The built environment contributes 40% to total global greenhouse gas emissions and 87% of the buildings we will have in 2050 are already built. If predicted climate changes are correct we need to adapt existing stock sustainably. Reuse is an inherently sustainable option, which reduces the amount of waste going to landfill. Inevitably settlements and areas undergo change, whereby land uses become obsolete and buildings vacant. At this stage, the options are either to demolish or to convert to another use. In central business districts (CBDs) outside of Australia there is a long history of office to residential conversion. Although these types of conversions are few in number in the Sydney CBD, a trend is emerging in conversion. Some 102,000m2 of office space is earmarked for residential conversion in Sydney as demand for central residential property grows and low interest rates create good conditions. Coupled with this, is a stock of ageing offices and a population projected to increase by 4% to 2031 requiring 45000 new homes. With the Sydney market about to be flooded with the Barangaroo office supply in 2017, the conditions for residential conversion are better than ever. _Based on the foregoing, this paper aims at answering the questions: which drivers drive residential conversions in Sydney? And what are the barriers for successful conversions? This paper investigates the nature and extent of residential conversion in Sydney, as well as the drivers and barriers to successful conversion. Through an extensive literature study, the paper identifies the key lessons from international residential conversion projects. Subsequently, expert interviews are held with developers in the Sydney market. This paper explores the potential of delivering sustainability to the Sydney CBD through residential conversion.