Lighting the way to savings

It's worth crunching a few numbers 
just to find out how much

It doesn't take an advanced degree in math ematics to calculate the cost of operating an industrial lighting system. You start by determining the system's connected load, that is, the sum of the wattage of the lamps multiplied by a factor to account for ballast losses--typically 1.2 or less. Manufacturers can provide exact numbers. Then divide by 1,000 to derive kilowatts. Multiply the connected load by annual hours of use--assuming 100 percent output 100 percent of the time--multiplied by the utility rate--often expressed as an average that also includes consideration of demand charges--to obtain yearly utility charges.

In addition, you must account for the annualized cost of replacement lamps, the value of the time spent replacing lamps and cleaning luminaires, and such other factors that you wish to consider. For example, you may want the annualized cost of ballast replacement or system depreciation. As such, given a two-shift plant operation with 200 workers per shift, the annualized cost of lighting system operation and maintenance is likely to be $25,000-$30,000. This assumes the system used 6,000 hours each year, at an average $0.08 per kWh. No news there!

What may come as a shock, however, is recognition that the real cost of your lighting might be ten times that amount or more if it fails to deliver the seeing conditions needed to maximize productivity and safety while minimizing reject rates and absenteeism.

The real bottom-line on lighting does not relate so much to the cost of system operation and maintenance as it does to the degree to which it fulfills its purpose. This is not to say that energy conservation is unnecessary; it's absolutely imperative. However, the amount of energy consumed by a lighting system bears no relationship to its purpose. Stated another way, lighting is not installed to consume energy; it is installed to support the ability of workers to get the job done. That support is optimized when the lighting provided is ideally matched to the visual requirements of the task being performed and the visual abilities and deficits of the individuals performing those tasks.

First things first
Before you begin a crusade for better lighting, recognize that all parties need to understand the relationship between lighting and the work being performed and the degree to which improved lighting affects the bottom line. In a situation involving 200 workers, and an average cost per worker--including Social Security costs and benefits--of $25,000, a 5 percent productivity increase is worth about $250,000 each year.

Recognize that the dollars associated with lighting are far in excess of the illumination system's annual operation and maintenance cost. Those involved should also recognize the need to gather more information about the specific procedures needed to achieve an optimized system.

The National Lighting Bureau may be one of the best sources of assistance. Sponsored by national trade associations, lighting system manufacturers, and agencies of the Federal government, the National Lighting Bureau provides a variety of educational materials to help managers make effective decisions about electric illumination.

The real goal, according to the National Lighting Bureau, should be what it calls high-benefit lighting. That is lighting that optimizes performance of the tasks for which illumination is needed, while minimizing the operations, maintenance, and energy costs.

The Bureau publishes a number of easily-read, extensively illustrated, and inexpensive publications relating to lighting systems in general and industrial lighting in particular.

One of the strong messages that comes through these guides, succinctly stated, is "Get help!" Do not, however, rely exclusively on sources of assistance without providing them input. While they may possess in-depth knowledge of lighting systems, they do not have in-depth knowledge of your plant and its lighting needs.

By being more conversant about the topic, you should be able to communicate effectively and thereby help the lighting designer develop a better system. Assistance is available from lighting consultants and illuminating engineers, including those who work independently as well as others who may be employed by utilities, manufacturers, electrical contractors, electrical distributors, lighting management companies, and contract cleaning companies.

While in-house personnel may have a comprehensive knowledge of lighting in general and know how to make the overall system more efficient, it takes highly-specialized training and experience to understand the relationship between lighting quality and productivity, reject rate reduction, safety, and so on.

Conduct an audit
The first step toward renovation for high-benefit lighting is conducting an audit. This involves an analysis and evaluation of the existing lighting system as well as an analysis of the tasks being performed, and the individuals performing them. This information determines electric illumination needs, the ability of the existing system to meet those needs, opportunities available to improve the existing system without renovation--as through enhanced maintenance activities.

An experienced lighting professional often can conduct an audit on a walk-through basis, complemented by a review of utility bills. At the same time, the professional should be able to identify alternative actions that you can take to enhance the existing system.

Query the utility
Many electric utilities offer rebates, low-cost loans, and other incentives to encourage industries to improve the efficiency of their lighting systems. The utilities' goal is reducing lighting energy consumption and thereby forestalling the need to build new generating plants. They also want to reduce the amount of pollutants emitted into the atmosphere.

The nature of the equipment targeted by the utilities help determine which alternatives will be most cost-effective. Some utilities have third-party provider programs through which an entirely new lighting system can be installed and paid for on a share-the-savings basis. These third-party provider programs also may be available independent of utilities.

Build in efficiency
The vast array of new energy-efficient equipment makes incorporation of energy conservation principles simple, for system upgrading or for replacement. Figure 1 illustrates some of the many lamp substitutions possible.

