Method, apparatus, and non-transitory computer-readable recording medium storing program for estimating operator

An apparatus for estimating an operator of multiple electrical devices, the multiple electrical devices being installed in a building, the apparatus comprising:

• a memory storing a program;
• and
• control circuitry that executes the program to:
• receive, from each of the multiple electrical devices, an operation log indicating that a corresponding electrical device was operated, the operation log including i) an ID of the corresponding electrical device and ii) a time at which the corresponding electrical device was operated;
• receive first positional information indicating a current position of a first terminal of a first user, the terminal of the user being carried or worn by the first user;
• determine, in a case where a distance between the current position indicated in the first positional information and a position of the building is a predetermined distance or less, that the first user entered the building from outside of the building;
• and
• estimate that the first user is an operator of a first electrical device based on the time at which the first electrical device was operated as recorded in a first operation log received from the first electrical device, when it is determined that the first user entered the building from outside of the building.