Simply put, the 50,000+ hour lifespan of high quality LED lights means that the initial cost of a light (bulb) is a smaller percentage of the Total Lighting Cost or "TLC" (the total cost of providing lighting to a space.) But, there is actually more to it.
Instant on advantages of LED
However, there are also many differences that are important that can be easily seen by the naked eye. One example of this is the directional nature of the light that is produced by LED lights. This enables the energy being produced to be emitted focused in a particular direction, rather than in all directions as with most traditional light sources. One side effect of the way traditional light sources emit light is that much of the light often is emitted in a (or many) direction(s) other than that which is desired. This is extremely inefficient because much of the brightness of the light is lost in the process of redirecting the light back toward the desired direction.
Another of the most obvious differences that occurs immediately when you turn on an LED light is the simple fact that the light turns on essentially immediately. In contrast, many traditional lights can take several seconds up to many minutes to turn on, and even longer if they are turned on and off, then back on again.
So, why is this?
E26, MR16, PAR 38, T8, GU10 - Bingo! (Or what do all of these lighting codes mean?)
One of the challenges with any new technology is that it takes time for people to understand it and how it may differ from other technologies that they have previously experienced. Such is often the case with LED lighting.
Most everyone is familiar with the traditional incandescent light bulb and equally familiar with the ways that have historically been used to describe the light emitted from these bulbs. For example, if I say, "this room should have a 100 watt light bulb in it," you likely know immediately what I am referring to and have a general sense that this would be a relatively bright reading light.
However, one of the challenges created because of the dramatically increased efficiency of LED lighting is that using a traditional power measurement such as 100 watts does not offer any precise information about how bright the light drawing this much power would be. For example, our company, Leading Edge Designs, carries a 75 watt LED light fixture that is bright enough to be used as a street light - a far cry from a 100w incandescent light!
Therefore, one of the challenges faced by the lighting industry as a whole is how to consistently measure (and describe) brightness across different technologies, especially when they can be drastically different in the magnitude of intensity. Currently, one of the common ways to describe brightness that can be applied to both traditional and new technologies is to use the term "Lumen." Wikipedia defines a Lumen as "the International System of Units derived unit of luminous flux, a measure of the total 'amount' of visible light emitted by a source." (Luminous Flux is further defined here...)
This certainly seems like a reasonable unit to use, since it measures the total "amount" of visible light, and in many ways it is very useful. However, a challenge is created because Lumens actually measure the total amount of visible light emitted by a source without regard to the direction this light is emitted. Because of this, it does not accurately reflect the amount of light that actually reaches the eye of an observer. Some reasons for this are uniform across technologies, such as the amount of dust and other particles in the air, so these don't impact a meaningful discussion of how "bright" a light is, because they tend to have a relatively consistent impact on different lighting technologies.
However, there are some reasons that the total brightness of a light source doesn't reach an observer's eye that are different because of the technologies involved. The ones I'd like to focus on today are directional light and reflected light intensity.
Traditional (incandescent, high intensity discharge, etc.) lights emit light in all directions. In contrast, LED lighting is directional, meaning that all of the light energy is emitted in the direction the light is pointed (in whatever beam pattern it is designed to produce). For example, most Leading Edge Design lights are designed to emit a 120º beam pattern, so all light is directed within that 120º pattern. Traditional lights emit light in all 360º, meaning that essentially 50% or more of the light emitted is directed away from the intended illumination. Often times, light that is initially emitted in the wrong direction is reflected back generally toward the intended illumination point, however, this light looses brightness along the way, especially since some of the reflected light is reflected back into the original light source or is refracted along the way.
So, what does all of this mean? A rough rule of thumb to use is that, in order to compare an LED light source to a traditional light source, one must reduce the lumen results of the traditional light source by up to 50% or greater to account for brightness lost getting to the observer's eye. I call this "Usable Lumens." Who knows, maybe the industry will pick this term up to help better explain how two lights compare to each other. Either way, it is in part because of this difference in "Usable Lumens," that a traditional light rated at 20,000 Lumens would be observed to be less bright that a 10,000 Lumen LED light under the same conditions.
