Visual alerts in a lighting network

A controller for controlling a battery-powered luminaire in a lighting network, the controller comprising:

• a network interface for communicating with the lighting network;
• and
• control logic for controlling at least one illumination source of the battery-powered luminaire;
• wherein the control logic is configured to:
• detect a failure of at least one mains-powered luminaire in the lighting network, determine that the mains-powered luminaire was emitting or had been instructed to emit a visual alert when the failure occurred, and control the at least one illumination source of the battery-powered luminaire to assume an alert role, if it is not yet emitting a visual alert, or, if it is emitting an initial version of a visual alert, to modify the initial version of the visual alert and emit such modified version of the visual alert in response, the failure being detected based on a loss of communication, within the lighting network, with the mains-powered luminaire.