The following recommendations outline the most common ways to effectively save energy within various lighting systems. Some of these suggestions involve replacing the current lighting system with the most energy efficient bulbs, and installing occupancy sensors in low traffic areas to reduce lighting run-time.
Replace metal halide lamps with LEDs
Metal Halide lamps were once very popular for industrial lighting and are still used today. However, better quality light, especially over the life of the bulb, can be obtained with significant energy savings using LED sources. LED technology has advanced rapidly since 2010 and now offer cost effective solutions with better illumination characteristics. Many new fixtures are commercially available, but direct substitutions for existing HID fixtures are also available for a quick, inexpensive retrofit. Most often, these replacements offer service life two to four times that of metal halide lamps, with a higher coloring index and increased lumen maintenance. Normal simple payback periods for this recommendation range from two to four years, with shorter paybacks for installations where lights are on for extended periods of time (24x7).
Replace fluorescent tubes with LEDs
LED tachnology has advanced rapidly and there are many options available for direct retrofit of T8 and T5 fluorescent tubes. The LED sources provide similar lumen output and better light quality with lower power input. These drop-in replacements are pin and form factor compatible and so can be easily installed into existing fixtures. The range of options available include LED tubes that can work with exisiting "instant on" fluorescent ballasts, as well as self-ballasted tubes that can be used by disconnecting the existing ballast. LED power requirements can be 40% to 50% of the power required for fluorescent, and so paybacks for new projects can be just a few years.
Replace incandescent bulbs with compact fluorescent (CFL) bulbs
Incandescent light bulbs are usually found in offices, locker rooms, bathrooms, and other administrative areas. The main disadvantage of incandescent bulbs is that they only use approximately 10% of their energy to produce light; the rest is burned off as heat. By replacing incandescent bulbs with compact fluorescent bulbs, a reduction in initial lumens occurs. However, this loss in initial lumens is compensated by the CFLs' extended life, lower power consumption, and increased lumen maintenance (a decrease in the rate at which lamps lose their ability to produce light). Approximately 75% of the energy used by incandescent bulbs can be saved by switching to CFLs , and the relatively low implementation cost yields an attractive simple payback period for this replacement.
Install occupancy sensors
Occupancy sensors (also known as vacancy sensors) detect activity within a certain area and activate the lights as needed. Installing infrared or motion-detecting occupancy sensors will automatically extinguish the lights in unoccupied areas. These can be attached to a bank of lamps (limited by the wattage rating of the sensor switch) or on individual luminaires. Occupancy sensors should not be utilized with metal halide lamps due to the lamps' extended strike-up time, but are incredibly effective with fluorescent bulbs or LEDs. Offices, storerooms, and bathrooms are typical installation locations, but greater savings can be realized if they are installed in warehouses and tool cribs. Percentage energy savings will vary depending upon the amount of traffic in the considered area, but often lead to an attractive payback period of one year or less.
The following recommendations outline additional ways to save energy within various lighting systems. These recommendations are sometimes customary to specific facilities, but are still reliable sources for energy savings.
Install daylighting panels
Installing daylighting panels in appropriate locations is the best way to take advantage of natural daylighting. In areas where daylight provides sufficient lighting levels, skylights may be installed, making artificial lighting unnecessary. Daylighting panels do require constant upkeep in order to keep them clean and allow adequate lighting to pass through, and may result in significant maintenance fees. Furthermore, initial implementation of daylighting panels can also be costly, due to high labor costs and possible required shut-down time during installation. It is often most efficient to preserve existing daylighting panels rather than installing new panels, unless capital expenses are accessible. Daylighting panels may also be used in conjunction with photosensors, as explained below.
Install photosensors and take advantage of daylighting
Photosensors are control devices that adjust the lighting output of a system based on the amount of light available at a particular location. Some photosensors simply switch lights on and off, while others continuously control the lighting system's output. Photosensors installed in areas surrounded by natural daylight can adjust the output of the lighting system based on amount of surrounding light. Photosensors are relatively inexpensive to install, and can significantly reduce the amount of artificial light consumed during daylight hours.
Lower light fixtures in high ceiling areas
Typically, metal halide, mercury vapor, and high pressure sodium bulbs are used in high bay ceiling areas. Although these types of lamps have high luminous efficacy, they are inefficient industrial lighting sources. Much of the light produced is absorbed in the ceiling cavities instead of being directed into the work area. By lowering the ballast of the lights and replacing the bulbs with fluorescent lighting as described in some of the recommendations above, it is possible to achieve the same lighting levels while decreasing energy consumption. Approximately 20 percent of the energy consumed by the lighting system can be saved by lowering the light fixtures and replacing the bulbs with fluorescent lighting.
Install specular reflectors/delamping
Typically, most fluorescent lighting fixtures have specular reflectors which are reflective panels placed within the ballast chambers of a fixture that reflect light to surrounding areas. However, if they do not exist within the fixture, specular reflectors should be installed. The use of these reflectors reduces light loss and redirects light out of the fixture. The reflectors themselves do not save energy; however, installing them can increase lumen efficacy, which allows for delamping, or removing bulbs from fixtures. Generally, each specular reflective panel allows one bulb to be removed from a lighting fixture. The reduction in lighting levels by removing a bulb is compensated by the increase in lumens that the reflective panels provide. Therefore, there is no overall change in lumen levels. The reduction of bulbs in the existing fixture allows for electrical energy savings. Typically, 15 percent of the energy used by the lighting system can be saved by installing specular reflectors in panels that do not have them.
Turn off lights when not in use
Although it seems obvious, maintaining a regimented "lights-off" policy is perhaps the simplest way to reduce lighting consumption. Installing signs near light switches in storerooms or offices reminds employees to contribute to the overall energy savings.