Figure 1: Flexible branch wiring system used in conjunction with "drop-in" troffers

Some lamps produce the same amount of light and consume far less energy while others produce far more light for the same amount of energy. The latter are most effective when the audit indicates that the existing amount of illumination-- illuminance--i s insufficient.

Luminaires--lighting fixtures--also have an important impact on efficiency. The most significant efficiency factor typically is coefficient of utilization. A coefficient of utilization of 0.70 indicates that 70 percent of the raw lumens produced by the lamps in the luminaire are distributed to the workplane.

Theoretically, the higher the coefficient of utilization of the luminaires selected, the fewer luminaires are needed to produce desired illuminance. Thus, a higher coefficient of utilization should reduce capital requirements as well as ongoing energy and maintenance costs.

High coefficients of utilization are not the only concern however. Another important luminaire rating factor is called visual comfort probability. The visual comfort probability indicates the amount of glare likely to be produced by a given luminaire when the lighting system is composed entirely of that luminaire type.

Glare is the sensation you experience when you are temporarily blinded at night by the high beams of an oncoming vehicle. Known as disability glare, it causes you to avert your eyes. Discomfort glare is more common and caused by a bright source in your field of view. You are not temporarily blinded by it because its lesser severity can be accommodated by tiny muscles that cause your eye to adapt.

Over time, however, these muscles can become strained, leading to eyestrain and headaches, absenteeism, and myriad other problems, including lower productivity and higher reject rates. For this reason, among others, lighting system retrofits that involve renovating luminaires by installing new reflective materials must be looked at with particular care. If that approach is used, it is essential to ensure that the quality of light provided by the renovated fixtures is what's required to support task performance.

The cost of renovation must be examined closely too. In the case of fluorescent luminaires, for example, it is common to recommend not only new reflective surfaces, but new ballasts as well. However, the cost of renovation may be very close to the cost of replacement, making the latter alternative something worth close review.

Build in flexibility
Flexibility often is accomplished through the use of lighting controls, devices almost always called for to boost or maintain efficiency. Dimming controls have the benefit of permitting workers to adjust lighting to meet their particular needs and preferences. They also permit lower lighting levels when work stations are unoccupied or when light is available through windows and skylights.

Flexibility can be accomplished through reliance on flexible branch wiring and movable luminaires such as those indicated in Figure 1. These luminaires are easily removed, permitting substitution of fixtures when tasks change and relocation of fixtures when the work area layout is modified. Again, being able to put the right kind of light where it is needed and when it is needed can be significant in enhancing overall quality and, thus, overall productivity, safety, and other positive benefits.

Build in good maintenance
The impact of good maintenance on overall lighting efficiency and quality cannot be stressed enough. Without maintenance, dirt and dust quickly build up on fixtures and lamp surfaces trapping light, lowering efficiency, changing light distribution, and affecting quality.

Fortunately, many industrial lighting designers assume that inadequate maintenance will be performed and, to compensate, they include additional compensatory lighting in the system so that adequate lighting is available despite inadequate maintenance. Unfortunately, that approach increases both initial and long-term operations and maintenance costs.

Accordingly, by resorting to high-quality maintenance, it may be possible to eliminate 10 percent to 20 percent or more of the installed lighting. High-quality maintenance allows lighting users to achieve a system that is far more efficient and actually provides better quality.

Don't wait
The value to be derived from high-benefit lighting can be extraordinary. In fact, lighting presents a unique opportunity to improve energy efficiency and enhance productivity at the same time.

Given the competition that American companies face with one another, and others throughout the world, optimizing existing lighting systems should be seen as a priority.

Consider the case of Superior Die Set Corporation in Oak Creek, Wisconsin. There, new lighting not only reduced lighting operating and maintenance cost by 45 percent, saving $2,148 per year, it also improved overall productivity and reduced downtime, saving an additional $42,836 annually. In addition it lowered the reject rate, reduced absenteeism, and enhanced security, benefits whose bottom-line values could not easily be calculated. The company earned a simple payback on its investment in less than 24 days.

A similar story unfolded in Elisabethville, Pennsylvania, home of Metal Industries, Inc., a manufacturer of metal-framed windows and patio doors. The strategy used to retrofit lighting in the company's 100,000-square foot plant was simply to increase the amount of light provided to workers. The results were extraordinary: Productivity jumped by at least 5 percent, worth $1.5 million each year. The reject rate was cut by 25 percent, producing annual savings of $200,000. Accidents were reduced, reducing related costs by $3,000, not including the value of reduced absenteeism--$225,000 per year--and lower insurance premiums valued at $3,000 annually. All told, the annual benefits had a value of more than $1.9 million, creating a simple payback of 1.5 days--37 hours.