Upgrading the lighting in manufacturing facilities with advanced energy-efficient systems can slash energy costs while boosting employee productivity and morale.
Lighting generally represents about a third of a facility’s energy costs. The payback for a lighting retrofit, in many instances, is fewer than two years, with manufacturers and employees continuing to reap the advantages associated with elevated light levels for many years.
Cost vs. Savings
Most industrial manufacturing facilities are older and cannot afford or justify the expense of constructing a new facility. Companies, however, often are able to invest in a lighting upgrade when the savings more than justify the cost of the initial investment.
Manufacturing facilities typically present many unique challenges that impact the type of lighting system required to provide the desired results. Many of these older facilities are constructed with high ceilings that appear dark and cavernous and can create the perception the facility is gloomy and insufficiently illuminated.
These facilities often include many physical impediments—overhead pipes, wire ways, cranes, and conveyor systems—that cast shadows and dictate fixture placement. Large pieces of machinery can block or consume light, and excessive heat and dirt will damage lighting fixtures and deteriorate the illumination.
Employers plagued with these situations often experience a sharp decline in employee performance and morale. Productivity decreases and defects and costly reworks rise because workers lack the light they need to efficiently perform their jobs. Safety—especially trips and falls—often becomes a problem because employees cannot see obstacles and other hazards. Workers’ concern about safety and their ability to perform their jobs may ultimately lead to greater employee turnover.
Conversely, higher light levels increase workers’ ability to discern detail, improve their depth perception, and enhance their ability to read critical gauges and meters. With a quality lighting system, the color rendering index (CRI) can be improved to enhance workers’ ability to identify true colors, which is important in facilities that manufacture electronic products and appliances with color-coded wires.
In many instances, workers are more productive even with lower illumination levels. They perceive the white light provided by modern sources as providing more illumination than the yellow light associated with high-pressure sodium sources.
While facilities will differ in their lighting requirements, designers should consider several elements when planning a lighting retrofit:
Ambient Temperature Heat is a tremendous challenge in many manufacturing facilities and not only degrades the light but can negatively impact the fixtures’ electronic components. Designers should always specify luminaires with a third-party listing agency designation, such as Underwriters Laboratories (UL), to insure that it is suitable for the ambient temperature that it will be subjected to.
UL classifications for light fixtures are typically 25 C (77 F), 40 C (104 F), 55 C, (131 F), and 65 C (149 F). Light fixtures should always have a higher rating than the ambient temperatures at the location that the lighting fixture is mounted. Ambient temperatures at mounting heights often substantially exceed those at floor level.
If, for example, the ambient temperature is 35 C in the area where fixtures will be installed, the luminaires should have 40 C rating. An installation with a 59 C ambient temperature should install 65 C rated fixtures.
A 65 C ambient rating is the highest fixture rating available. If the ambient temperature exceeds 65 C, fixture ballasts should be remotely mounted in an area with a lower ambient temperature.
Foundries are an excellent example of an application that will require 55 C or 65 C UL rated luminaires. A quality high-intensity discharge (HID) system with core and coil ballasts can operate efficiently at these higher temperatures when designed with adequate measures to dissipate heat. Most electronic HID ballasts are also able to tackle 55 C environments provided the fixtures include adequate heat sinks and conductivity to ensure the fixture keeps the internal temperatures (“case temperatures”) of the ballasts below their maximum operating limit as indicated by the ballast manufacturer.
The electronic ballasts in fluorescent systems have similar construction, but T5 and T8 lamps are not designed to operate in extremely hot or cold environments. Lumen output is usually substantially diminished within industrial environments where elevated heat is of concern.
For example, a heavy equipment manufacturer wanted to boost light levels to 60 footcandles in an area of the plant that was previously lit with a combination of aged high-pressure sodium fixtures, T12 fluorescent luminaires, and mercury vapor units. The manufacturer considered a fluorescent system but opted for a high bay HID system with electronic ballast because fluorescent luminaires are highly sensitive to heat.
The HID system installed, which uses 315-W ceramic metal halide lamps, has a UL/CUL 55 C ambient listing and can withstand the facility’s excessive heat, which is even worse during the summer. The manufacturing facility also benefitted from the luminaires’ extended 5- year warranty.
Lighting fixtures are available that are marine and IP66 rated to protect against the harsh elements found in hazardous environments and facilities such as food processing plants where hose downs occur daily.
Original Illumination Levels Unless the plant has been remodeled or is currently being used for a different purpose, the original lighting was probably designed to facilitate the tasks performed. The lighting installed during the retrofit, therefore, should be designed to the original illumination levels—unless the tasks performed have changed considerably.
Too often, lamps deteriorate over time and the specifier or engineer designs the retrofit application for the existing illumination level rather than the original level. A plant, for example, may have been designed for 30 footcandles when it was constructed. Over the years, light levels gradually declined to 15 footcandles without anyone really noticing.
The specifier or engineer who observes employees working in areas with diminished light levels may not realize footcandle levels were once higher. He or she may question workers, who report the lighting seems adequate. The specifier then designs for existing light levels, and the facility and its employees fail to reap the benefits associated with higher illumination levels.
If the facility is aged and no record exists indicating the original illumination levels, the plant may want to refer to recommendations provided by the Illuminating Engineering Society of North America (IESNA) and other industry groups, which will provide guidelines for the various areas within the plant, including assembly, hose-down operations, part stamping, warehousing, etc. Some companies also have their own guidelines, especially if the company operates multiple facilities.
