Although it has a relatively low profile, one method of increasing sustainability in buildings currently being considered is the provision of green roofs. Most importantly, green roofs have thermal benefits in reducing heat loss and reducing heat gain and also enhancing bio-diversity. Furthermore, green roofs can absorb some of the carbon emissions in the CBD. With the increasing emphasis placed on climate change and much of the emphasis placed on new buildings only, it is accepted that Australia needs to increase the adaptation of the existing commercial building stock (CSIRO, 2002 AECOM 2008). At the same time the city of Melbourne has launched the 1,200 building program which aims to refurbish 1,200 CBD properties before 2020 as part of their policy to become a carbon neutral city by 2020. This paper address the research question: what is the potential of existing buildings in the CBD to accommodate a retrofitted green roof? Furthermore how many buildings are suitable for green roofs? In the process of conducting the analysis this research examined 528 building surveyed in the Melbourne CBD in 2008 and 2009. The paper outlines the types of green roof which can be retrofitted to existing buildings. The outcomes of this research is applicable on a global basis and relevant to all urban centres where existing commercial buildings can become part of the solution to mitigate the impact climate change and enhance the city.