Amongst the 14 challenges that form the programs for 2004 2007, eight address sustainable development, notably in the reduction of energy consumption and greenhouse gas emissions or the development of renewable energies. 2 3 5 Managing impact on the environment 2 3 5 1 DISCHARGES... In renewable energies services, 2005 saw strong business development, mostly in heat pumps, with or without solar panels for the production of hot water. (2004: 15 000 ;2005: 30 000.