case of a fire alarm or loss of normal power the lighting control system may
turn on key emergency lighting fixtures.
Data and information from a lighting system are also an integral part of an
overall energy strategy and at a given facility or business level, need to be con-
sidered with HVAC systems, metering and building plug loads. Monitoring the
number of hours that the lights are operated and the number of times that
lights are turned on provides information to estimate lamp life, which can be
used to schedule group relamping.
Lighting control systems may use several different communications proto-
cols. One communication protocol called the Digital Addressable Lighting
Interface (DALI) was specifically developed for ballasts and relay switches in
the 1990s. For a DALI implementation each lamp uses a dimming ballast
and each lamp has its own network address. DALI uses a two-wire, low-volt-
age wiring scheme in a bus topology with the bus providing both power and
control signals to the ballast.
DALI is an open-source protocol based on standard IEC60929 which spe-
cifies performance requirements for electronic ballasts. Each DALI controller
(called a busmaster) can handle up to 64 addresses and 16 groupings. Because
the DALI protocol is solely for use by lighting control systems, the integration
of a DALI lighting control system to other building automation systems
requires a protocol translation with systems using BACnet or LonWorks.
DALI has been extended into shading control and wired network connectivity
has been supplemented with wireless connectivity.
Overall lighting control systems are increasingly using structured cable,
Ethernet, and TCP/IP protocols at least at the higher levels of the control sys-
tem—all of which are foundations for a smart building.
Lighting Control Systems 57