An apparatus for controlling the lighting of an environment on the basis of contributions to a total illumination from both daylight and artificial light, comprising an illumination controller comprising: - a light sensor device comprising a first light sensor arrangement configured to sense light within a first spectral range including non-visible light and excluding a sub-range constituted by at least a major part of the visible light, and a second light sensor arrangement configured to sense light within a second spectral range including at least a part of said sub-range; and - a control unit connected with the light sensor device and arranged to determine an amount of daylight on the basis of an output signal of the first light sensor arrangement and a predetermined function, which characterizes the relationship between the spectral power distribution of the infrared spectrum of daylight and the spectral power distribution of the visible spectrum of daylight, and to determine an amount of artificial light on the basis of a comparison of an output signal of the second light sensor arrangement and the output signal of the first light sensor arrangement; - wherein the illumination controller is arranged to control illumination on the basis of said comparison of amounts of daylight and artificial light; and - wherein the apparatus is connectable with a set of lighting devices, including at least one lighting device, for controlling the light output of the set of lighting devices, characterized in that - the apparatus is further connectable with window blinds for controlling their setting; and - the apparatus is arranged to increase an illuminance of the environment by primarily controlling the window blinds and secondarily controlling the set of lighting devices. - a light sensor device comprising a first light sensor arrangement configured to sense light within a first spectral range including non-visible light and excluding a sub-range constituted by at least a major part of the visible light, and a second light sensor arrangement configured to sense light within a second spectral range including at least a part of said sub-range; and - a control unit connected with the light sensor device and arranged to determine an amount of daylight on the basis of an output signal of the first light sensor arrangement and a predetermined function, which characterizes the relationship between the spectral power distribution of the infrared spectrum of daylight and the spectral power distribution of the visible spectrum of daylight, and to determine an amount of artificial light on the basis of a comparison of an output signal of the second light sensor arrangement and the output signal of the first light sensor arrangement; - wherein the illumination controller is arranged to control illumination on the basis of said comparison of amounts of daylight and artificial light; and - wherein the apparatus is connectable with a set of lighting devices, including at least one lighting device, for controlling the light output of the set of lighting devices, - the apparatus is further connectable with window blinds for controlling their setting; and - the apparatus is arranged to increase an illuminance of the environment by primarily controlling the window blinds and secondarily controlling the set of lighting devices.