MisLED? Fact and Fiction of LED Lighting

 

Not many could argue that LED (Light Emitting Diode) Technology is the  

hottest thing to hit the Lighting Industry within the last few years.  

Whether attending a trade show or picking up the latest trade  

magazines, it is very hard to avoid the buzz of LED Lighting. While  

exposure to this technology continues to gain momentum in the public  

eye, there seems to be a lot of questions around LEDs among  

manufacturers, specifiers, distributors, and industry outsiders. This  

is particularly the case regarding how the technology works and  

the proper applications of the product.  

 

The reality is that LED technology has been around for quite some  

time. The original LED technology was discovered in the early 1900s.  

Electricity was applied to the semiconductor Silicon Carbide and 

produced a very low level of light, too low for any practical use.  

Since that time, there have been obvious improvements in the  

design and manufacture of products that have lead to the LEDs  

that we are now seeing in the marketplace.  

 

Why the recent attention to this technology?  

 

In light of the recent energy crisis and the flood of newer more compact  

fluorescent technology, it becomes clear. Advances in energy efficiency  

and decreases in production costs have made LEDs a new sustainable  

solution for lighting. The big questions at hand are “How do LEDs truly  

function?” and “What are the proper applications of the product?”  

 

How LEDs Function  

 

Light Emitting Diodes work very differently from common lighting  

products. Very simply put, LEDs are just miniature electronic devices  

that emit light. Whereas a common incandescent light bulb works by  

heating a filament that burns hot enough to produce light, LEDs are  

illuminated by the movement of electrons in a semiconductor material  

and operate at a significantly cooler temperature. As there is no  

true white LED, visible white light is achieved in one of two ways.  

Either a combination of three LEDs emitting Red, Green, and Blue light,  

or a phosphor coating is placed over a Blue LED, both of which is  

expensive to manufacture consistently.  

 

Currently the limitations of the technology for traditional lighting  

purposes are that it is a single directional point source that at 

maximum energy efficiency produces only low levels of light and  

like all electronics, is sensitive to heat. Like other light sources,  

LEDs produce more light when driven at higher wattages, but  

unlike other sources their efficiency drops dramatically as thermal 

management is needed to protect the electronics. However the  

benefits that distinguish LEDs from other light sources are they  

are small in size, do not emit ultraviolet radiation, and can  

operate at very low wattages while producing light efficiently  

and for a very long time.  

 

Proper LED Applications  

 

What about the proper application of this technology? Due to the  

availability of various color temperatures and intensities, LED  

technology has found a vast array of applications in the construction  

industry. Outside of color changing theatrics, the majority of current  

LED lighting applications is task and accent lighting. Whether you are  

illuminating cabinets, coves or stairways, LED lighting is an  

attractive lighting solution.  

 

As a point source, LEDs can collectively direct light well to where  

you need it. When choosing an LED product for task  

or accent lighting, you might consider the following:  

 

1. What is the lumen efficiency (lumens per watt) of the fixture? 

2. Does the product manage glare? 

3. If driven at over 1 Watt per LED, is there sufficient heat sinking  

in the fixture?  

4. Is the color temperature of the LEDs consistent? Is the color  

temperature consistent with the other fixtures used in the space?  

5. How do the costs compare to other options for the life of the  

fixture? 

 

But how well do LEDs serve as a general illumination solution? Since  

it differs from traditional general illumination sources tremendously  

in physical characteristics, strengths and weaknesses, this becomes a  

monumental challenge. If put into fixtures designed around traditional  

lamp sources, do LEDs even do as good of a job? Seemingly, this is a  

race that will not be decided today, however the age-old tenet of "Let  

the buyer beware." comes to mind. Here are several factors a  

cautious buyer will be required to consider:  

 

What color type or temperature of light is needed?  

 

Color temperatures for LED lighting products currently on the  

market range from 2700 Kelvin to 6500 Kelvin. 2700K provides a  

very warm light with yellow and red hues while higher color  

temperatures provide cooler crisper white light with bluer hues.  

