The newest techniques and performance innovations can help maximize your lighting systems and reduce energy consumption.
About a year ago, Joseph Good III, President of the Illuminating Engineering Society of North America (IESNA), offered his view of what lighting would be like in the next two decades. He foresaw lighting systems that could adapt easily to changing needs of the user and function as a fully integrated system, rather than a collection of independent components.
These predictions are already coming true with today's exciting lighting technologies. Let's look at some of these technologies, which involve solid-state electronics, optical systems, and communications/control.
Making use of ballast factor. The wide-scale adoption of T8 linear fluorescent lamps and electronic ballasts is an ongoing phenomenon. Using solid-state components, electronic ballasts rectify the 60 Hz input and then invert it to create the 20,000 Hz to 60,000 Hz current, which operates the lamp. The higher frequency current of the arc stream causes greater phosphor excitement, providing more light output for a given ballast input power.
One of the biggest advantages of using electronic ballasts is the ability to consider the ballast factor (BF) in a design or specification. Though we weren't using the concept of the BF metric in the old electromagnetic ballasts era, we are today. Essentially, the BF is the ratio of light output from a commercial ballast compared to that obtained by a reference ballast, which has a BF of 1.
Thus, designers specify a BF of 0.88 to provide an equivalent light output when doing a one-to-one upgrade from T12 to T 8 lamps (that is, retaining the same number of lamps and fixtures).
At the same time, designers specify a BF of up to 1.2 for systems that produce too little light or in applications where they will reduce the number of lamps in a layout of linear fluorescent fixtures. So, in this case, the higher BF allows the lamps to provide up to 30% more light. This is similar to installing a four-barrel carburetor on a gasoline engine to deliver more power than a two-barrel design. It is possible to use up to a 1.2 BF without worrying about overdriving the lamps.
Asking HID lamps to move over. The enhanced performance of the T8 lamp/electronic ballast system makes it a viable alternative to a high-intensity discharge (HID) system. Generally, we use HID luminaires in tall warehouse spaces because of their good optical control and the high lumens they deliver in a single fixture. But compared to metal-halide (M-H) lamps, T8 fluorescent lamps last longer, are less glaring in open luminaires, feature better maintained lumens per watt, offer better color rendering, produce less glare, and allow you to switch them off and on in quick response to occupancy.
One warehouse in the Northeast opted to test T8 fluorescent lamps as an energy-effective alternative to M-H lamps. In narrow aisle areas, designers spaced white parabolic direct/indirect 8-ft-long industrial luminaires 16 ft on center, providing average maintained 5 vertical footcandles (fc) with a maximum ratio of 12 to 1. An instant-start electronic ballast serves four F32T8XL/835 lamps in each fixture. Passive infrared occupancy sensors switch off 80% of the luminaires in an aisle when the area is inactive.
In bulk storage and shipping, the designers mounted 12-ft-long, nine-lamp fluorescent luminaires on 26-ft217-ft centers to provide 20 fc horizontal of ambient lighting. The premium for this solution was $70,000, but the simple payback for the design is only 2.1 years at .068 cents/kWh during peak hours.
Because this project was part of the Rensselaer Polytechnic Institute, Troy, N.Y., Lighting Research Center's DELTA program (Demonstration and Evaluation of Lighting Technologies and Applications), the organization had the opportunity to evaluate the installation -- in terms of equipment and user response, which was positive.
HID lamps hold their own in upgrades. HID lamps still retain their high-performance reputation. Specifically, many customers now use the new pulse-start (PS) family of M-H lamps to upgrade recently installed standard M-H systems, which replaced outmoded high-pressure sodium lamp systems.
Available in ratings from 35W to 700W, the PS type lamps do not require a starter electrode in the arc tube, as required in standard pinched arc tubes. These lamps also boost lamp efficiency up to 110 LPW, improve lamp maintenance up to 80%, provide consistent lamp to lamp color, and allow 50% faster warm-up and restrike.
The higher mean lumens of a 360W PS lamp (31,500 lumens) outperforms the lower mean lumens of the 400W standard lamp (28,800 lumens). If a warehouse lighting layout requires 400 fixtures with the 400W standard M-H lamp/ballast system, you'll need only 366 fixtures if you use the new 360W PS lamp/ballast system.
Optical waveguides enhance visual comfort. Many in the industry now use semi-refractive prismatic film in pendant-mounted fluorescent lighting fixtures. This optical lighting film delivers light from a linear light source along the length of the film; the film also allows the light to escape in a controlled manner to provide uniform and consistent illumination throughout a plane.
For more than 20 years, the goal of office lighting has been to eliminate direct light source glare and prevent the creation of veiling reflections on a cathode ray tube (CRT) monitor. Because the position of the slightly convex CRT screen is almost vertical, it picks up reflected glare from fixtures positioned behind the worker. For that reason, designers now use fluorescent luminaires, with deep louvers to shield the lamps, or pendant-mounted indirect luminaires.
