Raised on a small plot off Rue Cugnot in Saint-Étienne, this building is a solid 16-floor structure designed to house flats, offices and retail stores and to be operated at significantly reduced cost. The energy bill for residents will amount to €0. The building's energy balance is positive thanks to around 1,400 m2 of solar panels on the facades and roof, a rainwater harvesting system for use, and a "triple-flow" hybrid ventilation solution.