TheObservatoire régional de l'immobilier d'entreprise en Île-de-France (ORIE) estimates that converting obsolete office space would create up to 150,000 housing units for 340,000 people in the Paris region. Of course, not all areas are created equal. That's why ORIE has identified three types of areas where office recycling is more or less feasible, based on a rating scale ranging from -1 to +1, combining tertiary dynamics, residential dynamics and economic feasibility.