As specifiers and end users began moving away from incandescent lighting three decades ago, they started utilizing high intensity discharge (HID) and compact fluorescent (CFL) lamps and fixtures for most commercial lighting applications. The inherent characteristics of these light sources prevents them from generating effective lighting in the desired areas, which creates wasted energy due to much of the light getting trapped inside the fixture.
Lamp and fixture design was simple, costs were relatively low, and these same sources were used to design a wide variety of products on the same platform. If you wanted greater lumen output, specifiers increased the wattage of a fixture or added more lamps with the same base. Compared with today’s LED lighting products, CFL, HID and incandescent lamps and fixtures were less efficient, operated at higher temperatures, offered low efficacies, required higher maintenance and energy costs, and were costly to dim. Although considered energy efficient during that time, CFL and HID fixtures and lamps did not offer the best quality of light, compared to halogens and other incandescents; HID lamps and fixtures have more than two color shifts during their lifetime, and CFLs have non-linear dimming properties where dimming does not directly correlate to the percentage of energy savings.
The energy crisis of the 1970s attracted national attention to America’s escalating consumption of energy from finite natural resources, which led to the emergence of utility incentives for energy-saving lighting technologies from the 1980s to the present. Government enticements offered deductions to commercial building owners that implemented energy efficient lighting solutions within their building interiors, and helped create a shift in the manufacturing and design of energy efficient lighting technologies. Financial incentives from utilities and other organizations helped expand the compact fluorescent market by offering compelling financial incentives to offset the incremental costs of trading-up to a highly efficient and long lasting technology. These activities helped spawn the emergence of organizations that identify and qualify energy efficient lighting products, such as the DesignLights ™ Consortium (DLC) and the Lighting Design Lab (LDL).
These economic, social and legislative activities, including LEED and ENERGY STAR® standards, have perpetuated the general movement towards “green” strategies and energy efficient products, and helped commercial professionals and end users move away from older, less efficient light sourcing.
Emergence of LED Lighting Technology
As a result of this “green” movement, the industry began to embrace light emitting diode (LED) light sources and fixtures, which have established a new benchmark of energy efficiency, performance, and quality during the past five to 10 years. LED light sources and fixtures are now adaptable to building control systems, offer a long life exceeding 50,000 hours, and provide energy and maintenance savings. LEDs characteristically offer a high color rendering index (CRI) and have the benefit of color control, where the correlated color temperature (CCT) remains the same regardless of dimming or lifetime. Manufacturers are also able to control glare in LED products by increasing the illuminating surface area. Also, because LEDs are a much more compact light source per lumen than traditional light sources, they allow for much more versatility in fixture design.
LED design and manufacturing challenges include high initial costs, which are declining every month as technology advances with more efficient development and increased production. There are still market-wide inconsistencies in the fixtures, lamps and drivers; their life expectancy claims and applications; and the language describing these products on the market.
Over the years manufacturers have determined that commercial-grade, off-the-shelf components cannot provide high enough life expectancies and lumen performance, and that the most common failure point in LED fixtures is not the LEDs themselves, but rather the LED drivers. To resolve this challenge, LED innovators have forged a value-engineered approach by developing highly efficient, thermal- and lumen-balanced light engines, and higher capacity drivers. The result is LED products that combine cooler operating temperatures, less thermal heat sinking, and the usage of a greater number of LEDs to deliver higher lumen output, efficacy, and life with minimal wattage, cost and material waste. Higher wattage LED fixtures that yield tremendous energy savings on larger applications, such as those that replace 400-watt metal halide luminaires, drive the most substantial impact in the marketplace today.
Low-cost halogen and incandescent alternatives provide an increase in lumens by conveniently changing out a bulb with another that has a similar base construction. Unlike CFL and incandescent lamps and fixtures, LEDs require an individual design approach to each and every product depending on the specifications and applications. Street and roadway LED lighting is one example. LED roadway and street luminaires are designed to reduce upward light to meet dark sky requirements while yielding strong energy savings from converting conventional illumination to LED luminaires. Full cut-off beam spreads, with special optics, reduce light spill and help prevent light pollution while delivering the right light in the appropriate place in public spaces. High failure rate components were eliminated from LED fixture designs and commercial-grade components and technologies were employed to deliver true reliability with power systems consistent with the long lifespans of the LEDs.
The characteristics of LEDs as directional light sources enable them to be designed into fixtures and luminaires that project light, making them a much better candidate for applications that need directed light, such as street lighting. Also, LED light sources and fixtures offer the highest benefit when utilizing controls, compared to traditional light sources, due to the linear relationship between dimming and energy savings. For example, a fluorescent bi-level system at 50 percent only offers 20 percent energy savings, whereas an LED on that same system will see a 50 percent reduction in energy consumption. Unlike their inefficient counterparts, LED lighting fixtures will occupy commercial facilities much longer than ever before without servicing.
Incumbent technologies, such as HID, incandescent, CFL, and fluorescent linear have plateaued in development and cost, while LEDs are only in their adolescence, meaning that through value engineering and design, these products are going to become much more effectively priced. Demand is continuing to increase for LED lamps and fixtures in a multitude of commercial installations. Rebates generated from the DLC list provide the criteria on which utility companies can base their requirements for incentives.
LED chip package, as well as light source and fixture technology, are changing simultaneously, which enables cost reductions. LED chip package costs are directly dependent on the yield production of dies, which is up to 80 percent compared to 60 percent two years ago. Additionally, LM80 data prequalifies the lumen package of the LED for a fixture prior to light source or fixture manufacture. In combination with better bonding techniques, LED packages can sustain higher temperatures and operation at extended life. When manufacturing the end product, manufacturers have to pay special attention to electric static discharge, but beyond this, LEDs are the most rugged, robust light source available today. The latest generation of light sources is tested using LM79 standards, which allows for a true fixture-tofixture comparison dependent on delivered values, and not initial output.
The Future of Lighting
Now only in its infancy, Organic LED (OLED) fixtures, the latest generation of LEDs, will grow in significance in the lighting marketplace. While this technology is not currently priced to move into the mainstream for commercial use, the industry will see an increasing need for this highly flexible technology, which can be curved without using reflectors for high-end architectural applications.
On the controls side, the next stage will come from the integration of smart circuitry into the drivers in a single component, which will reduce costs. As we look for more areas to save energy, one direction is to implement more control over existing light. To accomplish this, there are two types of sensors that can be integrated into luminaire design: light and occupancy sensors. These sensors can be applied in the customization of individual, whole room, house, or building lighting experiences. Control over commercial environments with smart phone devices is also likely. There are products that are entering the market today with the ability to link lighting to building controls, converging mobile and sensing with lighting systems.
Overall, LEDs are changing the entire paradigm of lighting. In the next two years, it is predicted that many white LEDs will reach 250 lumens/watt, creating more light output with an additional 50 percent reduction in energy consumption.
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