The world of the 4th Industrial Revolution is underpinned by sharing and collaboration approaches. More and more, these are entering the mainstream and gradually putting aside the proprietary mindset and models of the past. Openness is what essentially unlocks these massive new opportunities. Openness can re-late to either the data itself or the access to it. In the following, we will review the subtle balance between these two approaches and consider their respective advantages and disadvantages. Although the basic concepts may be applicable across many thematic areas, we will focus here on the case of building data and the related efforts to provide for their openness.What is then the key driver for open data? With more data available than ever before the industry is presented with a new challenge (Dan Prairie et al., 2016). Device data is stored and communicated in many different formats. It has inconsistent, non-standard naming conventions, and provides very limited descriptors to enable us to understand its meaning. Simply put, the operational data from smart devices and equipment systems lacks information to de-scribe its own meaning. As a result, data from today’s devices, while technically “available”,is hard to use, thus limiting the ability for building operators to fully benet from the value contained in it. That is exactly where open data comes to our assistance.