Local Authorities worldwide are encouraging adaptation to reduce building related energy consumption and greenhouse gas emissions. The City of Melbourne is promoting the retrofit of 1,200 CBD properties before 2020 with sustainability measures as part of their policy to become a carbon neutral city, and the City of Amsterdam aims at cutting their CO2 emissions with 40% by 2025. In Amsterdam, the oversupply of office space makes across use adaptation, conversion from offices into housing, an interesting development. The concept of adaptation is well developed in Europe, though the scale of some of the post war developments has created different forms of building perhaps less adaptable or suited to change. The need to adapt buildings and to reduce environmental footprints becomes more pressing over time as global concentrations of carbon dioxide increase. Moreover, the ageing workforce and the new way of working lead to a decline in the demand of office space, and so conversion becomes a possibility for dealing with obsolete offices. Applying knowledge of adaptation to examine the adaptation potential of office buildings in Melbourne and Amsterdam, it is possible to learn where similarities and differences exist and where new practices can be shared. This paper addresses the question; what are the possibilities for building conversions in Melbourne and Amsterdam? Using Amsterdam and the Melbourne CBD as case studies, the research analysed the across use adaptation potential of office buildings in Amsterdam and in Melbourne CBD. The outcomes of this research show where similarities and differences exist and are relevant to all urban areas where adaptation of existing office buildings can mitigate the impacts of climate change and enhance the city for another generation of citizens and users.