Sky camera system for intelligent building control

A method comprising: receiving first camera images of a sky section at a first time, wherein each of the first camera images is acquired from a different camera of multiple cameras 170 placed at different camera positions; receiving second camera images of the sky at a second time from the multiple cameras; determining a sky condition at the first time in the first camera images; determining a sky condition at the second time in the second camera images; and predicting light levels at a location of interest at a future time based on the sky conditions. The location of interest may be a side of a building or a window on a building, and the sky conditions may be used to adjust a window covering 130 or a variable glass at said location 140.