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Acronym for Local Area Network. A defined network providing the physical infrastructure for device communication.



Light Emitting Diode. is a semiconductor device that emits narrow-spectrum light when electrically biased in the forward direction.



(Leadership in Energy and Environmental Design): A voluntary, consensus-based national standard for developing high-performance, sustainable buildings. -



Lighting includes both artificial light sources such as lamps and natural illumination of interiors from daylight (see Daylighting). Lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide. Artificial lighting is most commonly provided today primarily by electric lights. Proper lighting can enhance task performance and aesthetics. Indoor lighting is typically generated from a form of fixture and a key part of architecture and interior design.


Lighting Control

Devices which give you flexibility, decorative effects and multiple uses from your lighting sources. Today’s sophisticated dimming systems enable you to lower the light level to conserve energy and increase bulb life; vary the mood of a room; alter light source intensity; create lighting scene in each room. Types of controls include lighting control systems, integrated dimming systems, touch dimmers, slide dimmers and rotary dimmers.


Lighting Control System

Lighting control system consists of a device, typically an lighting controller (or computer), that controls electric lights for a building. Lighting control systems usually include an interface to a Building Automation System. These interfaces allow users the ability to switch power to lights, dim lights, and program lighting levels. A major advantage of a lighting control system over conventional lighting is the ability to control any device from any interface. Additionally, lighting control systems provide the ability to automatically power a device based on programming events such as:

Chronological time (time of day) - "Scheduling"

Astronomical time (sunrise/sunset)

Room occupancy - occupancy override

Setpoint adjustment

Events Alarm conditions

Program logic - Building Automation System (programmatic combinations of events)


Line Voltage Systems

120 volt distribution is used mostly for lighting mounted to the outside of a house or for post-top lanterns along a drive or path. Line voltage landscape lighting can provide more light and handle greater distances than low voltage systems, but the installation is less flexible and more costly.


Load Shedding

See Demand Limiting


Low Voltage Fixtures

Recessed track, task, decorative or landscape fixtures for low voltage lamps. A transformer is required for these fixtures and may by integrated, local or remote.



Building Control protocol developed originally by Echelon Corporation and now defined in ANSI/CEA 709.1 – used within the LonWorks platform for network communications – primarily within building control. Defined to operate in a free topology network configuration with a twisted pair transceiver or work with a powerline transceiver.


• Networked communication in building control/factory automation



A logo applied to LonWorks devices that have been certified to the interoperability standards of LonMark International.


LoNmark International

LonMark International is the organization of LonWorks developers, system integrators, and end-users that define standards to ensure interoperability between LonWorks devices from multiple manufacturers.



LonWorks is an open protocol that was originally developed by Echelon Corporation. It is now maintained by Echelon in collaboration with members of the LonMark Interoperability Association. It requires the use of Echelon's Neuron microprocessor to encode and decode the LonWorks packets.

The LonWorks protocol is based on the concept of using standardized functional profiles to control similar pieces of equipment. OEM translators are LonWorks compatible devices, but are not LonMark devices. A LonMark device has been thoroughly tested by Echelon ( and has been given the LonMark logo indicating compliance with the LonWorks profile specification. All LonMark devices require the use of proprietary hardware manufactured by Echelon Corp. In order to reduce the cost of adding that hardware on every translator, OEM formats the data packets in a manner specified by the LonWorks documentation and hands them off to the LonWorks Option Card.


LonWorks' aim is to provide developers, from the same or different companies, the ability to design products that will be able to interact with one another. The LonWorks protocol provides a common applications framework that ensures interoperability using powerful concepts called network variables and Standard Network Variable Types (SNVTs).


Communication between nodes on a network takes place using the network variables that are defined in each node. The product developer defines the network variables when the application program is created as part of the Application layer of the protocol. Network variables are shared by multiple nodes.


The use of Standard Network Variable Types (SNVTs) contributes to the interoperability of LonWorks products from different manufacturers. If all manufacturers use this variable type in their application when a network variable for continuous level is defined, any device reading a continuous level can communicate with other devices on the network.


Low Voltage Housing

Recessed housing with an integral, or occasionally, remote transformer.


Low Voltage Lamps

Incandescent lamps that operate at 6, 12 or 24 volts. Low voltage lamps require a step-down transformer to reduce the voltage from the normal household 120 volts.


Low Voltage Lighting System

A type of lighting that operates on 12-volt current rather than the standard 120 volts. Power is supplied by a transformer, which is itself connected to 120-volt power.


Lumens (symbol: lm)

The amount of light that a bulb produces. Unit of output; technically “Luminous flux.”