Traditionally studies of office occupiers location choice assume firms follow standard behavioural assumptions of neoclassical economics. Firms are thus assumed to be homogeneous and make rational profit maximising decisions. More recently research in this area has taken a more behavioural approach resulting in identifying a number of additional factors and the complex nature of the decision making process. This paper seeks to extend an understanding of commercial location decision making against a backdrop of sustainability and green buildings. It attempts to bring together the two distinct streams of research, namely location decisions of office occupiers and studies examining green buildings and sustainability. The study utilises evidence from one-to-one in-depth interviews with nine CBD office occupiers of sustainable or Green Star buildings. It highlights a range of factors that underpin the decision to occupy Green Star or sustainable offices. The results indicate that firms decisions are influenced by factors including cost, location, availability of accommodation, marketing and company culture and they also confirm that for many organisations sustainability issues play an important additional consideration.