Business in the U.S. has changed dramatically from the days of heavy industry when illuminating with high-pressure sodium systems was common. Those who specify and buy lighting systems for industry should be aware of the current trends in manufacturing.
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As the industrial sector continues its transition to a 21st century digital age, many issues affect production facilities and their lighting systems. An aging workforce, worker productivity, product quality and technological advancements, such as miniaturization, affect the way effective manufacturing facilities are lighted.
Providing an effective lighting design for a manufacturing facility is a challenging task. Industrial lighting systems should provide energy-effective illumination in quantities sufficient for doing productive work safely and with quality to enhance visibility and productivity in a pleasant workplace. The goal is a reliable and efficient system that is easy to maintain. The tangible benefits of reduced energy costs resulting from improved efficiency are easy to calculate but, for many companies, there need to be additional compelling reasons for investing in a new lighting system.
Poorly designed lighting systems, on the other hand, have been shown to reduce worker productivity, increase absenteeism and decrease safety. Downtime is sometimes used as an indicator of work quantity and errors; scrap or rework can be used as an indicator of work quality.
The soft benefits
Many facilities have engaged in the International Organization for Standards ISO 9000 certification, the most widely known and successful manufacturing quality standard. The program addresses lighting in the section that ties good lighting to high product quality.
Other benefits of well designed industrial lighting include reduced eye fatigue and headaches, which keeps workers alert and on the job. These lighting systems provide the right amount of light for the occupants to work productively.
Improved workplace appearance through better lighting can increase worker morale, improve the company image and reduce accidents. These intangible benefits are more difficult to measure, but they can far outweigh the other benefits.
The always demanding manufacturing processes require lighting systems to support a wide variety of visual tasks — from highly controlled, precision clean rooms to uncontrolled, less-than-sterile foundries. Many older industrial lighting systems are merely “laid out” to provide a certain light level on a horizontal work plane. Inadequate lighting often is the result of using only an overhead system to light many vertical tasks found in most manufacturing facilities.
Using lighting design software to render light patterns can help you model the lighting on vertical work surfaces. This approach represents a departure from the traditional method of simply looking up a recommended (horizontal) light level for a certain task in a particular industry. Because many tasks are common across industries, “The 9th Edition of the Illuminating Engineering Society of North America (IESNA) Handbook” changed directions and now concentrates on visual tasks and the quality requirements for each. Better industrial lighting should be the result.
Using high tech
An engineered approach to illuminating your manufacturing tasks starts with the task’s visual requirements and an ambient system that might be able to use daylight, high-intensity discharge (HID) or high-intensity fluorescent (HIF) systems supplemented with task lighting. Manufacturing tasks have changed, especially in their orientation. Many tasks must be viewed on the vertical plane, whereas traditional tasks were on the horizontal plane. This change in viewing orientation requires less straight-down light and more light on the vertical plane coming from different directions, including light reflected from the ceiling. Industrial lighting applications require designers to understand the tasks to be performed, which determines the right type of lighting.
The robots and automatic machines doing so many repetitive tasks in modern factories don’t need to see, but the maintenance personnel who care for them do. This represents an opportunity to control the lighting. For example, a low lighting level can be provided when the machines don’t need tending and a high level provided when machinery requires attention. In addition, automated machinery might be on tour stops, and warrant illumination so guests can observe the fascinating operations.
Most industrial tasks now require better color rendering than traditional tasks. This can easily be provided using lamps that have a higher color rendering index (CRI). Most new plant fluorescent lighting systems use lamps that are rated at 85 CRI. Another benefit of using higher CRI lamps is that they provide better contrast for black and white tasks.
To improve contrast, consider using task lighting from the proper direction to evaluate the visual results. The IESNA RP-7 (Recommended Practice for Industrial Lighting) shows how to light various piece parts and products and shows photos of these effects. Contrast can be further improved by using a contrasting colored background. The result is similar to the effect when white pearls are displayed against a black velvet background. The size and the shape of the pearls are easily seen and any surface blemishes are easily detected.
The quality angle
It can be challenging for an inspector to locate defects on product surfaces that are sometimes reflecting light back in their eyes. When task lighting flickers, inspectors have difficulty staying at their posts for a full shift, and workers can suffer from headaches, nausea and eyestrain. Inspectors who are sensitive to flicker can exhibit an increase in speed, but a decrease in accuracy of performance when exposed to low frequency (120 Hz) flicker. Light flicker has a greater impact on people who suffer from headaches, stress and visual discomfort. When inspectors need lighting with high light levels, use electronic ballasts to operate the fluorescent lamps. This ensures that the flicker associated with magnetic ballasts doesn’t interfere with inspection tasks.
