This paper aims to provide a measure of the average global occupancy cost per employee for a head office established in the Paris region. The research focuses on head office locations for large service firms in the Paris region, with particular emphasis on FIRE (finance, insurance, real estate) industries and other service industries such as legal, accounting and consulting firms.While occupiers generally refer to rent per sq.m. when looking for a new office location, this new measure of global occupancy cost per employee takes account of per-employee occupancy ratios. This research shows that although a new building has a higher rent per sq.m. than a second hand building, it is generally also more efficient and allows better optimization of surface use for the occupier. It is thus observed that putting the head office in a second hand building can ultimately be more expensive than in a new building.