LED sources are a new solution for virtually all lighting needs and have the potential to change the way we live and consume energy. The largest limitation currently slowing the adoption of LED lighting is simply that it is new and not well understood. In addition, the LED lighting market is flooded with products of varying quality which cause many to discount the technology altogether.
This article explains the basics of LED Lighting and why it is a wonderful upgrade for most conventional technologies. As a result, you will have a better understanding of the technology and will be in a position to ask the right questions and successfully select the appropriate LED solution for your desired application.
Correlated Color Temperature (CCT)
Correlated color temperature, or CCT, is a metric developed to describe the shade of "white" light that a light source emits. LEDs are inherently monochromatic light sources and therefore typically use phosphors to create "white" light. The benefit to this is they are available in various CCTs and are ideal for a wide range of applications. For example, home environments typically feature warmer softer shades of light, such as the yellow/orange found in incandescent sources which have CCT values in the 2700K-2900K range. Opposite this, many institutional applications (surgery suites, science labs, etc) require a very crisp cool shade of light, such as the pure white found in some fluorescent sources which have CCT values in the 4000K and above range. LED lighting is available in both of these options, as well as everything in between. This means they can aesthetically enhance virtually any environment or application.
Color Rendering Index (CRI)
The color rendering index, or CRI, is a metric used to determine how well a light source reproduces the colors of an object in comparison to ideal lighting conditions. It has been used to compare the color rendering quality of incandescent, fluorescent, and HID sources for over 40 years. As LEDs are very different from conventional lighting sources, revised color rendering metrics are being developed. However, it is typically agreed on that LED sources with a CRI value of 80+ have good color rendering abilities. The differing quality of LED lighting often results in varying CRI values. To help ensure color quality, one of the Energy Star requirements for LED lighting is to have a CRI value of 80 or above.
The single most important factor in determining the performance and quality of an LED source is temperature. The thermal stress on LEDs caused by high operating temperatures will: cause a shift in CCT, reduce light output, and significantly shorten life. This is the reason why many of the LED light sources have a large aluminum heat sink integrated in the lamp body, using passive cooling to dissipate the heat generated by the LEDs. It is very important to understand this because applications such as recessed lighting restrict the flow of air around the lamp reducing the performance of passive cooled devices. This is especially true in residential applications where the down light fixture is designed to restrict air flow into the ceiling and the outside of the housing often comes into contact with insulation.
Another consequence of using a large aluminum heat sink is the much increased weight of the LED lamp relative to the incandescent source it is replacing. This may become a significant consideration in use with track lighting where the added weight does not permit the fixture to direct the light due the hinging not being able to support the added weight.
To overcome these problems with passively cooled lamps, there are more advanced thermal solutions that utilize active cooling to not only eliminate the need for the heavy heat sinks, but increase quality and performance. Furthermore, more sophisticated products incorporate thermal sensors that maintain the LEDs within a specified thermal range and compensate for changes in application to ensure product life and maintained performance.
LEDs have the ability to be dimmed, but not all LED lighting systems are made dimmable. A product's dimming capability is often specified on its packaging and/or in its specification documentation. Unlike incandescent sources, the efficiency of LED sources increases as the power is reduced. Hence, the energy savings becomes even greater when LED lamps are used in a dimming application.
However, issues can arise when using LEDs on traditional dimming systems. LEDs operate in a narrow voltage range which is controlled electronically by a power supply incorporated in the light source, whereas incandescent sources operate over the entire range of the supply voltage. This can often cause dimming issues, such as flickering of the LEDs, in certain systems. The more sophisticated products are capable of working on both standard and electronic dimming systems, and manufacturers will typically provide the customer with this information.
When selecting an LED reflector style lamp, or any reflector style lamp for that matter, it is very important to understand the full application in which the lamp will be used. For example, if a 10 degree spot lamp were to be used in a kitchen with typical 8 foot ceilings, the counter top would most likely have very bright circles of light with very dark areas in between. This is because at 8 feet the lights are only about 5.5 feet above the counter, so the diameter of the beam is only about 11.5 inches. The same lamp in a kitchen with a 16 foot cathedral ceiling would have much smoother lighting on the counter top because the beam diameter would be about 2' 4.25". The higher quality LED products will have taken these types of applications into consideration during the design development phase, so these companies will often provide the lighting design tables describing the change in beam widths and intensity values at different heights and different angles as a part of their product literature.
LED lighting is significantly more expensive than conventional sources, which is often a major cause for consumer hesitation. The important thing to realize is that despite the increased upfront cost, the tremendous savings in energy usage and the greatly extended life often equates to quick payback periods and prolonged financial savings. Furthermore, countless government agencies and utility companies offer substantial rebates for the purchasing of LED lighting because they understand the potential for large energy savings. Some of these rebates can nearly cover the entire cost of purchasing LED lighting, so it is important to find this information for your local area.
LEDs are safe, high-performing, continually-advancing light sources that outperform conventional technologies and are ever-expanding to virtually all applications and environments. The broadening portfolio of applications, as well as the increasing realization of how LED performance compares with other lighting solutions, speaks to the needs of ecologically- and economically-conscious companies and consumers interested in the double bottom line of financial and environmental sustainability. This is why most industry experts, technology developers, and government officials agree that LED technology is the future of energy-efficient and cost-efficient lighting
About PowerSecure Lighting: PowerSecure Lighting designs and manufactures the lighting industry's highest-performing LED lamps and fixtures. With superior lumen output, center-beam candlepower, and overall aesthetics and performance, PowerSecure Lighting's LED products enhance the retail, supermarket, commercial, museum and hospitality environments of the world's leading brands. PowerSecure Lighting relentlessly pushes the innovation envelope to create products that replace traditional lighting technologies with zero compromise to aesthetics and performance. To learn more about PowerSecure Lighting, visit us in person in Stamford, Connecticut, or online at PowerSecureLighting.com.