Retrofit and adaptation of the existing building stock is an essential factor in man-kinds attempts to mitigate the effects of climate change and global warming. Pointedly most of the global stock was constructed with no consideration of sustainability. In Australia environmental sustainability for commercial buildings was legislated in the Building Code of Australia in 2006, with minimum standards for energy efficiency applied to new build and some retrofit projects. The City of Melbourne launched the 1200 Buildings Program in 2008 as a key strategy to deliver carbon neutrality by 2020 after Arup (2008) concluded that CBD 1200 commercial office retrofits, some two thirds of the total stock, would deliver a 38% reduction in greenhouse gas emissions. This research examined what has been undertaken in respect of the commercial retrofits undertaken as part of the 1200 Buildings Program. This study had two aims which were firstly; to gain a deeper understanding of the improvements made to existing office buildings in the 1200 Buildings Program and secondly, to undertake a comparison of current practice to identify similarities and differences in approach to retrofit within the 1200 Buildings Program. The case studies showed the sustainability measures undertaken were largely focussed on building services and energy efficiency. There was less work undertaken to address water economy measures, to the building fabric and little work, which addressed social sustainability aspects.