Tasks in the warehouse require specific lighting considerations. Older warehouse designs concentrated light straight down from the fixtures centered in the aisles so that there was sufficient illuminance (footcandles) at the floor. But, warehouses have changed from floor storage facilities to more compact, racked storage. The fronts of the stacks and shelving now need to be lighted so labels can be seen. This requires attention to lighting the vertical plane and to provide adequate light at the bottom shelf. The focus of warehouse design is now on vertical light distribution, which can best be done with lighting design programs either by the designer or the fixture manufacturer.
Make a difference
Improvements in lighting systems are just one way plant professionals can support demanding manufacturing processes. Older lighting systems aren’t able to provide the quantity or quality of light required for the tasks in modern production facilities and should be evaluated for replacement (re-lighting) or retrofit.
At the same time, there’s pressure to control operating expenses by managing the energy used by facility systems. Installing more efficient lighting can reduce electric cost. Of all the ways to save energy in a plant, lighting is the simplest and most risk-free. However, from an energy management perspective, manufacturing facilities are often overlooked as candidates for retrofit or re-lighting because lighting represents only about 5% to 10% of the energy bill.
Industrial process heating and cooling and machine drive loads, on the other hand, consume a much larger percentage of electrical energy than in commercial buildings. Warehouses are an exception, where lighting systems consume a higher percentage of the total energy absent freezer storage and air-conditioning.
The ASHRAE/IESNA 90.1 Energy Code sets lighting power density (LPD, measured in Watts per square foot) values with input from the IESNA application committees, including the Industrial Lighting Committee. Using state-of-the-art lighting equipment, new and re-lighting designs can easily meet the new, lower LPD requirements.
Moving forward
This is a good time to plan strategic investments in industrial lighting systems. Facilities have until December 31, 2008 to plan and install energy-efficient lighting systems to reap the benefits of the commercial building tax deduction provision of the Energy Policy Act of 2005 (EPAct05). While savings from monthly electric bills and the tax deduction will pay for these improvements, the intangible benefit of improved worker productivity may trump them all. Sound engineering is required to achieve the 40% reduction necessary to qualify for the $0.60/sq. ft. tax deduction. Commonly available products and well-established strategies are used to meet the requirements.
Existing lighting systems that already have quality fixtures can be retrofitted with standard or high-lumen Super T8 lamps. Using fewer high-lumen lamps and wisely choosing ballasts can provide the most cost-effective results. Select ballasts based on their ballast factor (BF) to provide the required light output.
A new generation of so-called extra-efficient ballasts consume 3 W to 6 W less than generic electronic ballasts (GEB), but provide the same amount of light. The major ballast companies now have these in their catalogs and on their Web sites. While the high-tech ballasts cost from $1 to $4 more than a standard unit, they can save from $20 to $40 in electrical cost over the 60,000-hour life of the ballast.
Bilevel switching is required for projects to qualify for the tax break. Occupancy sensor applications should use programmed-start ballasts to extend lamp life. You can meet the bilevel switching requirement when only one wall switch (or relay contact) is available to control three or four lamp fixtures by using a bilevel ballast. This eliminates the costly wiring required to rezone or add switches (or relays). When the switch is first thrown, the lamps light up like normal. Quickly flipping the switch (or relay) off and back on switches the system to the lower light setting.
Storage and warehouse spaces are ideal candidates for upgrades to high-bay lighting fixtures, but such spaces require a 50% reduction —— to 0.6 W/sq. ft. — to qualify for the $0.60/sq. ft. deduction.
Achieving this objective by replacing existing HID lighting systems with high-bay fluorescent systems requires a thorough analysis, but these systems are easy to dual-switch, because the high-intensity fluorescent fixtures have multiple ballasts. Sensors mounted on the fixtures can be used to meet the bilevel requirement.
For example, 400-watt standard metal halide systems mounted on 20-ft. centers can be replaced with either six-lamp T8 fixtures (0.56 W/sq. ft.) or four-lamp T5HO fixtures (0.59 W/sq. ft.). Either solution would qualify for the tax deduction. For 400-W standard metal halide systems mounted on shorter centers, a new layout or a mix of four and six lamp fixtures is needed to meet the requirement.
An alternative to HIF solutions is to retrofit or replace the existing HID systems with pulse-start (PS) systems. For example, 400-W metal halide fixtures can be retrofit or replaced with 320-W pulse-start retrofit kits or new fixtures. Recent developments in electronic ballasts for higher-wattage metal halide lamps make PS even more attractive.
Some manufacturing and warehouses are improving their lighting by returning to skylights — long abandoned by many because of roof problems. New, prismatic skylights provide diffuse daylight with a high CRI, don’t leak like the old ones did — and the electric lighting can be shut off or dimmed to achieve substantial savings.
Lighting systems are tools that can make or break a plant’s productivity, depending on how well they perform. Quality lighting systems improve worker’s vision for productive work and can provide significant energy and maintenance savings when effective equipment is chosen.
John Fetters, president of Effective Lighting Solutions, Inc., is revising “Applied Illumination Engineering” for Fairmont Press. Contact him at [email protected] and (614) 258-5483.