Reducing Energy Costs Through Innovative Lighting Control Technology
Modern office buildings are becoming more intelligent by necessity. The developing shortage of power generating capacity and the rapid rise in energy costs demand that lighting, the number one source of energy consumption in commercial offices, be handled in new ways that optimize energy efficiency.
In fact, ASHRAE/IES 90.1-1999 will become the standard energy code for all new construction within the next two years. This standard calls for reducing lighting energy consumption in buildings from 50% of the overall electrical energy used to 30% through the use of automated lighting control systems.
In the past, the benefits of energy-efficient lighting on the corporate bottom line came, for the most part, from investments in hardware, such as energy-efficient lamps and ballasts. With today’s modern fluorescent energy management systems, enhanced energy conservation capabilities start by picking up where these hardware-based technologies leave off.
“Daylight Harvesting” – Supplying The Missing Link Between Daylight and Efficient Indoor Lighting Control
The key to modern fluorescent energy management systems is a fully automated lighting control system that factors in available free natural daylight with the precise control of fluorescent lighting levels to maintain a pre-selected level of illumination. This technique is known as “daylight harvesting.” It delivers greater energy cost reductions than “dimming only” systems.
Daylight harvesting systems use strategically located photocells to measure the changing contribution of free natural daylight to a desired user-programmed level of light in a room. Then, they automatically dim or brighten the fluorescent lighting they control, adding only as much artificial light as needed to precisely maintain that programmed level. The result is a seamless blending of light sources that goes virtually unnoticed by the room’s occupants as well as a reduction in lighting energy consumption by as much as 60%.
Fluorescent Light Controller adjusts output in response to photocell readings of natural daylight. (view diagram)
A Modular Energy-Efficient Lighting Control System Built To Meet Ever Changing Needs
These highly efficient hybrid lighting control systems also combine the technology of “daylight harvesting “ with a host of innovative energy-efficient modular lighting controls, including dimmers, timers, occupancy sensors and photo-sensors that dim or turn off fluorescent lighting when a space is not being used. They incorporate the ability to interface with occupancy sensors to provide even greater energy savings. When single or multiple occupancy sensors are installed, programmed interior lighting is automatically turned OFF when the room is vacant and back ON to the programmed level when occupancy is detected. The use of movement sensors means energy savings up to a proven 50%.
Earlier systems of this type required direct programming of hard-to-access in-ceiling dimming power packs. Recently, though, new systems have offered easier programming through companion Wall Controllers or from a PC, using administrator software.
In general, the power packs have been programmed to follow a series of energy efficient protocols based on a least light law. By following the least light law, the power pack will adjust the light level to the least light called for by all of the inputs.
For example, if the power pack is turned on (either manually or by an occupancy sensor) and the Light Maintain Level calls for a lower output level than the last manual level, the lights will adjust to the lower Light Maintain Level. On the other hand, if the manual preset level is lower than the Light Maintain Level when the Power Pack is turned on, the lights will adjust to the manual preset level – because it’s the lowest level in this case. Of course, these systems allow users to manually override this level at any time. But, the least light law is applied at all times, except when overriding Emergency, Service Switch or Time Clock inputs are activated.
These systems can also be effectively tied into building emergency, load shedding and time clock systems. In the emergency mode, they switch lights to full brightness when the emergency system is activated. In load-shed mode, they can reduce light levels to a percentage of the current level selected to save energy during peak usage periods. The time clock function shuts lights OFF after the building is no longer occupied, offering up to 30% in energy savings.
Reducing Costs By Raising Worker Productivity Through Modern Lighting Controls
Beyond the contribution to corporate cost reductions realized by lowering the energy cost of energy-saving fluorescent lighting even further, these innovative lighting control systems add visual comfort to promote greater worker productivity. They allow workers to conveniently override automated settings manually to permit precise light levels matched to their individual needs. Convenient access is provided via wall-mounted and infrared remote controls or can be made available directly through individual PC workstations. Employees benefit from the right lighting for every situation and, in the process, provide productivity gains to the corporate bottom line.
Examples of Advanced Lighting Control Keyed To The Task At Hand
Optimum Lighting For Computer Workstation (view diagram)
A worker sets a low light “maintain level” around her workstation for greater visual comfort via Personal Dimmer software on her computer. Subsequently, the blinds are shut to reduce monitor glare from outside light. The Fluorescent Energy Management System responds automatically to the drop in natural daylight by compensating with an increase in the fluorescent lighting’s contribution to the previously selected level of overall illumination or “maintain level.”
Increased Lighting For General Office Tasks (view diagram)
Turning from the workstation’s monitor to more general office tasks, Centura is set to a full bright “maintain level” via the user’s Personal Dimmer software on a computer. The system automatically sets the fluorescent lighting’s contribution to 65% of the programmed overall illumination or “maintain level,” harvesting natural daylight to supply the remaining 35%.
Full Illumination Aids Night Crew Cleanup (view diagram)
The system is set to turn lights ON after normal working hours when occupancy sensors detect motion. The night crew can then easily locate and tap a Wall-Mount Dimming Controller for full brightness while cleaning. Lights shut off automatically when they leave. Lights then follow the “least light law” and turn on at the previously programmed lower maintain level when daytime employees return.
With the human resource costs far outweighing all other costs combined in a company, even a modest improvement in worker productivity and staff retention will easily offset the costs of an advanced lighting control management system.
By combining daylight harvesting and individual manual control, systems such as Leviton’s Centura Fluorescent Energy Management System can significantly improve worker productivity while generating considerable energy-savings that go right to the corporate bottom line.