Like most aspects of design, color temperature is a function of  

personal preference. 2700K brings out red tones better and  

4100K brings out blue tones better. As a point of reference, a  

traditional Edison lamp is around 2700K and noon daylight is well over  

6000K. If using LED fixtures for task lighting, such as under cabinet  

lighting for food preparation, you may consider using a mid-range color  

temperature. Xenon white light is approximately 3000K and is becoming  

the preferred color temperature for task lighting. In contrast, if  

using for general illumination in a living room or dining room, you may  

want a lower color temperature to create a subtler or warmer  

atmosphere. Consumers often complain that LED recessed lighting is  

“too bright." This could be due to the glare of the LED or simply due  

to the higher color temperature.  

 

What reflectors or diffusers are used to control the light?  

 

Light control through the use of reflectors or diffusers also has a  

tremendous impact as to LED fixture selection. Whereas most light  

sources emit light in all directions, LED emits a tight beam in one  

direction. Because of this LED light cannot be effectively dispersed  

utilizing commonly used reflectors. The challenge to manufacturers is  

to develop diffusers that can cut glare and disperse the light without  

drastically cutting the efficiency. For example, nearly 60% of light  

is lost when passing through standard acrylic diffusers. This is one  

factor that certainly adds to the high cost of the product.  

 

What are the limitations of the other components?  

 

LEDs require a driver to operate. This is comparable to a ballast for  

fluorescent lighting. Essentially an LED driver converts AC power to  

DC power at a constant regulated rate. This prevents fluctuations to  

the LED diode that would show inconsistent light levels and possible  

damage due to abnormal current situations. What are the limitations of the  

drivers? Two common limitations of the drivers seem to be centered on  

dimming and the life of the product. Since drivers and dimmers need  

to have a minimum load to operate, dimming can become a challenge. Pay  

close attention to those products which are advertised as dimmable. While  

they certainly may be able to be dimmed in the traditional mode, colors  

may shift. If using PWM (pulse width modulation), the LED can be dimmed 

from 100 to 5 percent without noticeable color shift and strobe. Pairing  

of dimmers and drivers is important to the successful operation and  

dimming of LED systems.  

While LEDs boast up to 50,000 hours, the life of drivers may also be a  

limitation.  

 

 

What kind of budget are you working with?  

 

As part of the Green initiative, we have heard, the term sustainability  

used somewhat loosely. In general, sustainability refers to the  

economical viability of using various solutions to address energy  

concerns. In other words, can you afford the up front costs of the  

solution? In most cases you can calculate a break-even point of energy  

savings. However if recouping the costs are several years down the  

road, the tough question needs to be asked as to whether or not it is a  

sustainable solution for the end-user. While some people are looking  

to commit to Green solutions for environmental reasons, the economic  

side cannot be ignored. Other light sources may be a more efficient  

and economical solution for meeting the same lighting requirements.  

The range of low-voltage halogen and fluorescent lighting should be  

considered in the design. Finally, the speed of technology advances in  

LED efficiency makes lamp replacement a real concern in the design of  

the fixture. Should an LED need replacement three years down the road,  

will the replacement be economical? Will it be available?  

 

What are your trying to accomplish by using LED lighting as a solution?  

 

The final question that needs to be answered by the end user is “why  

LED”. Do we want to be Green? Putting the right amount of light in  

the right places is still the greatest opportunity for efficiency  

gains. Energy efficient designs typically incorporate a variety of  

lamp sources for different applications. Do we want LED in our homes  

so we can show it off to the neighbor? There is no doubt that a great deal 

of LED product is being sold on this factor alone. As the consumer  

becomes more educated on sustainability, we may see a dramatic shift  

even more to this kind of technology. It is also possible that when the  

sustainability question is raised, other technologies may be considered,  

such as compact fluorescent lighting and dimmable low voltage lighting.  

As the demand and production increases on LEDs, the technology will  

improve and costs to the market will certainly decrease making it more  

sustainable to the masses. With regards to where LED is actually  

used…the verdict is still out.  

 

This article was written by Michael Hadank, National Sales Manager  

of WAC Lighting Company. The firm can be reached at 1.800.526.2588 or  

on the web at www.waclighting.com.