Value-added lighting: for the greatest value, look beyond first costs when selecting today's lamp technologies.
Lowered energy costs, however, should never be considered the sole determinant in the specification of lighting systems for new and existing buildings. Today's savvy professionals must consider non-energy-related lighting concerns as well, from lighting quality and worker productivity to maintainability. Best value goes well beyond lowest first costs, particularly when selecting lamps -- incandescent, fluorescent, or high-intensity discharge -- as part of a lighting solution.
Consider the following when selecting a lamp:
* Color temperature or chromaticity (Correlated Color Temperature) is the color appearance of the light that comes from a light source and is measured in Kelvin (K). Lamp types are designated as "warm," "neutral," or "cool."
* Color rendering, measured on a color rendering index (CRI) scale of 0 to 100, is the ability of a light source to represent colors in objects. A higher CRI is referred to as high-quality light because objects and people look more appealing and natural, or visual clarity is increased.
* Efficacy, measured in lumens per watt (LPW), is the rate at which a lamp is able to convert electrical power (power in, expressed in watts) into light (power out, expressed in lumens).
Incandescent light is rich in yellows and reds, making it look "warm." Because of its construction (much of the energy is wasted in the production of heat, a further liability requiring subsequent removal by air-conditioning), an incandescent lamp is the least efficient of the general lamp types. Lamp life is short, ranging from 500 to 2,000 hours. However, the primary benefits of incandescents include: excellent color rendering; ability to direct light accurately; lower initial cost; easy installation since no ballast is required; and dimming capabilities. Halogens, which are descendants of the incandescent family and used extensively in retail applications, are more efficient in both life (2,000 to 4,000 hours) and lamp output (generating about 30 percent more light).
Since its introduction during the 1938-1939 World's Fair, fluorescent light has proven itself to be one of the most energy-efficient systems in lighting applications. Sized in wattages and diameters, fluorescents are available in a complete range of color combinations. Considered somewhat the "standard" for office buildings, schools, and other commercial installations, fluorescents are shadowless light that fills a room. Although ballasts built into the fixture are key to their operation, requiring more extensive installation, fluorescent lamps start quickly, produce low heat, and have an extremely high life (up to 24,000 hours). For years, the 40-watt T12 lamp was considered standard. By reducing lamp diameter and employing rare-earth phosphors to improve both color rendering and efficacy, the lamp industry introduced the 32-watt T8 lamp in the early 1980s, which has become both the contemporary standard for new construction and an increasingly popular retrofit replacement for existing T12 lamps.
Compact fluorescents, an incandescent replacement with a life of up to 10,000 hours, good color rendition, and high energy efficiencies, are available in replacement tubes (for direct incandescent applications) or as a one-unit lamp/ballast.
High-intensity discharge (HID) lamps, which include a family of metal halide, mercury vapor, and high-pressure sodium, are very efficient light sources most applicable in large stores, warehouses, auditoriums, exterior architecture, and outdoor parking areas. Although HIDs usually ignite in stages (slower start-up), they deliver a large amount of bright white light over a wide area and have a long life (12,000 to 15,000 hours). Ballasts are a necessary part of each system; it is important to note, however, that ballasts and lamps are not interchangeable between different HID types. Generally, high-pressure sodium lamps are considered the most efficient with instant restrike capability; metal halide lamps provide the best color rendering for dramatic highlights and sports lighting; and mercury vapor lamps, with very long lives, are preferred for landscape and sign lighting.
One of the most important aspects of lighting design is selecting the correct lamp source for the task. In most instances, say representatives from lamp manufacturers, a good lighting system is a combination of systems.
"I think the question is `What do you want to achieve?' Are you looking at distribution of light to be a pleasant aesthetic? Are you concerned with glare or quantity of light? Do you want to create shadows? Certainly, from a visibility angle, for reducing glare, for improving color rendering, for improving the employee environment, we definitely promote a multiple systems approach," says Phil Sanders, commercial lighting applications specialist at GE Lighting, Cleveland.
Rick Barton, GE's senior specialist for outdoor industrial lighting, concurs with Sander's assessment, adding, "We also promote the systems approach; lamps as part of the lighting solution. Fixtures, energy sources, lighting controls all come into play, because if you apply our light bulbs properly with other efficient sources, you get the best of all worlds: good quantity of light with good quality of light."
