recovers the waste heat from the servers which are installed in the swimming pool infrastructure, and recycles it to supplement the hot water requirements of the indoor pool. Since the servers operate continuously, digital heat is produced by Stimergy without interruption.

The city of the future is taking shape now: Paris sets an example

The swimming pool at la Butte-aux-Cailles is a world first. It demonstrates the relevance of installing digital boilers directly within those facilities which consume hot water. With this first project, the City of Paris shows by example that local authorities can now contribute in an economic and ecological way to increasing the energy performance of buildings and to data hosting in France.

Green IT made in France

The digital boiler at the swimming pool at la Butte-aux-Cailles is part of Stimergy’s innovative data center system, which is available throughout France and can host the data and applications of large organisations. If the indoor pool requires maintenance, the energy supplied by the data center is allocated to a second pool, in order to avoid any loss of the energy produced. Even in an extreme situation, if a pool should collapse, the servers will remain protected from the water and operational. Combined with other data centers, Stimergy’s system thus ensures high availability at a competitive price and with a reduced environmental impact. A dedicated entrance, as well as three-stage card-based access and a video surveillance system have been set up to control access to the digital boiler.

Energy performance superior to Google’s servers

The energy performance of Stimergy’s servers is highly competitive, with a PUE (Power Usage Effectiveness) ratio which tends to be below 1.10. Google, the world leader in the market, offers ‘Google Green’ servers with a PUE of 1.14, and does not recover their waste heat!

– Quotes –

photo_christophe_perron_stimergyChristophe Perron, Founder and CEO, Stimergy: “Swimming pools represent one of the highest energy costs for local authorities. Our data centers are a solution for the future for those areas which are committed to sustainable development, and offer energy performance which is superior to Google’s servers. They allow local authorities and businesses to host their services and data in a secure, economic and environmentally responsible manner.”


Jean-Louis Missika, Deputy Mayor of Paris responsible for city planning, architecture, Greater Paris area projects, economic development and the attractiveness of the city: “As part of the city’s Climate Policy, the swimming pools of Paris provide new settings for environmental innovation. The digital boiler at la Butte-aux-Cailles achieves our ambition of creating an intelligent and sustainable city. It helps improve the energy mix in Paris. The City intends to meet a dual objective: to increase the share of renewable and recovered energies to 25% of Paris’ energy consumption by 2020; and to be an attractive and innovative city, by encouraging the establishment of secure and powerful data centers there.”

Thomas Perineau, Civil Engineer, Heritage and Architecture Department, Engineering Section for Energy and Climate Control Systems – Paris City Hall: “We were won over by the solution presented to contribute to heating the swimming pool at la Butte-aux-Cailles. It is an ecological and efficient alternative energy. The process designed by the start-up recovers the waste heat from the pool’s servers, with an excellent PUE of 1.12. The hot water produced in this way reduces the total energy requirement for the correct operation of the swimming pool. In addition, the ease with which this solution can be connected and installed is a real advantage. It allows for the service to continue during maintenance work, so that the pool remains open to Parisians.”

La Butte-aux-Cailles / Stimergy in brief

  • Stimergy responded to the request for tender by the City of Paris in July 2015 which related to the supply of energy – produced onsite from the recovery of calories generated during IT operations – for the swimming pool at la Butte-aux-Cailles.
  • Stimergy’s bid covered the installation of a new system which would allow savings equivalent to 45 tonnes of CO2 each year.
  • Stimergy’s system will be operational in autumn 2016.
  • The swimming pool at la Butte-aux-Cailles comprises three pools, of which one (a pool of 33m in length) is indoors and will be heated in part by Stimergy’s digital system, and two (25m and 12m long) are outdoors, as well as a solarium.
  • The swimming pool was designed by the architect Louis Bonnier and built in 1922, as an extension to the former bathhouse, dating from 1908.
  • The swimming pool was historically heated by an artesian well of 580m in depth, which gave access to water at 28°C, and is now heated by the city’s district heating system. The heat generated by Stimergy’s digital boiler will allow equivalent savings to be made to this source of heating.

To find out more: / @StimergyFr