In our talk we show how we use PI as an IOT Platform for smart building operation. As soon as information about a building is readily available and consumable with various client applications, topics like energy saving, building usage optimization etc. can be easily tackled. PI is the foundation layer for all these topics in our environment, and we can both get fast access to all kinds of data thanks to the multitude of interfaces and connectors available, as well get a metadata structure implemented in PI AF - in some cases even automatically. Our energy savings use case was implemented with the tools from Seeq,