Shedding Light on Industrial Facilities
Designing a lighting system for industrial facilities has become a practice in using the right tools. Our panel of lighting designers discusses innovations and best practices as they tackle new fixtures, better controls, retrofits and energy efficiency in this month's M/E Roundtable.
Designing a lighting system for industrial facilities has become a practice in using the right tools. Our panel of lighting designers discusses innovations and best practices as they tackle new fixtures, better controls, retrofits and energy efficiency in this month’s M/E Roundtable.
Consulting-Specifying Engineer (CSE): What approaches to industrial and high-bay lighting are you using or have you explored? Do you have a standard that you use?
MCGONEGLE: We typically specify metal-halide, high-intensity-discharge [HID] sources in high-bay lighting applications, and linear-fluorescent-enclosed and gasketed-luminaires for industrial task lighting. High-pressure sodium [HPS] sources are used for better energy savings when color rendering is less critical. We have started to specify pulse-start metal-halide sources due to their better color uniformity, lumen maintenance and shorter restrike time.
We use the Illuminating Engineering Society of North America [IESNA] illuminance recommendations and field measurements of existing lighting levels in designs. Our lighting committee has developed a spreadsheet that calculates the maintained illuminance and the American Society of Heating, Refrigeration and Air-Conditioning Engineers [ASHRAE] 90.1 interior light power allowance, which gives designers a quick method of exploring alternatives.
BYRAIAH: We have used high-bay HPS vapor lamp fixtures in some of our industrial and manufacturing facilities. In some areas where color rendition is critical, we have designed the lighting using metal-halide lamp fixtures. The ceiling heights in these facilities are typically 20 feet to 35 feet, with the ceiling and walls typically painted white to increase the light reflectance.
FETTERS: The trend to white light solutions has pretty much dictated that either fluorescent or metal-halide sources be used for new or relighted industrial spaces. Recent evidence from vision research shows that people can do demanding visual tasks better using white light. We are currently reviewing case studies of manufacturing applications that have used fluorescent lamps in high-bay applications. There are some compelling reasons: higher lumen maintenance, instant-on operation and dimming or bank switching.
Generally, we prefer to use an engineering approach to lighting manufacturing tasks based on the visual requirements for the tasks. This results in a system that is supplemented with task lighting that takes into account the needs of each application.
This is a departure from the old method of simply looking up a recommended horizontal light level for a certain application in a particular industry. Since many visual tasks are similar between industries, the newly published IESNA Handbook concentrates on visual tasks and the quality requirements of each. I believe that this will result in better industrial lighting.
New design tools
CSE: Have there been any recent innovations in computer and software applications for industrial lighting design?
BYRAIAH: Recently, many lighting manufacturers have started providing lighting calculation software with photometric data at no cost to lighting designers. These tools will definitely help the designers to estimate the lighting level, model the areas of illumination very accurately and improve the design quality.
FETTERS: We have been using version 7.5 of LumenMicro because it allows us to do daylighting design as well. Daylighting is making a comeback and we need to be able to have tools to design for daylighting as well as for electric lighting.
MCGONEGLE: Software programs have simplified the calculation of vertical-task illuminance and allow quick comparisons of several luminaires. Programs with daylight calculations allow the designer to do an economic justification for daylight harvesting using high/low or dimming controls. In addition, programs with rendering capabilities can show the visual effect of uplighting, which is not apparent in numeric printouts.
CSE: What other, if any, significant innovations have there been in lighting products and systems?
FETTERS: The most exciting lighting product innovation that we have seen is the high-wattage pulse-start metal-halide system. The new pulse-start system design has eliminated the old system compromises made to accommodate the probe starting method.
BYRAIAH: There have been several innovations in HID lamp and ballast technology. Metal-halide pulse-start lamps improved the light output, color stability and restrike time significantly. Bi- and tri-level lamp ballasts in metal-halide and HPS lamp fixtures helped to reduce the energy consumption.