Another common way to measure light intensity that is often used in regulations such as OSHA (Occupational Safety and Health Administration) standards is the unit of measure foot-candle. I'll discuss the difference between this and a Lumen in a future post. In the meantime, you can learn more about the latest in LED light fixtures at our website, www.LED-ltd.us. Please post a comment or question on the blog, and we'll get back to you as soon as possible.
How do LED lights save you money?
There are two basic ways that installing LED lights can save you money. The first is pretty obvious, the second one may not be quite as obvious. First, LED lights are much more efficient than conventional lighting. In order to discuss this in more detail, it is first important to understand some of the terminology used to describe the efficiency and output of a light. I will discuss a few terms here, but if you would like to learn more, you can refer to this LED terminology page.
Most people are familiar with common power usage terms (i.e. Watts) that are used to describe the amount of energy consumed by an incandescent light bulb (i.e. 60w or 100w bulb). However, what is actually important when comparing a new technology like LEDs is the quantity of light being emitted because the amount of power drawn (Watts) can be dramatically different between two products that produce the same quantity of light. A common measure of light output is Lumens, and a standard comparison would be that a 60w tungsten (traditional) bulb would output around 600-650 Lumens (for more, see this Wikipedia definition).
So, how much energy can be saved? I said earlier that LED lights are much more efficient. One way to compare this is my creating a ratio of the two terms just described - Lumens and Watts - by asking the question "How many Lumens are output for each Watt of energy consumed to generate that light?" For example, the earlier bulb I mentioned consumed 60 Watts of energy and produced approximately 600 Lumens of output. This could be described as 600 Lumens from 60 Watts, or the more standard way to describe this would be 10 Lumens per 1 Watt or 10 lm/w. As a comparison, many LED lights generate upwards of 75-100 or more Lumens per Watt, so, as you can see, LEDs are approximately 7-10x more efficient than this common incandescent bulb. Further, the technology is improving, so this efficiency is increasing every year.
Second, LED lights can save you significant cost on maintenance and upkeep. This is a broad statement and the exact amount of savings will depend on how each individual decides to maintain his or her lights. However, some basic facts are true. For example, LED lights are rated to last as long as 100,000 hours as compared to 7,500 - 20,000 for many traditional lights. Because of this, they will need to be replaced approximately once for every 5-10 changes of the traditional lights. Each change has a cost associated with it that includes the light itself, but often additional hardware such as ballasts, as well as labor, which can be significant, particularly if special equipment such as a ladder truck are required.
Other ways that installing LED light technology can save you money include reducing recycle / disposal fees (because they last so much longer), potential for government and/or utility rebates, and fewer lights because of increased efficiency of lighting.
For examples of different installations, go to this gallery.
Why do LED lights use less energy?
Light Emitting Diodes, or LEDs as they are commonly referred to, use a different technology than traditional, incandescent light bulbs. LEDs, as their name would suggest, emit light. But instead of this happening through the heating of a lighting element such as Tungsten that occurs in an incandescent light, LEDs emit light through the movement of electrons and the resulting release of photons. To learn more, see this Wikipedia entry. What is important about this is that it occurs at an atomic level and requires much less energy for the light to be emitted.
As referenced earlier, another key characteristic of LEDs that contributes to their reduced energy usage is the fact that they do not radiate heat in the same way that incandescent light bulbs do. This not only is more efficient in the production of light, but also, the lack of heat being generated in producing the light means that very little or no energy needs to be consumed to cool the light or the surrounding area when the light is being used. This calculation is typically not included when overall energy savings achieved by an LED is considered, but could be significant if many lights that produce a lot of heat are replaced by LEDs producing relatively very little heat.
Increasingly, LEDs are also being referred to as Solid State Lights or Solid State Lighting, which refers to the type of computer technology that is used to drive the lights. Also, it alludes to the durable nature of the technologies used in these lights.
To learn more about LED terminology, see our terminology page.