Lighting energy management system and method

A method of controlling the operation of a plurality of lighting fixtures in a building in order to minimize the energy required by said lighting fixtures, said building having a plurality of physical zones, said energy management method comprising:

• (a) determining photo sensor data using at least one photo sensor, determining occupancy data within at least one of the physical zones using at least one occupancy sensor, and providing said photo sensor data and occupancy data over a communication bus;
• (b) providing signals to and from each of said lighting fixtures over the communication bus;
• (c) obtaining at least one personal lighting command and providing said at least one personal lighting command over the communication bus;
• (d) receiving photo sensor data, occupancy data and said at least one personal lighting commands over said communication bus, and storing and maintaining a plurality of zone objects and a plurality of fixture objects, wherein each zone object is associated with a zone of the building, each fixture object is associated with a lighting fixture and each fixture object is associated with a zone object according to whether said associated lighting fixture is within the zone of the building associated with the zone object such that:
• (i) each said zone object receives occupancy sensor data and selectively provides an adjustment command to at least one associated lighting fixture, so that the optimal brightness command reduces at least one associated lighting fixture in brightness when the zone is determined to be unoccupied;
• (ii) each said fixture object receives at least one of a personal lighting command and data from said associated zone object, determines a desired brightness level, uses the desired brightness level and a load shedding factor to determine a target brightness level, uses the target brightness level along with photo sensor data to determine an optimal brightness command which takes into account daylight illumination;
• and
• (e) distributing the optimal brightness command received from each of said fixture objects to each said associated lighting fixtures, such that the energy required by the light fixtures is minimized according to several individual energy management strategies and personal lighting preferences.

A method of determining the relative physical location of a plurality of device nodes interconnected with cabling within an electrical system and representing said relative physical location using a branch mapping that represents cable lengths between pairs of nodes, said method comprising:

• (a) measuring the power supply voltage at each node;
• (b) selectively and alternately increasing the current consumption for each node by a predetermined amount;
• (c) determining the corresponding decrease in the power supply voltage within said node and said other nodes that results due to resistive losses within the cabling;
• and
• (d) determining the physical cable length between each pair of said nodes and the relative physical location of each of said nodes.

A method of determining the relative physical location of a plurality of device nodes interconnected with cabling within an electrical system and representing said relative physical location, said method comprising:

• (a) measuring the power supply voltage at each device node,
• (b) sorting said power supply measurements and determining a sequence of physical installation locations based on the sorted power supply measurements;
• (c) comparing said sequence with a likely sequence of installation based on the physical construction of said electrical system;
• (d) determining the relative physical location of each of said nodes.

A method of performing daylight compensation within a lighting energy management system wherein the daylight contribution to a particular lighting level as read by a photo sensor associated with at least one lighting fixture is determined by:

• (i) operating each of the lighting fixtures at a range of brightness levels when there is no adverse change in available daylight;
• (ii) compiling the readings of said photo sensor for each brightness level of each lighting fixture into a reading profile for the photo sensor;
• and
• (iii) for the particular lighting level, using said reading profile to remove the photo sensor readings associated with the brightness level for each lighting fixture from said lighting level, such that for the particular lighting level, the daylight contribution can be determined;
• (iv) adjusting the light provided by each lighting fixture to compensate for the daylight contribution as determined in step (iii).

A method of controlling the operation of a plurality of energy consuming units in a building using a plurality of local switching devices that reduces switching stress due to excessive inrush currents normally associated with said energy consuming units and reduces energy consumption, each energy consuming unit having an associated power supply and an inrush current limiting impedance, said method comprising:

• (a) distributing the centralized switching control by electrically coupling each of said local switching devices between an associated energy consuming unit and an associated power supply;
• (b) locating each of said switching devices in close proximity to each of said energy consuming units so as to increase inrush current limiting impedance associated with said energy consuming unit;
• (c) communicating a connectivity command to said switching devices over a communication bus;
• and
• (d) selectively switching each energy consuming unit using said switching device based on the connectivity command.

A method of installing a lighting control device and associated data communication wiring and power wiring within a lighting fixture cover having knock-out aperture formed within, said method comprising:

• (a) installing said data communication wiring outside said lighting fixture cover above the position of said knock-out aperture;
• (b) installing said power wiring within said fixture cover below the position of said knock-out aperture;
• and
• (c) positioning and removeably securing said lighting control device within said knock-out aperture such that said lighting control device represents an electrical barrier between the inside of said light fixture cover and the outside of said light fixture cover.