Considerable guidance is available to the building industry for increasing the sustainability of individual refurbishment and redevelopment projects. However, there is very little information to allow a direct comparison of refurbishment and redevelopment options. Part 1 of this paper summarises the findings of a recent DTI funded research project to investigate sustainability of the two options. It describes: 1 - the method developed by BRE within the project to compare the environmental and whole life costs of refurbishment and redevelopment 2 - key findings arising from the research 3 - a simple online tool, Office Scorer, developed within the project, which allows users to compare refurbishment and redevelopment scenarios for a particular site. Part 2 of this paper contains case studies from the use of Office Scorer. 8 pages.