Energy Efficient LED Light Bulbs
Green is good, and right now, energy efficient light bulbs are all the rage. With the looming phase-out of old-fashioned incandescent light bulbs in many developed countries, people are faced with choosing between a handful of energy efficient forms of lighting - compact fluorescents (CFL) and light emitting diodes (LED). This article will help you make good decisions when buying residential LED light bulbs.
You have likely already adopted energy efficient compact fluorescents (CFL) as part of your effort to reduce your carbon footprint. While CFLs are energy efficient, they have drawbacks such as mercury and relatively short lifespan. Also, CFLs are not available in sizes that replace track light bulbs, such as MR16 and GU10, and it is unlikely that CFLs will be available in these sizes.
CFLs have made giant inroads over the last couple of years. The low cost and highly energy efficienct CFLs have made them favorites with people replacing incandescent lights. According to the Energy Information Administration, a government agency, 9% of a household's energy costs are related to lighting. People are genuinely concerned with lowering their energy consumption, and lighting is one of the easiest things a person can improve on. With worldwide support from mass-market retailers, governments, and citizens, energy efficient lighting is seeing a new dawn. While CFLs provide a good combination of efficiency and cost, there is an even better option on the horizon - LED light bulbs.
Ultra energy efficient light bulbs - LEDs
LED light bulbs are semiconductors, just like the chips in your computer. These semiconductors emit energy in the form of photons of light. LEDs have come a very long way since they were invented in the 1960s. You have seen LED lamps for decades in the form of indicator lights on electronic products. Now, these LED light bulbs have evolved to the point produce enough light for household and commercial applications. LEDs are extremely energy efficient, and have lifetimes ranging from 50,000 hours to 100,000 hours. LED light bulbs are the perfect complement to your collection energy efficient lighting products.
There are several varieties of residential LED light bulbs on the market. Presently, LEDs best replace track lighting and flood lights, both of which take advantage of the directional nature of LED light. Below are some tips for buying energy efficient LED light bulbs.
• The Basics
You want to find an LED bulb that produces a healthy amount of light, but at the lowest possible power consumption. A good metric that equalizes your search is "lumens per watt". To derive this figure, simply divide the bulb's number of watts into the number of lumens. Right now, a good LED bulb should have at least 40 lumens per watt, but preferably more.
The question is often asked about comparisons between normal light bulbs and LEDs. Here are some examples to guide you:
5-watt, 3 high power CREE LED, MR16 ~ 25-watt MR16 Halogen
5-watt, 3 high power CREE LED, E27 spot ~ 30-watt E27 spot Halogen
6-watt, 165 traditional LEDs, PAR38, ~ 50-watt PAR38 incandescent
• Lifetime of Bulb
Many manufacturers of LED bulbs claim lifetimes of 50,000 hours to 100,000 hours. The lifetime of an LED lamp is generally considered to be the point where the light output has declined to 70% of it's initial output, measured in lumens. So, a 300 lumen LED bulb with a lifespan of 50,000 hours will have 210 lumens at the end of it's lifetime. However, the lifetime of a bulb does not mean it is unusable, only that it's light output has degraded to a certain point. The LED bulb may continue to be useful for several thousand hours past it's stated lifetime. Unlike old-fashioned light bulbs, it is extremely rare for LED light bulbs to simply burn out. Rather, they will gradually fade over time.
As a general rule, you should use warmer light indoors, and whiter light outdoors. A color temperature of 2500-4000 Kelvin works great indoors. You should use a bulb with a color temperature of 5000-7000 Kelvin outdoors, as the whiter light allows your eyes to see better at night.
White light in the 5000-7000 Kelvin range is also excellent for display cases, boutiques, artwork, or other settings where you need excellent color rendition.
• Type of LED lamp
LED light bulbs use one or more tiny semiconductor lamps to produce very focused light. Contrast this with normal light bulbs that generate light in all directions. LED lamps are currently available in two forms: traditional LEDs (typically 5mm), which are smaller, and high power LEDs. Light bulbs using traditional LEDs require a large number of LED lamps to produce sufficient light, whereas high power LED bulbs use one or more lamps to generate light.
In general, the more LEDs, the better the light dispersion. Always get LED bulbs with more than one LED. You will find that single LED bulbs produce a very conspicuous outline, similar to a halo. Unless you enjoy halos across your walls, it's better to buy light bulbs with multiple LEDs.
Here are some common track light and flood light bulb types, and suggestions for the LED arrangements:
For track bulbs such as MR-type and GU-type, try to get bulbs with 3 high power LED lamps (preferably using CREE or Nichia lamps). Avoid buying track bulbs using an array of traditional LED lamps, as these are not as effective as high power lamps.
For flood light bulbs, such as PAR-type, you can find reasonably priced traditional LED arrangements. High-power LED flood lights produce good light, but are also very expensive. In my experience, a PAR bulb using 120 or more traditional LED lamps works just as good, at a fraction of the price.
• Cost and energy savings
LED bulbs have a higher upfront cost, but they pay for themselves several times over their lifetime. Because LEDs have lower power consumption and a very long lifetime, they are very energy efficient. Let's take an example of a $45, 5-watt, 50,000 hour MR16 LED bulb. Let's assume a constant electricity cost of $0.10 per kilowatt hour, and a 0.61 electrical grid CO2 output factor. Compared with a similar $8, 25-watt halogen MR16 bulb, the LED will save $255 and reduce carbon emissions by 1,345 pounds. Not bad for a light bulb.
As energy costs continue to rise, the cost savings and carbon reduction from using LEDs will become far more pronounced.
Buyer beware - LEDs cannot as yet replace general illumination bulbs
Right now, there are plenty of options for LED light bulbs. And that's a bit of a problem. Several sellers of LED bulbs claim their bulbs are powerful enough to replace general illumination bulbs such as incandescent and CFL. This is simply untrue. Many of these "replacement" bulbs cost nearly $100 and use over 10 watts of power. You are much better off using a $3.00, 10-watt CFL for now. However, keep an eye out for LED general illumination bulbs over the next few years, as they will become very competitive with normal light bulbs.
Start today with LEDs
As LED technology rapidly advances, you will see them replace all other forms of light bulbs, including CFLs. If you have track lights or flood lights, you can begin incorporating LED light bulbs right away. Remember, now is the time to take steps to save energy and money. Your wallet and the planet will both thank you.
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"The only mr16 CFL I have seen recommends that you only fit one such unit per transformer. This makes it useless for track systems."
"They actually do make CFLs that fit an mr16 socket."