The city of Lausanne has the ambition to realize an eco-district on the Plaines-du-Loup according to the standard "2000 Watt society". The beginning of the construction work is scheduled for 2018. To achieve this standard, the heat balance plays a key role. Various options are being considered for heating.
One of the most promising solutions is the implementation of heat pumps (HP) coupled with deep geothermal probes (between 500 to 800 m). However, if the construction and operation of HP with traditional geothermal probes down to 150-200 meters are well controlled, extending to depths of the order of 500 meters and more implies an important process of reflection and optimization.
To have some experience before investing in this technology for the entire eco-district, the city of Lausanne, through the Services industriels (SiL), launched in 2011 a demonstration project, called Sirius, on a small district project of 4 buildings with 8 deep geothermal probes of 500 meters deep.
The project started effectively in 2012 with the drilling of the first geothermal double-U probe and heat was delivered by the system in autumn 2014.
Due to his demonstration component, a fiber optic distributed temperature system (DTS) was chosen for the temperature measurements of the geothermal field to calculate balances at different depth levels of the probe and then to assess the performance of the geothermal probe.