Several lamp manufacturers are providing this systems approach to their customer services offerings. "We're working toward easing the burden on the end-user," notes Bob Horner, fluorescent product group manager for OSRAM Sylvania Inc., Danvers, MA. "That means making lighting less costly and more attractive at the same time. We want to increase the lighted quality in a space, but we're also sensitive to [other] needs ... [such as] the maintenance cost of owning a system and improving its performance once installed. A lot of the products we're now introducing address the cost of lighting to the owner: increasing relamping intervals; providing lamps that better illuminate; creating lamps with longer life."
Lamp technologies continue to evolve, adds Horner. "There are brand new technologies like the T5 fluorescent and the electrodeless fluorescent, but the industry is continually evolving existing technology as well, with improvements in color and color stability, as well as in bumping up light output [lumen maintenance] over the life of a lamp."
Obviously, more efficient, effective, longer-life lamps mean less disposal at the landfill -- good for building owners' pocketbooks, as well as the environment. When lamps do reach the end of their life, some industry manufacturers are ensuring their lamps pass the Toxic Characteristic Leaching Procedure (TCLP) hazardous waste test for disposal by producing lamps with low or reduced mercury content. "Our corporate philosophy is prevent now so you don't have to clean up later," says Steve Goldmacher, director of public relations for Philips Lighting Co., Somerset, NJ.
Whether interested in efficiency, effectiveness$ or the environment, facilities professionals must purchase lighting systems that bring value to their buildings. "What is the [project team] recommending vs. installing?" asks Goldmacher. "An owner has to stick to his or her guns to ensure [lighting] is done right. If it was speced for a reason, there should be no change based upon a low bidder."
Value, after all, is much more than mere first cost.
RELATED ARTICLE: Creating a Mood
When evaluating Vamps for any commercial application, an important performance characteristic is its Correlated Color Temperature (CCT), measured in Kelvin (K), which is an indication of the "warmth" or "coolness" of its appearance. Because a lamp's CCT creates the mood of a lighted space, it can influence buying behavior or work performance. Following is the influence of color temperature on mood and lighting applications:
Color Temperature Warm Neutral Kelvin Range 3000K 3500K Associated Effects and Moods Friendly Friendly Intimate Inviting Personal Non-threatening Exclusive Appropriate Applications Restaurants Public reception areas Hotel lobbies Showrooms Boutiques Bookstores Libraries Office areas Office areas Retail stores Cool Daylight Kelvin Range 4100K 5000K Associated Effects and Moods Neat Bright Clean Alert Efficient Exacting coloration Appropriate Applications Office areas Galleries Conference rooms Museums Classrooms Medical examination areas Mass merchandisers Printing companies Hospitals
RELATED ARTICLE: What's in a Name?
Consider the following terminology when evaluating performance characteristics of lamps:
* Correlated Color Temperature (CCT): A specification of the apparent color of a light source relative to the color appearance of an ideal incandescent source held at a particular temperature and measured on the Kelvin (K) scale. The CCT rating for a lamp is a general indication of the "warmth" or "coolness" of its appearance. As CCT increases, the appearance of the source shifts from reddish white toward bluish white; therefore, the higher the color temperature, the cooler the color appearance. Lamps with a CCT rating below 32000K usually are considered "warm" sources, whereas those with a CCT above 4000K usually are considered "cool" in appearance. Also referred to as color temperature or chromaticity.
* Color Rendering Index (CRI): A measure of the accuracy with which a light source of a particular Correlated Color Temperature (CCT) renders different sources in comparison to a reference light source of the same CCT (the ability of a light source to represent colors in objects). The highest CRI attainable is 100, on a scale of 0 to 100.
* Efficacy: The ratio of light output (lumens) of a lamp to input of power (watts), expressed in lumens per watt (LPW).
* Lamp Life: The number of hours that a batch of lamps will burn before half of them have failed.
* Lumen: A unit of measurement of the rate at which a lamp produces light. A lamp's light output rating expresses the total amount of light that the lamp emits in all directions per unit time. Light output ratings provided by manufacturers express the total light output after 100 hours of lamp operation.
Linda K. Monroe firstname.lastname@example.org) is editor-in-chief at Buildings magazine.