Unlike conventional sources, LEDs do not depend on heat to create light, nor do they contain a delicate filament or glass tube. Rather, LEDs are solid semiconductors that produce visible light when electrical current passes through them.
Most LED fixtures available today have been completely redesigned to accommodate the unique characteristics of the light source. They deliver efficient lighting with better control and distribution, which enables the fixtures to project light farther from the source, increasing the amount of space that can be illuminated with one fixture.
Understanding how LEDs work to deliver light can help facility managers maximize the potential of LEDs, resulting in a properly lit, energy-efficient environment.
Design with delivered lumens.
When incorporating LEDs into a lighting plan, it is critical to design with delivered lumens in mind. “Delivered lumens” refers to the total amount of light emitted by the luminaire, rather than the light source. For example, an LED tube may deliver 3,500 lumens per tube. (Most T8 fluorescent lamps deliver 2,800 to 3,200 lumens.) If three of these LED tubes are installed in a luminaire that is 65 percent efficient, they will produce 10,500 lumens in bare lamp photometry. That figure is then multiplied by 0.65 because the luminaire is only 65 percent efficient. The total delivered lumens in this example equals 6,825.
Because bare lamp photometry does not consider the losses that occur as a function of the luminaire, using it to perform a lumen-to-lumen calculation may lead to mistakes when designing for a facility. Whether in retrofits or new designs, using absolute photometry, which measures delivered lumens regardless of the source, is a better approach for achieving the appropriate light levels for a task or space.
Use LED directionality to your advantage.
Did you know that most LED tubes deliver light closer to 120 degrees around the lamp, while fluorescent sources generally deliver light 360 degrees? By keeping this directionality in mind, unintended consequences such as uneven distribution or glare can be avoided. Well-designed and integrated LED luminaires can account for this issue.
Incorporate lighting controls.
LED light sources are designed to dim. The low-voltage nature of an LED gives the dimming curve a nearly linear quality. This means that as the power to the light source is reduced, the light dims to a degree that is representative of the power reduction. For facilities that are looking to reduce energy costs, dimming LEDs to a lower level, or using controls to turn them off completely when a space is not occupied, can result in huge energy savings.
Task tuning, also called high-end trim, refers to the reduction of lighting levels in a space based on Illuminating Engineering Society-recommended maintained task light level requirements or user preference. LEDs make it possible for users to adjust light levels that are needed for a particular task. This level of control may not always be necessary or represent an efficient use of resources, especially in large facilities such as hospitals. For that reason, many facilities incorporate automatic lighting controls based on the function of the space.
Explore the vast range of LED fixtures and luminaires.
LEDs are now available in a wide variety of replacement lamps and luminaires, and smaller and more creative LED fixtures continue to enter the marketplace. LED replacement lamps are often designed in the shape of a bulb with a screw base to make replacement easy and familiar. LED luminaires are also available in almost every form, including troffers, downlights, spotlights, sconces, pendants, cove lightning, wall washes and linear lightning.
For lighting designers and facility managers, there is no limit to what can be achieved using LEDs. Understanding the unique characteristics of LEDs can help maximize the potential of this powerful, flexible and energy-efficient light source.