||There is considerable interest in ‘open data’ with many administrations launching, or involved in, programmes to make government data open and available. From geographical information systems (GIS) to infrastructure data and building information models (BIMs), it is believed that access to this data will contribute to productivity and efficiency gains. Yet there remains uncertainty surrounding how stakeholders involved in design, construction and maintenance of the built environment might benefit from this unlocked information. We begin this paper by looking at a specific government initiative providing access to built environment datasets - we investigate and compare the different approaches for accessing this information-base. With speculation that open access will lead to huge benefits in productivity, particularly through interoperability, the second part of our paper implements a system to explore the federation of this data and the results of its interoperation in a collaborative visual environment. While prediction models continue to be problematic when simulating multiple complex and interdependent factors of the built environment concurrently, here we appropriate data and exploit it within decision-support systems. A Systems that provides a qualitative virtual 3D rendering of what is otherwise prosaic or opaque technical information, providing the potential to federate, align and compare otherwise disparate sources of data. Arguably access to open data has not revolutionized consumer computing, but it has played an important part in combination with the emergence of other technologies such as mobile devices, Wi-Fi and location aware computing. Here we critique ‘open data’ initiatives for design and construction, and ask what part they might play—in combination with other technologies—to help deliver on the promise of productivity.