The mission began with a “large company” energy audit imposed by article 8 of European directive 2012/27/EU on energy efficiency. Despite a recent renovation of the envelope as well as a renovation of the techniques, the audit brought to light an abnormally high energy consumption, as well as avenues for improvement to significantly reduce the energy consumption of the building. We then accompanied the client in the implementation of the audit action plan, and proposed that part of our remuneration be linked to the savings actually achieved through the implementation of an Energy Performance Contract of 4 years.