Latest Lighting Technology Lighting technology has advanced tremendously during the past 5 to 10 years to provide high-quality, efficient illumination with more lumens per watt. T5HO has thrust fluorescent technology into light industrial facilities throughout the country due to smaller size and ability to fit multiple lamps and ballasts into one fixture at very reasonable prices. Technology such as ceramic metal halide lamps and electronic ballasts can also significantly reduce energy consumption while lowering operating costs.
Ceramic metal halide lamps—which are appropriate for many industrial applications as they are able to operate in very hot or cold environments —provide up to 120 lumens per watt, with .90 lamp lumen depreciation as compared to .70 or lower lamp lumen depreciation for previous probe or pulse metal halide lamps. Ceramic metal halide lamps are not only more affordable over the long term, but they provide color quality from the time they are installed, with a 90+ color rendering index (CRI).
The lamps offer the greatest potential for energy savings when used with electronic ballasts, which are directly interchangeable with magnetic ballasts. Electronic ballasts are typically more than 93% efficient and allow continuous dimming to 50% power, which is important in areas that are not constantly occupied.
Electronic ballasts also offer quieter operation and less lamp flicker, which is especially distracting in manufacturing environments. Maintenance costs are lower because only one lamp and ballast are required per fixture versus six lamps and two ballasts per fixture as required with many fluorescent high bay systems.
State-of-the-art optical systems help modern luminaires meet many of the specific needs inherent to manufacturing facilities, including equipment that creates shadows and obstacles that limit fixture placement. Luminaires with prismatic glass reflectors and refractors often represent a highly efficient and effective option for industrial applications because they are transparent and absorb minimal light energy.
A typical glass reflector or refractor assembly can provide as high as 95% efficiency. Quality reflectors or refractors also offer tremendous flexibility by controlling the light so it can be aimed directly at the task at hand, reducing the number of fixtures and energy consumed. Glass reflectors and refractors offer a number of economic and performance advantages including longevity, chemical and temperature resistance, and thermal shock protection. Glass also resists dirt accumulation because it does not build a static charge as does plastic or aluminum.
The most exciting technology advancement in the lighting industry is LED. The efficacy of this source is improving steadily and the cost per lumen is continuing to decrease with each release. Several manufacturers have already released high bay and low bay products or are poised to do so within the coming months.
Although LED is appropriate within the industrial space, it is vital that each fixture is tested to make sure that it is properly designed to meet the demanding requirements of many industrial environments. As stated with all sources previously mentioned, it is important to review each application individually to determine if it is appropriate for a given source. LEDs, for example, are extremely sensitive to heat. The hotter they run, the greater the negative impact on both their lumen output and their life. As other conventional light sources, it is important that the end user / specifier be aware of the UL Ambient Listing for a given LED product. If L70 life is obtained at a 25 C ambient, what is the L70 life of the same product at 55 C? Is the product even UL rated to operate within 55 C or 65 C ambient temperatures?
It is important that end users or specifiers ask many questions of the manufacturers to better understand the best opportunities for these new LED fixtures and to also understand their limitations so that their adoption is a positive experience for all.
Occupancy Sensors Dimming lighting fixtures during periods of inactivity may significantly reduce energy consumption. In the past, bi-level occupancy sensors provided limited choices: either operate the fixtures at 100% or dim them to 50%. Today’s technology allows fixtures to be continuously dimmed to any light level with the transition smooth and virtually unnoticeable.
Occupancy sensors and photocells for daylight harvesting offer the most effective options for any industrial space not occupied 24/7. An occupancy sensor detects activity within a space—such as an employee entering with a forklift—and turns the luminaires on. It also reduces energy consumption by turning the fixtures off after the last occupant leaves the area.
Occupancy sensors may be employed to control the lighting in large areas—such as warehousing and production spaces—and for task lighting in assembly areas, storage closets, employee washrooms, and other areas that are occupied intermittently.
Photocells have the potential to reduce daytime energy consumption by monitoring light levels and turning off fixtures when illumination from sources such as windows and skylights boosts natural light levels to a specific point. The photocells re-ignite fixtures when the light declines to designated levels.
Lighting systems that incorporate occupancy sensors or photocells typically include a manual override so light fixtures can be turned on or off as needed.
Outdoor Lighting Almost every industrial facility has some type of outdoor lighting—whether loading docks, roadways, parking lots, or walkways. Updating outdoor systems with new lighting technology and incorporating features such as photocells can improve visibility and safety while reducing energy and maintenance costs long-term. For example, a large semiconductor manufacturer recently replaced 310 high-efficiency 400-W high-pressure sodium luminaires in its 4,800-space parking lot because safety and worker perception were at stake as lamps burned out and ballasts failed. The manufacturer leveraged new LED lighting technology to reduce energy consumption by over 70% by installing 150 watt LED luminaires with sealed glass optics and an optimized thermal management system designed for 80,000 hours of virtually maintenance-free operation.
Luminaires were installed on existing poles to provide 1 footcandle of illumination, creating a crisp, clear environment for employees entering and leaving the parking lot at all hours. The company anticipates decades of maintenance-free operation.
Most industrial lighting projects are implemented in existing facilities seeking a complete redesign, one-for-one replacements, or a retrofit of the present system. While reduced energy consumption is the incentive for most lighting system upgrades, companies typically reap any number of quantifiable benefits, from increased light levels and improved productivity to fewer product defects and better employee morale.
Lighting technology has advanced tremendously during the past decade, ensuring greater efficiency with minimal maintenance. As a result, the payback for a retrofit lighting project is generally a matter of months—with companies enjoying the cost and performance benefits for many years.
Article republished with permission from Plant Engineering Magazine. For more information visit PlantEngineering.com