Adaptive integrated daylight and electric light control with multi-sensor for controlled-light distribution

#This invention relates to lighting controls and, more particularly, to a method and a system for controlling light distribution in a space including multiple installed light sources and an external light source.

#Current building control systems for controlling electric light and daylight mostly use independent control systems. Integrated control of daylight and electric light appears to the next step of modern lighting control strategies. Recently, ‘integrated’ control systems have been disclosed in some U.S. patents. The following are two examples.

#U.S. Pat. No. 7,111,952 B2 discloses a combined controller for window treatments and electric lights. This system includes daylight sensing to control the dimming levels of the electric lights and the amount of daylight in the room. This system uses a central controller to control the subsystems. However, the operation is sequential, i.e., first window treatments are adjusted until fully open/closed, and then electric lights are adjusted to provide the remaining required light.

#In general, the various aspects of the invention may be combined and coupled in any way possible within the scope of the invention. The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

#FIG. 1 shows a high level diagram of a lighting control system according to an embodiment of the invention.

#FIG. 2 shows a high level diagram of a lighting control system according to another embodiment of the invention.

#Certain embodiments herein describe a system and method for providing a uniform or controlled light distribution by integrating control of daylight and electric light from one or more lighting fixtures. The integrated control system may advantageously be based on minimizing the mean-squared error of the measured luminance at the sensor sampling points and minimizing an energy cost function.

#In a space having multiple controlled light fixtures, the light fixtures could be in a single office (uniform lighting in a space) or task lights for non-uniform distribution (multiple offices such as cubicles or single offices with task lights). Multiple sensors may be installed to sample the light levels in various locations throughout the space. An integrated closed-loop control algorithm then adjusts the light levels from each light fixture and controls window treatments in such a way that an overall desired light distribution and energy reduction is achieved.

#FIG. 1 shows an embodiment of the implementation described herein. The system in FIG. 1 includes a central controller 102, which receives inputs from photo sensors 121, 122, 123 for a space and from a photo sensor 104 for external light (e.g., sunlight). User input 101 (User setpoint input) and sensor data from the sensors 104, 121, 122, 123 are processed by the central controller 102 to produce an appropriate operating condition, and accordingly the central controller 102 adjusts the intensity of electric lights 111, 112 and controls the window treatments 103 to modify the amount of external light entering into the space. Note that reference to “sunlight” does not limit the light exterior to the space as sunlight. Photo sensor for sunlight 104 may sense any light exterior to the space or specific to a source of light.