MCGONEGLE: Pulse-start metal-halide lamp technology has improved the color uniformity, lamp life, lumen maintenance factor, hot restrike time and lamp efficacy factor. Low-mercury and low-lead lamps have reduced the owner’s hazardous waste disposal costs.
CSE: What about controls? Has integration with building-automation systems affected your selection of components?
MCGONEGLE: Integration with building-automation systems has limited the selection to systems with Bacnet, LonWorks or BAS-vendor-specific drivers.
BYRAIAH: New technology has changed the whole lighting control process. The latest improvements in motion sensors, occupancy sensors and photo-sensors offer easy integration with building energy-management systems.
Also, a building energy-management system helps facility owners monitor the lighting system constantly, measure the energy consumption, schedule the fixture cleaning and replacement and keep track of operation and maintenance costs.
FETTERS: The most exciting control we have recently seen demonstrated is an electronic metal-halide ballast for dimming higher wattage lamps. At least one manufacturer now has a model for the highly popular 400-watt metal-halide lamp and for the new 350-watt pulse-start lamp. These models operate the lamp using high frequency. The advantages of this design include increased lamp life, color consistency, lamp efficacy, lumen maintenance and energy savings.
The best control for warehouses that are occupied part of the time, but have full-time lighting systems, is a high/low, or two-level control. Most manufacturers of high-bay luminaires now make some type of high-low control that they can provide as an option. The two-level control lowers the lighting level-and the power-when there is no occupancy, when there is sufficient daylight to lower the HID lighting system or from a time-of-day control such as a building-management system.
CSE: Have any problems or disadvantages been encountered with any of these new technologies?
MCGONEGLE: I have found that the limited availability of new technology components from local distribution channels can cause maintenance and stocking problems for end-users.
BYRAIAH: Any new technology will always have some bugs. In one instance, we found that the HPS lamps with bilevel ballasts-using auto-transformer type reduced volt starter-dropped off at the start of a large compressor motor because the local utility had a poor distribution system.
FETTERS: The only concern we have is that the projected higher lumen-maintenance values we have designed with for pulse-start metal halide are not realized.
Know the task at hand
CSE: In general, what are some of the key concerns and pitfalls to be avoided when designing and planning industrial lighting systems?
FETTERS: Our main concern is that the lighting system may be designed and laid out before the visual tasks are even known for the occupants. If the system is only going to be an ambient system and there is going to be additional task lighting, this is OK. However, the overhead system is often expected to be the only lighting and that is where inadequate lighting often results.
BYRAIAH: We need to address energy efficiency, lamp color, lamp life, operation/maintenance cost and initial cost. Also, we must pay attention to whether the proposed light fixture or lamp can work in extreme temperature or with motion sensors.
Additional concerns are the availability of replacement fixtures and the reliability of the manufacturer.
MCGONEGLE: Avoiding production downtime during installation and maintenance of the lighting system is a major concern. The use of power hooks and modular wiring can simplify the maintenance and relocation of lighting systems. Knowing the hazardous location classification of the areas before designing the lighting is critical. Specifying the rated ambient temperature of the luminaires is important in industrial applications to avoid short life of components.
CSE: What role should the lighting designer and electrical engineer play in dealing with power-quality problems in the electrical distribution system?
BYRAIAH: The electrical engineer can play a significant role in identifying the power quality problems in the early stage of any new project design, whether they are caused by lighting systems or by poor utility distribution system.
The engineer can educate the facility owner that the electronic ballasts produce an abundance of third, fifth and seventh harmonic currents that cause voltage distortion, increased neutral currents, reduced system power factor, overheated conductors and electronic-equipment failure.
Also, the engineer will be able to design preventive measures in the building interior wiring system to address voltage sags caused by frequent starting/stopping of large motors. If the voltage drop is too steep, the light fixtures dim down when large motors start as the utility power supply is poor.
FETTERS: Nonlinear loads are the cause of most power-quality problems on a facility’s electrical distribution system. Controlling harmonics at the source is the easiest way to deal with this issue. For critical applications, this may mean using more fluorescent lighting with electronic ballasts rated at less than 20-percent total harmonic distortion (THD).
