Verification device for a connected lighting system

A verification device to detect malfunction in a connected lighting system, the connected lighting system comprising multiple luminaires and multiple occupancy sensors, the verification device comprising: - an input interface (301) arranged to connect to a database and obtain the sensor data obtained from the multiple occupancy sensors, - an aggregation unit (310) arranged to compute occupancy values which are indicative of occupancy over a specified time period at different hierarchical levels by applying a statistical measure, and - a processing unit (320) arranged to compare an occupancy value at a lower hierarchical level with an occupancy value at a higher hierarchical level, finding deviations that indicate a malfunction in the connected lighting system and producing a signal to communicate the malfunction.