Published In April 2001
Lighting in commercial, industrial, and institutional (CII) buildings is often the largest single user of electrical energy. The purpose of buildings is to support the work and leisure activities that they were designed to house. Lighting enables them to fulfill this mission. Lighting systems convert electrical energy into light energy effectively, efficiently, and safely. A lighting system’s ability to make this conversion over the life of the building goes beyond design and initial installation. Lighting systems must be maintained and upgraded if they are to continue to meet the customers’ needs. This article addresses the need for an effective lighting maintenance program.Lighting design assumes regular maintenance Lighting systems are designed assuming that they will be maintained on a regular basis. No matter how good the original design, luminaires, and installation are, the quality and quantity of light will deteriorate with time. Lighting designers and manufacturers assume that the lighting system will be maintained in accordance with their design assumptions and recommendations. These assumptions are factored into the lighting design in three ways: lamp burnout, lamp lumen depreciation, and luminaire dirt depreciation. Each of these three light loss factors is considered recoverable, because an effective lighting maintenance program can mitigate its impact. • Lamp burnout (LBO). The purpose of considering LBO is to compensate for burned out lamps that will not be changed out for long periods of time while the activity that is carried out in the space continues. If the facility has a good lighting maintenance program and burned-out lamps are replaced soon after they are reported, then lamp burnout should not be a design factor. • Lamp lumen depreciation (LLD). The light output of a lamp decreases gradually over its life; LLD addresses this loss in the lighting system design. Lamp manufacturers can provide LLD information about each type of lamp. LLD is an important factor when developing a lighting maintenance program for a CII facility. • Luminaire dirt depreciation (LDD). LDD is intended to compensate for light loss caused by dirt buildup on both the inside and outside of a luminaire. Lighting fixture manufacturers can provide information on LDD for their fixtures. Those luminaires that are susceptible to dirt buildup will require more frequent cleaning to maintain the design light level than others do. Mismatch between design assumptions and actual maintenance There can be a mismatch between the designer’s assumptions about maintenance and the facility’s actual lighting maintenance program. If significant, these differences can have a material impact on both the operating cost and performance of the lighting system. The lighting designer’s assumptions regarding maintenance of the lighting installation will determine the number of luminaires used, which directly impacts the lighting system’s operation and maintenance cost. If the lighting designer assumes a better lighting maintenance program than the customer will implement, fewer luminaires may be called for in the design and the needed quality and quantity of light will not be maintained over time. Burned-out lamps, dirty fixtures, and old lamps will result in significantly reduced light output that can impact employee productivity and morale. On the other hand, if the customer’s lighting maintenance program is better than what the designer assumed, the lighting system may be overdesigned. This increased number of lighting fixtures will not only result in greater first cost than necessary but also increased energy and maintenance costs over the life of the lighting system. Routine lighting maintenance Routine lighting maintenance is aimed at overcoming the impact of lamp burnout, lamp lumen depreciation, and luminaire dirt depreciation. It consists of two activities: cleaning and relamping. • Cleaning. Lamps, lenses, and reflectors should be cleaned on a regular basis in accordance with manufacturer recommendations. The cleaning interval depends on the rate at which dirt collects on these surfaces, which is determined by the design of the luminaire and its operating environment. Paragraph 15-2.1 of National Fire Protection Association (NFPA) 70B recommends periodic light meter readings be made and cleaning intervals be established when light levels drop between 15 and 20 percent corrected for lamp lumen depreciation. • Relamping. As lamps age, their light output decreases. Since each lamp’s life expectancy is different, the number of burnouts and group replacement intervals will vary. There are two general lamp replacement strategies: spot relamping and group relamping. •Spot relamping. Spot relamping waits until a lamp fails before replacing it and is a “run-to-failure” maintenance strategy when used exclusive of group relamping. Basing a facility’s lighting maintenance program on spot relamping is not typically the best strategy. Replacing only burned-out lamps when they fail is inefficient because lamp failure is random and increases with age. This results in electricians being continually on the move replacing lamps and disrupting the activity in the space where they are working. •Group relamping. Group relamping involves the replacement of all similar lamps in a building or area at about 70 to 80 percent of their rated average life. Group relamping is a preventive maintenance strategy where lamps are replaced before they fail and require spot relamping. Group relamping is often economical and desirable in many commercial, industrial, and institutional facilities. Group relamping balances the cost of disposing of a lamp that has remaining life with the cost of replacing individually failed lamps on an ongoing basis. Other factors to be considered A number of other factors should be considered as part of an ongoing lighting maintenance program. These factors go beyond routine lighting maintenance but are extremely important. These factors include the repeated failure of individual lighting system components, changes in the space being lit, out-of-tolerance system voltages, and the operation of lighting controls. Effective lighting maintenance programs should address all of these factors as well. Services the electrical contracting firm can provide its customer to address these factors include the regular review and analysis of the lighting system performance; the repositioning and adjustment of accent lighting when space layout and lighting needs change, the monitoring power quality and its impact on lighting, and maintaining and upgrading lighting controls as required. Keeping your customer up to date Considering the lighting system as part of the overall power distribution system, it is safe to say that no other part of the distribution system is so dynamic or visible. The lighting system is high profile, both from an energy usage and aesthetic standpoint. There is ongoing product innovation and improvement by lighting fixture and lamp manufacturers. These improvements address the light quality, energy use, maintainability, and flexibility of the lighting system. The electrical contracting firm is the link between its customer and the lighting manufacturer. Through this important link, the electrical contractor can assist its customer by calling attention to advances in lighting equipment and technology that could benefit the customer by reducing operation and maintenance costs or improving lighting quality, which can increase employee productivity and enhance sales. Developing a lighting maintenance program Developing an effective lighting maintenance program requires a partnership between the electrical contractor and the customer. One size does not fit all. The electrical contracting firm should start with an evaluation of the customer’s existing lighting system and lighting maintenance program. From there, the electrical contracting firm should develop options based on the customer’s operations and space usage. These options should include not only routine maintenance but also lighting system changes and upgrades that will improve the performance and effectiveness of the lighting system. In the end, the costs and benefits of each option need to be quantified and presented to the customer for his or her evaluation. There is no “right” lighting maintenance program for a particular customer. Selecting a lighting maintenance program is like any business decision, in that it is balancing a number of quantitative and qualitative factors and selecting the best given current knowledge and circumstances. This is why the lighting maintenance program should not be static. It should, instead, be reviewed and reevaluated on a regular basis. Acknowledgement This article is the result of ongoing research into the development of service contracting business by electrical contracting firms sponsored by the Electrical Contracting Foundation, Inc. The author would like to thank the foundation for its continuing support. Dr. GLAVINICH is Chair and Associate Professor of Architectural Engineering at The University of Kansas. He can be reached at (785) 864-3435 or email@example.com.