The new building was conceived by a multidisciplinary team, directed by Mr. Jesus Mª Susperregui, director of ACXT (the architecture firm of IDOM group). The idea used has implied an essential qualitative leap in terms of energy efficiency, internal comfort and water saving. Over 500 professionals are working in it right now. The new corporate office in Madrid was conceived with a clear aim: to host the activity of the company, represent it and to become its true “calling card”. The building was designed, from the very beginning, in a multidisciplinary environment, where architects and engineers have both shared decisions on architecture, building services and energy and communication systems. In this sense, the quest for solutions that would overcome the traditional salubriousness and comfort conflicts typical of tertiary sector buildings has been a fixed objective throughout the whole creation process. A salubrious and domestic atmosphere was thought of for a space destined for work. The building services have been planned seeking to maximize energy efficiency following a sustainable strategy. The building envelope includes a series of engineered elements focused on minimizing the building’s energy consumption. Its orientation, optimization of openings, high thermal insulation, high performance window panes, exceptional sun protection and double green skin both on the façade and on the roof are some of the features that follow this line of action.The main HVAC system is the structure itself for the building has an active structure (TABS: Thermally Activated Building System). This system, never before used in Spain, is combined with an evaporative night cooling and offers important advantages against traditional HVAC systems, significantly reducing consumption (saving 75% of the overall energy) and considerably improving the comfort of its occupants. Natural ventilation through interior communication atriums that function as chimneys can even override mechanical ventilation when the weather conditions are suitable. The ventilation ducts are made of fabric, which can be easily cleaned, thus guaranteeing a high level of salubriousness to its occupants. Water management is also naturally incorporated into the building’s routine. 100% of rain water is collected and used in the watering system, in the treatment and use of sanitary water and in the structure’s evaporative cooling system.