Lighting Efficiency

To save energy used in lighting, reduce the electricity consumed by lighting fixtures by:

• Reducing Lamp Wattage
• Improving Lighting Control Devices (Reduce On-Time)
• Performing Maintenance

Reduce Lamp Wattage

Replace standard incandescent lamps that are used for long periods at a time with compact fluorescent  lamps (CFL) for substantial energy savings. CFLs are the most significant lighting advance developed for homes in recent years, combining the efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures. CFLs can replace incandescents that are 3 to 4 times their wattage, saving up to 75% of the initial lighting energy. Although CFLs cost from 10 to 20 times more than comparable incandescent bulbs, they last up to 10 times as long). This energy savings and superior longevity make CFLs one of the best energy efficiency investments available.

Although most lights in commercial buildings are fluorescent, incandescent light bulbs serve about 20% of commercial lighted floor space and account for nearly 40% of commercial lighting energy use. Commercial fluorescents between 7 and 18 watts can be used to convert incandescents with 20 to 150 watts per fixture. Lights that operate much of the time, such as hallway or stairwell lamps, are popular applications for these lamps.

Light-Emitting Diode (LED) signs are an efficient alternative to incandescent lamps for illuminated exit signs because they use only about 5 watts and last 20 years. The life-cycle cost of LED signs is about one-half that of a compact fluorescent lamp and about one-quarter of the life-cycle cost of an incandescent lamp.

Replace 300-watt halogen torchieres with CFL torchieres. A 60-watt CFL torchiere will produce 25% more light at an operating temperature that is 500° F cooler than the halogen. The 40 million halogen torchieres used in the United States consume 20 billion kWh annually, 5 times the energy generated by wind turbines and photovoltaics, and they contribute to many fires, some of them fatal, because of their high temperatures.

T12 lamps are very inefficient and should be changed out for 32-watt T8 tubes and electronic ballasts as part of normal programmed maintenance. Subject to a thorough check of the optics and the area lighting design, the fittings may be better upgraded to accommodate a new ‘gear tray’ fitted with the slightly shorter T5 lamps plus electronic ballasts and new reflectors.

Improve Lighting Control Devices

Lighting controls are devices for turning lights on and off or for dimming them. Manual controls should be used in spaces that accommodate different tasks or that have access to daylight, and occupants should be encouraged to shut lights off when they aren't needed. Automatic controls such as occupancy sensors are convenient for turning lights off when areas are unoccupied. Autodimming controls automatically adjust light levels to existing daylight. Examples of lighting control devices include:

• Snap switches, located in numerous convenient areas, make it easier for people in large, shared spaces to turn off lights in unused areas.
• Photocells turn lights on and off in response to natural light levels. Photocells switch outdoor lights on at dusk and off at dawn, for example.
• Mechanical or electronic time clocks automatically turn on and off indoor or outdoor lights for security and safety.
• Spring-driven crank timers limit lights to short durations where the need for light is brief.
• Occupancy sensors activate lights when a person is in the area and then turn off the lights after the person has left. They also offer security advantages over continuous lightings. When lights suddenly come on, they startle intruders and alert residents and neighbors to motion in the area.
• Dimmers reduce the wattage and output of incandescent and fluorescent lamps. Dimmers also increase the service life of incandescent lamps significantly. However, dimming incandescent lamps reduces their light output more than their wattage, making incandescent lamps even less efficient as they are dimmed. Dimming fluorescents requires special dimming ballasts and lamp holders, but does not reduce their efficiency.

Perform Lighting Maintenance

Relamping is just one maintenance strategy managers can employ to ensure lighting-system efficiency. Regular maintenance is essential to ensure that facilities receive the desired quantity and quality of light, as well as energy efficiency, from their lighting systems. Periodic maintenance can produce a range of benefits, including a brighter and cleaner workplace, a higher level of security, and enhanced productivity.

Within system maintenance, maintenance and engineering managers have a number of strategies that can increase efficiency and savings when it comes to lighting system operation. These strategies fit into the following five categories:

• Relamping
• Keeping it Clean
• Targeting High Costs
• Maintenance Self-Check
• A Budget Caveat

Relamp

Scheduling regular lamp replacement has become a popular choice for managers seeking to maximize lighting system effectiveness and control lighting costs. Managers have several relamping strategies from which to choose. They can have workers replace lamps as they burn out, or they can schedule workers to replace all lamps in a small group of fixtures, such as those on one floor, at one time. Among the challenges for managers is to determine the relamping strategy that best fits their facilities’ needs.

Managers have several incentives to schedule lamp replacement. The main reason — one often overlooked by lamp manufacturers — is the high cost of lost worker productivity as lamp changers travel around a facility. Observations show that work often stops or slows down in the vicinity of a fixture as it is opened, burnouts removed and new lamps installed. Scheduled relamping offers several additional benefits, but the most important one relates to disruption. Managers should select those areas most vulnerable to disruption as first candidates when starting this practice.

Many managers use formulas to determine group relamping intervals, but lamp life values used in these formulas usually are incorrect, leading to wrong answers. Managers might consider an alternate method obtained from a maintenance supervisor who has been using it for years, a method that works better and offers a simple, elegant, self-regulating solution. Here’s how it works:

• Schedule relamping at 70 percent of rated lamp life, the point on the lamp mortality curve at which 10 percent of burnouts have occurred. 
• Purchase 10 percent more lamps than required for the group relamping. 
• Use the 10 percent overstock only to replace burnouts that occur in that group after the group relamping. 
• Relamp that group again when the 10 percent stock is depleted.

