A lamp or lamp-ballast combination may produce light very efficiently, but if it's installed in an inefficient luminaire or Lighting Fixtures, the overall system efficiency may still be poor. The best luminaire or lighting fixtures manufacturers will design their lighting fixtures around specific lamps to optimize the amount of light delivered to the work area. For example, a luminaire or lighting fixtures designed specifically for a compact fluorescent lamp can deliver almost 10 times as much illumination as an incandescent fixture fitted with the same compact fluorescent lamp.
Luminaire components include reflectors, diffusers—which absorb some of the light from a lamp—and polarizing panels. Reflectors can be used to direct more of the light produced by the lamp out of the luminaire onto the work area. Polarizing panels can sometimes increase the contrast of a visual task.
When comparing luminaires, it's important to understand the following performance characteristics:
Illuminance of Lighting Fixtures — the amount of light that reaches a surface. It's measured in footcandles (lumens/square foot) or lux (lumens/square meter).
Luminaire Efficacy/Efficiency Rating of Lighting Fixtures (LER) — the light output (lumens) per watt of electricity use. The LER is part of a voluntary efficiency program for manufacturers under the National Lighting Collaborative, which was facilitated by the Energy Policy Act of 1992.
Before selecting luminaires or lighting fixtures for an office building, factory, warehouse, and even parking lots, it's a good idea to consult a certified lighting designer. A lighting designer will not only help you find the most energy-efficient luminaires, but also provide lighting that makes for a comfortable and more productive work environment.
Today, energy-efficient commercial lighting design includes more than just the ambient or general lighting of a workspace, such as the use of ceiling luminaires or lighting Fixtures. When designing or retrofitting the lighting, the general illuminance can be reduced if task lighting is implemented properly into the overall design. Task lighting can result in significant energy savings and improved visibility for workers. The Illuminating Engineering Society of North America has established a procedure for determining how much illuminance is needed for a given task. The procedure takes into account several factors, including type of activity, characteristic of visual task, task's required speed and accuracy, and reflectance of the task's background. In turn, this procedure will help determine what type of luminaire(s) would be appropriate.
Other ways to save energy in commercial buildings are to install energy-efficient exit signs and parking lot luminaires. Incandescent exit signs may have a lower first-cost, but they'll cost more money in the long run through higher energy costs. When purchasing exit signs, look for the ENERGY STAR® label. ENERGY STAR-labeled exit signs operate on 5 watts or less. The most efficient light source technology for exit signs is light-emitting diodes (LED). The most popular parking lot luminaires use energy-efficient, high-intensity discharge lamps or low-pressure sodium lamps. But the most efficient light source technology for outdoor use is outdoor photovoltaic lighting.
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