According to the California Energy Commission, scheduling a building’s
lighting to automatically shut off at the end of the workday has been
documented to result in 5-10 percent kWh savings and 0-5 percent peak kW
savings. Scheduling the lighting to automatically shut off selected
lighting during peak demand periods has been documented to generate 5-15
percent kWh savings and 5-15 percent peak kW savings.
control panels or lighting automation panels—lighting control panels
that include an internal time-clock for scheduling capability—can be
used to generate energy savings and satisfy the mandatory controls
requirements in ASHRAE/IES Standard 90.1-2001.
Lighting control panels have been the subject of increased interest
within the electrical construction industry because of their
energy-saving utility and also new energy codes enacted in recent years.
The ASHRAE/IES 90.1 Standard, which was recognized by the Department of
Energy as the minimum national energy standard, requires automatic
shut-off in buildings larger than 5,000 sq.ft. except for buildings
where it is critical that the lighting be operated continuously. There
are basically three choices to satisfy this requirement: occupancy
sensors, building automation systems, and lighting control panels.
panels—also called switching or dimming panels, controllers, sequencers
and automation panels—are typically installed in the electrical room
near the electrical panel, although in some cases the electrical panel
and the lighting control can be integrated into a single unit using
The control panel
houses high densities of switching modules, although some can also house
dimming modules. Its processor assigns these modules to control zones—a
fixture or group of fixtures that are to be controlled in unison.
Otherwise, the control panel is a simple input/output device. Inputs can
include signals from manual controls, photosensors, PCs and other
devices. Outputs include switching or dimming of connected loads.
Different sizes are available to manage various sizes of loads, from as
few as two circuits up to 100+ circuits. While this traditional control
panel performs its function well, it is not smart.
control panels include an integrated time-clock that enables
programmable scheduling for automatic shut-off of selected loads, and
can provide monitoring and alarm features. Today’s intelligent lighting
control panel has grown to a sophisticated system that can automatically
switch lighting and other loads on and off from a time schedule, or in
response to an occupancy sensor or a building automation system. The
panels can also monitor the status of the branch circuit and various
inputs and can alert the facility manager of a tripped breaker, a faulty
sensor, or when the burn time of a lamp fixture exceeds a preset value.
These alarms are generated from an embedded email server that allows the
operator the ability to click on the email and go directly to the
panelboard and view the status from a standard Web browser.
Intelligent control panels are ideally suited to applications where the
granularity of control stops at the branch circuit level, such as retail
stores, warehouses, factories, transportation terminals and parking
garages are ideal applications. Advantages include scheduling for energy
savings, code compliance, and individual breaker control, which enables
branch circuits to be individually controlled or grouped together and
easy rescheduling and changing of control zones via a Web browser.
Control: Besides greater intelligence, other trends related to
control panels include distributed control and distributed intelligence.
control panel is centrally located in the electrical room, and houses
multiple relays or contactors for economical control of larger numbers
of loads. For example, to automatically switch the lights on and off on
entire floors of a building based on a schedule, a centralized control
scheme can be economical.
A new approach is
distributed control, which can be more economical in applications that
require more granularity of control zones. A distributed control system
uses smaller panels with 2-4 outputs each, which are located closer to
the loads they control, typically above the ceiling or in a closet. The
local controls are wired back to the nearby distributed panel rather
than all the way back to the electrical room, which can reduce wiring
costs. For example, if each floor in a building contains multiple rooms
that must be switched separately with different controls that must be
wired back to a control panel, then a distributed control scheme can be
more economical because the wiring between the control and the panel is
A distributed control
scheme, in fact, can eliminate the central control panel. For
scheduling, the distributed panels can be run back to a central
Intelligence: Another trend is distributed intelligence, a
subset of distributed controls. In a typical control panel, a processor
provides the intelligence. If the processor fails, the control system
fails because the intelligence is centralized.
In a distributed
intelligence system, a processor is located in each connected control
device, which increases reliability because if a processor fails, only
that device fails instead of the entire control system. This scheme also
allows control devices to be networked in virtually configuration.