The system, if implemented with a number "n" of presence detectors, allows to monitor the accesses of the supplier in the different rooms of the building to be controlled by measuring the time spent by the maintenance operators in these areas. Each operator involved in the work carrying out his duties taking with him his cell phone smartphone with Bluetooth connection activated at the end of the intervention will be associated with the areas in which he will operate with indication of the timing dedicated to them. The performance data communicated to the companies can not however be used for disciplinary sanctions of the employee.