Computer software for optimizing energy efficiency of a lighting system for a target energy consumption level

• US 5,812,422 A
• Filed: 09/07/1995
• Issued: 09/22/1998
• Est. Priority Date: 09/07/1995
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Lyons, Damian M.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Fiul, Dan
• Application Number:
  US08/524,979
• Time in Patent Office: 1,111 Days
• Field of Search: 395/500, 395/750, 395/200.05, 395/200.06, 395/221.9, 395/619, 395/200.1, 315/307, 315/156, 362/85, 364/512, 364/578, 364/139, 364/480, 364/481, 364/482, 364/483, 364/143, 364/146, 364/145, 364/492, 364/493, 364/505
• US Class Current: 703/18
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A method for optimizing the energy efficiency of a lighting system including a plurality of light sources, which includes the steps of defining a set of parameters for the lighting system, and using a linear programming technique, taking into account the set of parameters, to produce energy allocation output data which satisfies a total energy consumption constraint that the total energy allocated to the lighting system not exceed a target energy consumption level, and which is representative of an optimal allocation of energy to each of said light sources. The lighting system is installed in a building which includes a plurality of rooms each of which is equipped with at least one of the light sources. In general, the lighting optimization problem is translated into a linear programming problem by formulating a set of lighting system energy allocation constraints, converting these constraints into a set of constraint equations and a cost function, converting the constraint equations into a set of simultaneous linear equations, and then solving the set of simultaneous linear equations in such a manner as to minimize the cost function, to thereby produce the energy allocation output data, which is preferably in the form of an optimal brightness level for each light source. These steps are preferably implemented in computer software, which is preferably loaded in a programmable central controller of an intelligent lighting control system which is responsive to the energy allocation output data for automatically adjusting the brightness level of each of the light sources to the optimal brightness level therefor. Preferably, available energy remaining after satisfying minimum brightness levels for each room is allocated at least partially on the basis of the designated priority level of each room, and/or the energy efficiency of the light sources.

Claims

1. A method for optimizing the energy efficiency of a lighting system including a plurality of light sources, including the steps of:

defining a set of parameters for the lighting system; and

,

using a linear programming technique, taking into account said set of parameters, to produce energy allocation output data which satisfies a total energy consumption constraint that the total energy allocated to the lighting system not exceed a target energy consumption level, and which is representative of an optimal allocation of energy to each of said light sources.

2. The method as set forth in claim 1, wherein the using step is carried out by formulating a linear programming problem in terms of a set of lighting system energy allocation constraints, converting said constraints into a set of constraint equations and a cost function, converting said constraint equations into a set of simultaneous linear equations, and then solving said set of simultaneous linear equations in such a manner as to minimize said cost function, to thereby produce said energy allocation output data.

3. The method as set forth in claim 1, wherein the using step is carried out by formulating a linear programming problem which includes a set of constraint equations representative of a set of lighting system energy allocation constraints, and a cost function representative of lighting system energy consumption, and then solving said linear programming problem in such a manner as to satisfy said total energy consumption constraint and each of said lighting system energy allocation constraints, while minimizing said cost function.

4. The method as set forth in claim 2, wherein said set of parameters includes a minimum and maximum brightness level for each of said light sources, and said set of lighting system energy allocation constraints includes a brightness range constraint that a brightness level of each of said light sources not be less than said minimum brightness level nor greater than said maximum brightness level.

5. The method as set forth in claim 4, wherein said energy allocation output data includes an optimal brightness level for each of said light sources.

6. The method as set forth in claim 5, wherein each of said light sources has a linear power efficiency coefficient representative of the energy efficiency thereof, and said set of lighting system energy allocation constraints includes a constraint that available energy be allocated to each of said light sources at least partially on the basis of said linear power efficiency coefficient thereof, with more energy efficient ones of said light sources being allocated more of said available energy than less energy efficient ones of said light sources.

7. The method as set forth in claim 5, wherein the lighting system is installed in a building which includes a set of rooms each equipped with at least one of said light sources, said set of parameters includes a designated priority level for each of said rooms, and said set of lighting system allocation constraints includes a constraint that available energy be allocated to each of said rooms at least partially on the basis of said designated priority level thereof, with higher priority ones of said rooms being allocated a greater amount of said available energy than lower priority ones of said rooms.

