Buildings produce lots of data: the building management system keeps track of the temperature, the ventilation unit measures CO2 levels and the security system knows if someone is present. All this data is useful on its own, but connect the data with each other, and the results are extremely powerful! Suddenly, one knows the amount of energy it takes the installation to create a comfortable and healthy indoor climate. One can make cleaning rounds more efficient by designing it on occupancy patterns. And best of all, one can automatically set out actions for improvement. Like an email to the concierge telling him to rinse down the water tap in order to prevent legionella.