If Nick Holonyak, Jr.’s name isn’t as familiar to you as Thomas Edison’s, it’s understandable but unfortunate. Because while most anyone can tell you that Edison invented the incandescent electric light bulb, few people know that it was Holonyak who revolutionized that concept in 1962 with his invention of the first visible-spectrum Light Emitting Diode, or LED. Initially, LEDs were mostly used for numerical displays in devices like alarm clocks, calculators and watches. But as LED technology advanced and manufacturing costs declined, the potential for LEDs as a source of large-scale energy efficient lighting began to take off.
LEDs operate when an electric current passes through a semiconductor, bringing together positive and negative charges that release energy in the form of light. We could give you all the technical jargon about how the electrons in the current recombine to release photons that create electroluminescence, but understanding the science of how LEDs work isn’t as important as understanding why you should replace your existing lighting system with energy efficient LEDs.
Let’s begin, though, by merging the how and the why to compare LEDs with other types of lighting systems. In an incandescent bulb, electric current is used to heat a wire filament to a temperature high enough to make the filament glow and produce light. In fluorescent lighting, a small bit of mercury inside the tube or bulb is activated by the current and converted into a gas, which in turn activates a coating inside the tube or bulb to produce light. The major drawbacks of the incandescent system are the large amounts of electricity needed to produce the desired amount of light and the waste heat that’s generated from making the filament hot enough to glow. Although fluorescents can produce the same amount of brightness as an incandescent with significantly less electricity and less waste heat, the mercury inside the tube or bulb can create environmental issues with breakage or disposal, and the light from fluorescents tends to be harsher and less natural than other forms of lighting. In comparison, LEDs are the ultimate green energy solution because they require little electricity, produce virtually no waste heat and don’t contain harmful elements.
Any discussion of the economic advantages of LEDs is going to start with electricity, since that’s the biggest expense related to lighting. LED lighting uses about 75% less electricity than incandescent, and about 30% less than fluorescent. This means that you’d be saving $750 on your electric bill for every $1,000 you’re now spending to operate incandescent lighting and $300 for every $1,000 it’s costing you to run your fluorescents. That’s a significant saving for any business, especially one which uses a lot of indoor and/or outdoor lighting. Those savings can be magnified if your business is subject to a demand charge on your electric bill (a charge in addition to the number of kilowatt-hours you use that reflects the moment in time during a billing cycle when your electric use is the highest), since reducing your electric demand for lighting at times when you need to operate other equipment – like air conditioning, refrigeration or machinery – will help to lower your demand charge as well.
The other major economic advantage of LEDs is their long life. Since LEDs need to be replaced much less often than other forms of lighting, capital costs and maintenance expenses for your lighting system can both be significantly reduced. A typical incandescent bulb can be expected to last about 1,000 hours, while a comparable fluorescent fixture has a lifespan of about 10,000 hours. By comparison, LEDs can provide light for 25,000 hours (some LED manufacturers now say that their lights will last for 50,000 hours, but since it would take nearly six years of 24/7/365 operation to prove that claim, we’ll offer the more conservative estimate). While it’s true that LEDs cost more than those other forms of lighting, their extended lifespan more than offsets the higher initial cost since you’ll be buying fewer LEDs over time.
We know what you’re thinking at this point: “LEDs may save me money, but am I going to be sacrificing quality in return for those savings?” And here’s our answer: Absolutely not! The brightness, warmth and quality of the light produced by LEDs is comparable – if not better than – what you’ll see from other forms of lighting.
Brightness is measured in lumens, so the number of lumens – not watts – is the determining factor in deciding how much light is needed in a certain area. The amount of electricity needed to produce a similar number of lumens varies greatly among lighting systems. For example, a 75-watt incandescent bulb will generally produce 1,000 lumens; but the same level of brightness can also be achieved with an 18-watt fluorescent or a 12-watt LED. Put another way, an LED will give you about 83 lumens per watt, compared to 55 per watt for fluorescents and only 13 per watt for incandescent. Choosing the right amount of brightness for your business’ lighting needs – and for each particular application within your business – is an important decision, since brightness impacts everything from safety considerations to a healthy work environment.
The color temperature of lighting – what some people might refer to as “warmth” – is also a factor in choosing a lighting system. Color temperature is measured in degrees on what’s known as the Kelvin scale. The lower end of the scale (from 1,800 to 2,800 degrees) includes yellowish light from candles and incandescent bulbs. Light gets whiter toward the middle of the scale, with fluorescents coming in at around 4,500 degrees. Sunlight hits the scale at 5,600, with the light getting bluer above that number. LEDs can be purchased in a wide range of options – generally from 2,700 to 6,500 degrees – giving you greater flexibility in choosing the level of “warmth” that’s perfect for your specific needs.
In addition to light temperature, light color is important to businesses that want to bring out the true natural colors of the items being displayed and sold – like the red of an apple in a food market or the blue of a dress in a clothing store. Several metrics have been developed to measure the ability of a lighting source to truly reveal the colors of the items they’re illuminating as compared with natural daylight. The most widely used metric is the Color Rendering Index, or CRI, which runs from 1 to 100 with 100 being the closest to natural daylight. LEDs generally fall into the 80-95 range on the CRI while basic fluorescent lighting comes in at around 50 (more advanced forms of fluorescents will get higher scores), so LEDs are superior when it comes to color accuracy.
LEDs have other advantages, too. They can operate in extremely hot or cold conditions, so they’re well suited for outside lighting. They have great design features that offer flexibility and scalability in how you use them. They focus their light within a narrow range to create greater efficiency than incandescent or fluorescent bulbs that throw off light in all directions. In short, LED lighting systems are superior to anything else on the market.
An LED lighting retrofit should be part of a “whole building approach” to energy efficiency that includes upgrades to your heating, air conditioning, hot water and other mechanical equipment. But even as a stand-alone improvement, an LED retrofit offers one of the fastest paybacks of any green energy solution. The energy efficiency experts at Ecology Action can guide you through the process and see if you’re eligible for utility or government rebates.
So while we’re not anticipating that Southern California Edison will be changing its name to Southern California Holonyak anytime soon, we are expecting that Mr. Holonyak’s invention will soon overtake Mr. Edison’s as the preferred form of lighting.