Human habitation often requires augmentation of natural ambient lighting with artificial lighting. For example, many office spaces, commercial spaces and/or manufacturing spaces require task lighting even when substantial amounts of natural ambient lighting are available. For many of these uses, the level of the light may be specified by one or more regulatory authorities. Hence, when natural ambient light is available, ambient and task lighting should be integrated such that they do not work against one another. For example, natural ambient lighting should not be distracting to the task(s) to be performed in the lighted space. An example is discussed later that utilizes ambient light sensing, that includes sensing of any natural ambient light or the like that may be available, to adjust the control of the artificial lighting device(s). Ambient light sensing detects at least some light that is present in the space even if the controlled artificial lighting were absent or turned OFF; although depending on the sensor/detector configuration, some of the controlled artificial lighting may also be detected. For ease of illustration and discussion, however, this initial example assumes only artificial lighting.

Hence, in our first example, the space 1 is an enclosed room or the like and is shown without windows or any other means of providing daylighting from an exterior of the building to the room space 1. In many actual installations, the space will include a window, skylight or other daylighting device configured to allow some amount of sunlight to enter the space. However, for its intended purpose or usage, the space requires at least some artificial lighting. Hence, the space 1 can be illuminated as/when desirable by at least one lighting device that produces artificial light during at least some times of occupancy.