Page 43 - Energize June 2021

TECHNICAL

Luminaire lighting level control:

the future of efficient lighting

Energize staffwriter

he increased availability and usage light levels to suit the person occupying the workspace.
of LED light sources make it easier LLLCs, are a type of networked lighting control system with integrated sensors and
Tto control lighting than ever before. controllers in each luminaire, that are wirelessly networked, enabling the luminaires within the
Control strategies which used to be time system to communicate with each other and exchange data with a central control unit. The n
consuming and cumbersome can now be controller includes sensors for occupancy and daylight harvesting, with some also including
implemented effectively and inexpensively. air temperature sensors. Each fixture can independently modulate light intensity and apparent
In real applications, such as commercial colour, and sometimes even spectral distribution. This allows individual control of light levels,
buildings and public facilities, lighting is based on the individual requirements of the workstation.
dynamic because people move randomly, The luminaires can be controlled individually, for individual workstations, or grouped and
and optimisation models have become regrouped as needed for meeting areas, team zones, walkways, or aisles. LLLC systems
sophisticated and time-consuming, and are finding application in commercial buildings, schools and hospitals as well as industrial
require high-performance hardware. buildings such as warehouses. The system is highly flexible and can be reconfigured digitally
Current lighting control systems offer a without any adaption of wiring or luminaire controls.
wide array of controls, but most operate on Studies on existing systems show a considerable energy saving, which offsets the slightly
a zone basis, applying the same controls to higher cost. LLLC is generally seen as a tool for energy efficiency and cost savings, which
all luminaires within a zone. This is wasteful vary by facility type and hours of operation but are significant.
of energy in the modern open plan, flexibly LLLC luminaires consist of the light unit, dimmer control, daylight sensor, occupancy
allocated workspace office. A system, sensor, radio interface and main controller. Some advanced units may incorporate
called luminaire level lighting controls temperature sensors.
(LLLC) that allows individual control of The LLLC is controlled by both occupancy and daylight level. Figure 2(a) shows a
each luminaire, using distributed sensors room with all lights turned off. Figure 2(b) shows workspaces becoming occupied and the
embedded into novel lighting systems, not applicable space receives the required illumination, with the other luminaires being turned on
only saves energy, but allows adaption of at a predetermined dimmed level. Figure 2(c) shows how leaving a workspace results in level

Figure 1: LLLC sensor packages (Philips, Legrande)

(a) (b) (c)
Figure 2: LLLC in operation (Philips)

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