Keep it Clean

Many facilities pay little or no attention to the need to keep light-reflecting surfaces and lenses clean in order to maintain designed light levels. In fact, most maintenance budgets do not include funds to clean fixtures.

Traditionally, lighting systems are overdesigned to accommodate this expected lack of cleaning. A study of New York City offices performed by Penn State University, however, showed that if cleaning became a regular part of lighting maintenance, lighting systems could be downsized, saving more in energy costs than organizations spend on maintenance, even taking into account high-cost New York City labor.

A simple way for in-house staff to clean light fixtures is to wipe reflecting surfaces and lenses when changing tubes. In the past several years, smoking regulations and other pressures have produced cleaner office environments, so in most cases, cleaning when changing lamps is sufficient.

A soft cotton cloth works well, but the cleaner must constantly turn it to provide a clean surface, as each face quickly becomes dirty. If static electricity is a problem, the cleaner can add a small amount of anti-static solution to the rinse water. Laundry fabric softener also provides an inexpensive anti-static.

Parabolic fixtures and specular surfaces found on reflectors require special attention because they mar easily; fingerprints that mark these surfaces during installation or relamping usually cannot be removed. Wearing white cotton gloves helps protect these surfaces from fingerprints.

Fixtures that are not very dirty can be cleaned with a soft cotton cloth using glass cleaner, or the worker can use a mild detergent if glass cleaner does not do the job.

Organizations that outsource lighting maintenance can experience a range of improvements. For example, lighting management companies clean fixtures as they change lamps, something that can be difficult to accomplish with in-house staff.

The benefit cited most often is that outsourcing frees up in-house maintenance staff to concentrate on higher-priority tasks. Outsourcing also can eliminate accidents resulting from such activities as employees using lift equipment, and it can eliminate the need to purchase and store lamps and ballasts, as well as the cost of recycling pickups.

Responsible lamp disposal also is important. In-house maintenance staff shouldn’t throw away or crush spent lamps. Because lamps contain mercury or lead, recycling them is the best practice. See www.lamprecycle.org and the RCEA Fluorescent Take It Back page for more information on recycling services.

Target High Costs

Managers also can control lighting maintenance costs by identifying areas with particularly high costs. Tracking lamp usage can help locate such system problems as high voltage or vibration, either of which can shorten the life of incandescent or halogen bulbs.

Tracking also can identify poor lamp performance. For example, in systems with 12-volt MR-11 or MR-16 lamps, one permanent solution to extend lamp life is to install a small buck-boost transformer to lower the voltage to about 11.5 volts. Although this tactic slightly lowers light output, it also extends replacement intervals and reduces replacement costs, since workers will replace lamps less frequently.

Also, workers should take care not to touch the envelope of these bulbs or halogen bulbs because doing  so leaves skin oils on the glass surface. As these bulbs heat and cool, the oils cause uneven stress, leading to glass cracking and shorter lamp life.

Screw-base-type compact fluorescent lamps (CFL) offer the major advantage of long life – up to 10,000 hours — which reduces labor significantly. They require no external ballast and can be used in the same sockets as incandescent lamps.

These CFLs also offer considerable energy savings. Manufacturers recently introduced new, larger screw-base CFLs — 55, 65 and 85 W — to replace incandescent lamps of 200, 250 and 300 W, respectively.

For areas that need incandescent lighting, including halogen lamps, managers have options that can extend incandescent lamp life. They can either use 130-volt rated lamps, which are especially good for higher-than-normal voltage, or they can set a wall-box dimmer control in the electrical closet containing the feed for a group of incandescent fixtures.

In this case, the dimmer serves as a preset control — set off the high end — and is not normally used to dim the lighting. Should complaints arise after the bulbs have burned for some time and experienced lumen depreciation, the dimmer can be set higher.

Another example of high-cost lighting maintenance occurs in areas that still have very-high-output or power-groove fluorescent lighting. Usually installed in industrial facilities, these systems are notorious maintenance sinkholes and should be replaced with either a high-performance T8 or T5 fluorescent system or a pulse-start metal halide HID system.

Paybacks for this investment are significantly improved with documented maintenance labor savings, as well as energy savings. Maintenance and engineering managers have a number of reasonable options when it comes to improving lighting system maintenance and reducing labor costs. The challenge for maintenance and engineering managers is to find those opportunities that help achieve their organizations’ goals, as well as enhance workplace productivity.

Maintenance Self-Check

To determine a lighting system’s level of effectiveness, maintenance and engineering managers can use this lighting maintenance self-check:

• 1. Locate an area of 100 fixtures, preferably with the same number of lamps per fixture
• 2. Count the number of missing, burned out, or flickering lamps.
• 3. Divide this number by the number of lamps per fixture.
• 4. Count the number of fixtures with broken, discolored lenses or missing parts.
• 5. Count the number of dirty fixtures.

Add the values from steps 3, 4, and 5. Grade: 0-10, keep up the good work; 11-20, need to spend more time; more than 20, spend much more time or consider outsourcing.

A Budget Caveat

Mistakes often happen when preparing annual maintenance budgets related to lighting costs and needs. In some cases, in the year following a major upgrade or re-lighting project, managers don’t consider costs properly. Normally during this period, the quantities of replacement lamps and ballasts will be lower than expected because the products are new. As a result, expenditures for labor and materials tend to be unusually low. The common mistake is to base the following years’ budgets on this exceptional year. Instead, managers will get more accurate numbers by using expenditures for a three- or four-year period.