Imagine a building that generates more electrical energy than it consumes! Bouygues Immobilier designed the Green Office Meudon as a pioneering concept in 2001. Nine years later, Bouygues Energies & Services won the contract to operate the site, in the form of an energy performance contract. To optimise the building’s energy consumption, nine distinct uses of energy are analysed (heating, lighting, air conditioning, etc.). The results are conclusive: after the first year of operation, the building was generating more energy from renewable sources than it was consuming.