The invention relates a system for determining a change in a room (1). The invention comprises in particular a self-teaching illuminating system which detects a presence of an individual in an illuminated area. The system comprises lighting means (2) which output light, control means (3) which control the luminous output from the lighting means (2), measuring means (4) which determine a luminous intensity, and an evaluation means (6) which evaluates the luminous intensity determined by the measuring means (4). The evaluation means (6) is designed to detect a change of an object/individual in the room (1), starting from a determined luminous intensity at at least one first time, at which the lighting means (2) outputs no light, and a luminous intensity at at least one second time, at which the lighting means (2) outputs light.