  Public educational systems operate thousands of buildings with vastly
different characteristics in terms of size, age, location, construction,
thermal behavior and user communities. Their strategic planning and sustainable
operation is an extremely complex and requires quantitative evidence on the
performance of buildings such as the interaction of indoor-outdoor environment.
Internet of Things (IoT) deployments can provide the necessary data to
evaluate, redesign and eventually improve the organizational and managerial
measures. In this work a data mining approach is presented to analyze the
sensor data collected over a period of 2 years from an IoT infrastructure
deployed over 18 school buildings spread in Greece, Italy and Sweden. The
real-world evaluation indicates that data mining on sensor data can provide
critical insights to building managers and custodial staff about ways to lower
a building's energy footprint through effectively managing building operations.
