1.1 Framework of this study: the GLN project In the framework of the TETRAENER European project, the "Genève Lac Nation" project aims to use the cold water of the Lake of Geneva. for meeting the refrigerating needs of the administrative buildings (mainly international organizations) in a suburb district of the Geneva city. Cold lake water will be pumped at a depth of around 35m, and distributed through a district cooling loop without intermediate further cooling. The temperature stays at around 7-9 °C all along the year. Around 30 buildings of big or medium size will be concerned, covering an area of more than 1 km². Geneva's Government has ruled in favour of “Genève Lac-Nations” by a decision of the State Council (Executive) in early 2003. The Parliament has also initiated various studies and building loans (by adopting ad hoc laws). The main partners are: • The State (Canton) of Geneva, • The City of Geneva • The Building Foundation for International Organisations - FIPOI • Services industriels de Genève – SIG (fluid distributors) The latter (SIG), is the main utility in Geneva for Electricity, Gaz and Water distribution (including also District Heating networks). It is the executive organism which will construct and exploit the district cooling installations. As a semi-private company, it has to manage the installations and develop a commercial marketing in order to sell the GLN concept to the different potential customers, in a way that it can degage some profits. The GLN network will be able to distribute a global power of 17 MW of renewable cold energy (2'700 m3/h). It is expected to save around 1'500 tons/year of ultra-light oil (∼ 20% of the heating capacity) and 4'800 tons of CO2. As this network can also serve as a cold source for heat pumps in winter, in medium term the electricity savings in summer are expected to be compensated by the Heat pumps consumptions.