Lighting technology is constantly evolving, with many of the latest developments targeted specifically at environmental concerns.
» By now, most North American lighting professionals have addressed sustainability on one or more projects. Once limited to a few forward-thinking buildings, the U.S. Green Build CouncilÆs Leadership in Energy and Environmental Design (LEED) requirements have become standard criteria for most government facilities, and common on academic and healthcare projects. This is not a North American phenomenon, either: the Chinese government has opened its first LEED-certified building and pledged to follow sustainable growth for ChinaÆs future, as a matter not of social conscience so much as of pure necessity.
As with a small lighting budget, sustainable practices necessitate changes in design approach and techniques, and in the choice of products and materials. As momentum has gained around the issue, manufacturersÆ offerings have improved. Today, there are a number of lighting technologies and products that make it easier to meet sustainability criteria.
For most applications, skinny fluorescent tubes rule. It is almost impossible to beat the 100+ mean lumens per watt of the latest ôsuperö T8, T5, and T5HO lamp and ballast systems. SIDEBAR: What is a Super 8 lamp? The most recent developments include amalgam T5HO lamps, which maintain rated lumen output over a wide range of temperatures. However, for a number of applications, the efficacy of skinny tubes is now challenged by ceramic metal halide, the latest of which can achieve almost 90 mean lumens per watt, with a color rendering index (CRI) of 85 or higher. And when it comes to display lighting, the efficacy of ceramic metal halide sets it apart from everything else. With lamps ranging from 20 watts on up, and in a variety of envelope styles from the tiny T4 up to a brilliant PAR64, the ceramic metal halide with an electronic ballast appears to be the energy-efficient choice of now and the near future.
The benefits of compact fluorescent lamps (CFL) have been touted for years. Compact fluorescents remain a good choice for use in downlights, wallwashers, and decorative lighting. Keep in mind that CFLs are typically about 60 mean lumens per watt, so they are not quite as good as skinny tubes or high-wattage HID lamps. But for demanding aesthetic applications where long lamps do not work, CFLs are often the best choice. Some of the more esoteric lamps are also worth considering. For example, the efficacy of induction lamps is like that of the compact fluorescent, somewhere between 50 and 60 mean lumens per watt. These sources are the king of long life (up to 100,000 hours), a worthwhile consideration in those hard-to-reach locations. Likewise, as practical white light LED lamps evolve, expect to use them more.
In order to achieve the high efficacy of the latest sources, efficient ballasts are absolutely necessary. Take, for example, the ôsuperö T8 lamp; using the efficient ôsuperö ballast, rather than a generic electronic ballast, saves 2 to 3 watts per lamp with no change in light output. Electronic ballasts make an even bigger difference when used with HID lamps. Metal halide lamps last longer and have higher maintained lumens when operated on electronic ballasts, and the internal loss of power in the ballast is reduced. Savings are achieved by a combination of improved ballast efficiency and significantly improved lamp lumen maintenance. In typical 400W metal halide applications, power savings are over 100 watts per lamp.
Efficient Indoor Luminaires
Using more efficient luminaires in conjunction with more efficacious sources is a dream combination for sustainable design. To meet this need, manufacturers have introduced a number of important products capitalizing on the latest lamps, aided by 95 percent or higher reflective specular or white surfaces, to achieve phenomenal overall lighting efficiency. For instance, it is now possible to achieve up to 85 maintained footcandles of general lighting at 1 watt per square foot using a lighting system that is an attractive improvement on the familiar fluorescent troffer. Likewise, imagine high-bay retail space, using the latest reflector technology that helps keep the luminaire clean: lighting levels of 50 to 60 maintained footcandles or more are possible at 1 watt per square foot with lamps that render colors spectacularly with CRIs ranging from 85 to 92.
Product improvements are not limited to just the standard vanilla options. Today, every manufacturer of lighting products is seeking to improve the energy performance of its product line, ranging from fabulous new American and European commercial luminaire systems that emphasize T5 and T5HO sources to a wide variety of standard and semi-custom decorative pendants, sconces, and chandeliers using efficacious sources. New developments in track lighting, including power-limiting devices and low-wattage HID, will revolutionize retail lighting to meet this need.
Dark Sky-Friendly Lighting
LEED is not the only standard that requires significant limitations to outdoor lighting: there are over 1,000 dark sky ordinances in the United States and Canada, and a new model lighting ordinance is under development jointly by the IESNA and the International Dark-Sky Association. The need for new lighting systems, combined with the call for replacing the majority of existing outdoor lighting, has inspired whole new families of products for everything from street lighting to sign lights. (Click here for dark sky friendly fixtures.) While it is easy to design contemporary dark sky-friendly luminaires, there are now traditional designs that retain the historic charm of antique lighting without throwing huge amounts of light into the night skyùor your bedroom window. Also, expect to see lighting systems that use very low-wattage ceramic metal halide lamps, LEDs, and other sources replacing high-wattage lights in rural and suburban areas. Imagine roadways outlined with LEDs or parking lots lighted at less than 0.5 footcandles with warm, incandescent-like light.
Controls: The Secret Ingredient
Because energy is the product of power (watts) and time, controls hold the key to energy management. Motion sensors and other current technologies are so effective, they are part of most energy codes. LEED goes beyond just saving energy, by actually awarding points on the basis of energy cost savings, forcing the use of daylighting controls and other techniques that cut lighting energy use at peak times.
Technology has evolved to make the most powerful control systems useable and cost effective. Plug-and-play wiring and communications systems are working to eliminate costly and complex hardwired analog controls, and digital programming of powerful control functions has become, at long last, a lot easier and more intuitive. As daylighting becomes a prominent part of lighting design work, specifying shading and other lighting control systems like louvers will become standard practice for lighting designers and architects. These systems must, in turn, be closely integrated with all types of electric lighting controls from daylight dimming to motion sensing. In the future, smart designs will enable the building to shed power, either when asked by the utility or, perhaps, when the price of electricity rises above an acceptable maximum rate.
The Mercury Issue
LEED-EB, a recently launched rating system for existing buildings, has taken a bold new step: in addition to rewarding energy savings, LEED-EB requires building managers to record and track the use of mercury in lighting systems. This will promote retrofitting with specific products that are both energy efficient and use ultra-low levels of mercury in most lamps. Approaching work on existing buildings, designers should generally favor T5 and T8 lighting systems for indoor lighting, and (as much as I hate to say it, given its ugly yellow hue), the use of high-pressure-sodium lighting for the exterior. Eliminate mercury vapor and traditional metal halide lamps, and minimize the use of compact fluorescent systems (which tend to have a lot more mercury per lumen than the skinny tubes). Incandescents and LEDs are mercury free, but make it difficult to meet efficiency criteria.
The Fall Out
As sustainable design matures and designers learn to do more with less, we can expect continuing refinement and increasingly tough requirements. The reason for change is obvious, and as more of these requirements become code, our industry and its products will evolve to meet the coming challenge. Now we must develop the design skills to match.
James Benya is a professional lighting designer and principal of Benya Lighting Design in Tigard, Oregon. He serves on the editorial advisory board of A|L.
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