8. The method as set forth in claim 5, wherein said set of lighting system energy allocation constraints further includes an equal priority-equal energy constraint that said at least one light source in rooms with an equal priority level designation will be allocated an equal amount of available energy.

9. The method as set forth in claim 7, wherein said set of rooms includes a utility room and at least one connected room served thereby, and further comprising the step of processing said energy allocation output data to determine whether said optimal brightness level for each said connected room is equal to said minimum brightness level, and, if so, adjusting said optimal brightness level for said utility room to said minimum brightness level.

10. The method as set forth in claim 1, wherein said energy allocation output data includes an optimal brightness level for each of said light sources, and further comprising the step of using said energy allocation output data to adjust a brightness level of each of said light sources to said optimal brightness level.

11. A computer system comprising:

a processor; and

computer software embodied in a storage medium, comprising;

lighting optimization means for defining a set of parameters for a lighting system having a plurality of light sources and a set of linear programming equations; and

,

linear programming means for solving said linear programming equations in such a manner as to produce energy allocation output data which satisfies a total energy consumption constraint that the total energy allocated to the lighting system not exceed a target energy consumption level, and which is representative of an optimal allocation of energy to each of said light sources.

12. The computer system as set forth in claim 11, wherein said set of linear programming equations includes a set of constraint equations representative of a set of lighting system energy allocation constraints, and a cost function representative of lighting system energy consumption.

13. The computer system as set forth in claim 12, wherein said linear programming means converts said set of constraint equations and said cost function into a set of simultaneous linear equations, and solves said set of simultaneous linear equations in such a manner as to satisfy said total energy consumption constraint and each of said lighting system energy allocation constraints, while minimizing said cost function.

14. The computer system as set forth in claim 13, wherein said set of parameters includes a minimum and maximum brightness level for each of said light sources, and said set of lighting system energy allocation constraints includes a brightness range constraint that a brightness level of each of said light sources not be less than said minimum brightness level nor greater than said maximum brightness level.

15. The computer system as set forth in claim 14, wherein said energy allocation output data includes an optimal brightness level for each of said light sources.

16. The computer system as set forth in claim 15, wherein each of said light sources has a linear power efficiency coefficient representative of the energy efficiency thereof, and said set of lighting system energy allocation constraints includes a constraint that available energy be allocated to each of said light sources at least partially on the basis of said linear power efficiency coefficient thereof, with more energy efficient ones of said light sources being allocated more of said available energy than less energy efficient ones of said light sources.

17. The computer system as set forth in claim 15, wherein the lighting system is installed in a building which includes a set of rooms each equipped with at least one of said light sources, said set of parameters includes a designated priority level for each of said rooms, and said set of lighting system allocation constraints includes a constraint that available energy be allocated to each of said rooms at least partially on the basis of said designated priority level thereof, with higher priority ones of said rooms being allocated a greater amount of said available energy than lower priority ones of said rooms.

18. The computer system as set forth in claim 17, wherein said set of lighting system energy allocation constraints further includes an equal priority-equal energy constraint that said at least one light source in rooms with an equal priority level designation will be allocated an equal amount of available energy.

19. The computer system as set forth in claim 17, wherein said set of rooms includes a utility room and at least one connected room served thereby, and further comprising an output filter module for processing said energy allocation output data to determine whether said optimal brightness level for each said connected room is equal to said minimum brightness level, and, if so, adjusting said optimal brightness level for said utility room to said minimum brightness level.

20. An intelligent lighting control system for a lighting system having a plurality of light sources, comprising:

a programmable controller;

computer system loaded into said programmable controller, said computer system including a lighting optimization code which defines a set of parameters for the lighting system and a set of linear programming equations, and a linear programming code for solving said linear programming equations in such a manner as to produce energy allocation output data which satisfies a total energy consumption constraint that the total energy allocated to the lighting system not exceed a target energy consumption level, and which is representative of an optimal allocation of energy to each of said light sources; and

,

wherein said programmable controller is responsive to said energy allocation output data for automatically controlling a brightness level of each of said light sources.