However, the next generation of personal computers uses liquid crystal display (LCD) flat screen monitors. The flat panel screen generally tilts backward 15 degrees to 30 degrees from vertical and is usually below eye level. Today's louvered fluorescent fixtures, with their highest candlepower, direct downward; creating unwanted glare for someone viewing an inclined flat screen monitor.
As Willard L. Warren, FIES, describes in Lighting Design and Application magazine, a new fixture design solves the problem by carefully controlling the direct downward component of light. With its shallow cross section, the fixture uses a pair of 54W T5 HO fluorescent lamps to project light through both sides of an acrylic panel.
A semi-refractive film on the bottom side of the panel delivers a uniform, low-glare pattern of light downward. Thus, 24% of lamp lumens is downward and the remainder is upward. By balancing the brightness of the panels with the ceiling brightness, the luminaire avoids distracting reflections or shadows on the LCD flat-panel screen.
Fiber optic lighting broadens its scope. Let's look at another light "waveguide" technology. Although the entire fiber optic market is only a fraction of 1% of the lighting industry, it continues to be a technology that captures the attention of attendees at the annual LightFair conference. Specifically, fiber optic systems are advantageous in places where you have impediments to using normal fixtures, such as locations where access is difficult or liability is a problem.
We see the most exciting new developments or improvements with the illuminators, including new reflector technology and lenses for end-emitting fibers.
But lighting designers and contractors also agree it's difficult to look at a catalog and try to figure out what's going to come out the opposite end of the illuminator when installers assemble a kit of parts.
Controlling lighting. The use of automated lighting control such as timers, occupancy sensors, and photo sensors are fairly common in modern buildings. Specifiers now use a variety of building control/automation systems (especially direct digital control or DDC) to activate lighting circuits and contactors.
Many manufacturers of lighting systems are working on gateways that allow limited interoperability between their proprietary systems and open protocol DDC networks.
Low-voltage twisted pair wiring is the most common DDC networking medium, but depending on bandwidth needs, proximity, and other factors, many other media are in the specification process. These include narrow band or spread spectrum power line carrier (PLC) signaling, radio frequency (RF) transmitters and infrared (IR) transmitters. Routers are available to extend a direct digital control network over standard or dedicated phone lines via modem or over a transfer control protocol/Internet protocol (TCP/IP) network such as a corporate Intranet or the global Internet.
The Internet protocol is emerging as the most important way of controlling lighting or any electrical load from just about anywhere.
Lighting control using Internet and pager technology. A new technology, pager lighting control, is an alternative to time clocks and photocells. A pager control system has three elements: a remote receiver box mounted at the lights you want to control. called the Remote Communications Unit (RCU); a ground-based computer that broadcasts instructions to the receivers; and a satellite pager network to complete the connection.
The RCU contains a processor to control the lights, a built-in clock with battery backup and a pager receiver that gets information from the satellite network four times per day. Each transmission burst includes the exact time (to calibrate the remote unit's clock), the day's sunset and sunrise times, and any received modifications to the local programming instruction. Thus, the RCU can turn lights off or on at any time of day or at any time relative to sunset or sunrise. For example, the controller can turn a parking lot's lights on at 25 min before sunset and off at 2 a.m.
Developed for billboard illumination, the system ideally eliminates the thousands of dollars wasted on illumination for outdoor advertisement. Billboard lighting continues to be the largest market for pager controllers, but other applications include street lighting, parking lot lighting, architectural floodlights, illuminated signs, and outdoor lights for municipal facilities. Controllers can maintain indoor lighting for gyms or similar facilities.
Facility managers want accurate on/off times for important lighting loads, since unnecessary usage reduces profits. A shopping center in North Carolina uses the pager control for parking area lighting, wall- and roof-mounted floodlights, pedestrian walkways, and tenant display signage. At times, tenants extend operating hours, and controllers can remotely make this change in schedule. Thus, a pager control system is a relatively inexpensive solution for lighting control, and it offers enhanced features.
In the past, you had to call the manufacturer's toll-free telephone number to request a change in schedule. Now, accessing the manufacturer's Web site can make an initial control setup or change in a schedule. Click on "Unit Programming." This takes you to the programming page to request a name and password. Then set up a timing schedule for any electrical load at any remote site.
How about if a billboard (or other electrical load) was able to send a message saying, "one of my light bulbs has burned out?" One system, which consists of a two-way wireless communications device and an RCU, can do just that. The system enables operators at the central operations facility to control and monitor lighting schedules and other devices from their computers. The unit immediately diagnoses when an out-of-limits failure occurs, what the problem is, and sends the information back to an operation center. A two-way wireless communication device relays all information to and from the RCU. E-mail, pager, and/or fax then notify the user. Information reported includes loss of AC power, resumption of AC power, and lamp failures.
By becoming familiar with the latest lighting technologies, you can add them to the range of solutions applicable to an illumination project. The results can be success stories, such as: an energy-saving warehouse design of your own; an aesthetically pleasing lighting environment for a computer-intensive workspace; a conference center or research facility; or a lighting scheme that blends architectural and theater lighting techniques.