MCGONEGLE: The lighting designer should be specifying high power-factor ballasts with a THD of less than 10 percent. The electrical engineer should be specifying K-rated or harmonic mitigating transformers and dedicated or oversized neutrals. Specifying zero-crossing switch controls in occupancy sensors and relays will minimize inrush transients.
CSE: What are the primary considerations in retrofits?
MCGONEGLE: Improving the light level and energy savings. The more energy efficient HID and fluorescent sources typically allow increased light levels without increasing the watts per square foot or requiring additional electrical distribution. The spacing to mounting height ratio is a consideration when reusing existing mounting locations.
BYRAIAH: The primary considerations are energy savings, improved lighting quality, long lamp life, reduced operation/maintenance costs and utility-incentive programs.
In some existing facilities, owners are replacing the incandescent lamp fixtures with fluorescent, metal-halide or HPS fixtures to reduce energy and improve lighting levels. Some utilities are encouraging this with energy rebates and incentives.
FETTERS: We like the kits that convert 8-foot slim-line or high-output fixtures to 4-foot T8 lamps and electronic ballasts. The 8-foot T8 lamps and ballasts are often too expensive to get a decent payback.
The primary consideration is quality of work. This is the reason we have moved from specifying retrofit to specifying relighting projects. Relighting not only provides the additional opportunity to change the parameters of the lighting system, but more electrical contractors know how to install new fixtures than know how to retrofit fixtures well.
Limiting energy usage
CSE: Depending on the type of facility, lighting can account for a large part of total energy consumption. How will recently proposed new energy standards that seek to limit lighting power affect designs?
BYRAIAH: The proposed new energy standards pose a challenge to design as the lighting power budget gets reduced.
To reduce the lighting power, we have used metal-halide pulse-start lamps in lieu of regular metal-halide lamps, used acrylic-lensed high-bay fixtures in lieu of aluminum reflectors and also painted the ceiling white. We have also used bilevel light fixtures that work in connection with motion, occupancy and photo sensors to lessen the lighting load whenever possible.
FETTERS: In many commercial buildings, the lighting system consumes approximately 30 to 40 percent of the total energy, while the lighting in industrial or manufacturing facilities consume much less. Warehouses are one notable exception, where lighting systems take up a higher percentage because of the lack of manufacturing machinery.
The IESNA/ASHRAE 90.1 has input from the IESNA application committees, including the industrial lighting committee. Using advanced lighting equipment, new and relighting designs can easily meet these lowered power-density requirements.
MCGONEGLE: Designs that comply with the proposed energy standards lighting power budgets will have HID lighting sources, more automatic controls, more task-oriented lighting and less overall general lighting. Energy standard ASHRAE 90.1 exempts manufacturing or industrial processing buildings from compliance.
M/E Roundtable Participants
Byron Byraiah , PE., associate/senior project electrical engineer, Setter, Leach & Lindstrom, Minneapolis, Minn.
John Fetters , CEM, electrical engineer and principal, Effective Lighting Solutions, Columbus, Ohio
John McGonegle , senior electrical engineer, KJWW Engineering Consultants, Rock Island, Ill.
Jeromie Winsor , moderator
Applying a Standard: Typical light levels in food distribution and processing centers (with high-pressure-sodium (HPS), metal-halide (MH) and fluorescent (FL) lamps):
|Aisles (10 ft. wide)||20-30 foot-candles (fc)||HPS or MH|
|Loading dock||40-50 fc||HPS or MH|
|Produce storage aisles||20-30 fc||MH|
|Assembly and packaging||50-60 fc||HPS or MH|
|Processing||60-100 fc||MH and/or FL|
Typical light levels in manufacturing facilities (with skylights and task lights supplementing the general illumination):
|Assembly and packaging||50-60 fc||HPS or MH|
|Manufacturing||30-50 fc||HPS or MH|
Source: Byron Byraiah, P.E., Setter, Leach & Lindstrom, Minneapolis