LED Guide - How to Buy LED Light Bulbs

Light emitting diodes, commonly known as LEDs, are becoming more and more widespread in all types of electronics. Their current uses range from small LED flashlights to street signal lights, laptop computers, and giant video billboards.

What a lot of people don't know is that they are starting to find their use in a more common type of lighting application that can be found in nearly every home or office around the world. I am, of course, talking about LED light bulbs.

The fact that you are reading this guide shows that although the idea of using LEDs to replace traditional lighting is starting to become more well known as a greener alternative to energy-efficient lighting (as currently compact fuorescent bulbs are the most widely known), but there are still a lot of people that do not know enough to make an informed decision about how and when to purchase LED light bulbs.

This guide was written as a complete buying guide to give you almost everything you need to know to make an informed decision about buying LED light bulbs and to help you determine whether LED lighting is right for you. This will be a constantly changing document as LED lighting technology is changing so quickly so keep checking back for updates!

Introduction

Now the pace at which technology is progressing for LEDs right now is astounding as you hear about new developments in LED lighting almost every single week. One of the big pushes for this is not only a significant savings on their electric bill (although that is one of the best reasons to switch), but rather the realization that we all need to rally together and do our part to save the environment. Being green is not just about being "in style" anymore, it has become a practical business model that can help the planet as well as our pocketbooks. People are becoming aware of global warming and becoming more environmentally conscious overall, and are looking for ways to cut their energy consumption. What easier way is there than simply changing a light bulb?

Compact fluorescent light bulbs (also known as CFLs) and LED light bulbs are currently the best alternatives if you want to decrease your energy expenditure in regards to lighting. Unfortunately, LED light bulbs can be more difficult to find and the initial cost can be many times more than a normal incandescent or even CFL. This guide will help you with that decision by providing :

• a simple understanding of how LED bulbs work,
• what applications they will work best in, and
• overview of how LED light bulbs compare in the lighting industry as a whole.
  

I hope that after reading this, you will be able to see the benefits that LED light bulbs have over other traditional lighting solutions.

Compact Fluorescent Bulbs - What You Didn't Know

Compact Fluorescent or CFL bulbs have been lauded in the past few years by the various media outlets as the new way to save energy as they are much more efficient (i.e. use less energy for the same amount of light) than standard incandescent light bulbs. What they don't mention a lot of the time are some of the things that you have to watch out for. The largest problem that CFLs have, that no one type of standard lighting (including LEDs) has is that....

CFLs contain mercury.

CFL bulbs contain small amounts of mercury which is toxic to individuals, especially those that are still developing, such as children and pregnant women. This is an inherent part of the technology so you will never get a CFL bulb that doesn't contain mercury. Most CFLs contain about 3-5mg of mercury. Here's some excerpts from Wikipedias article on mercury:

"A study has shown that acute exposure (4-8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m3 resulted in chest pain, dyspnea, cough, hemoptysis, impairment of pulmonary function, and evidence of interstitial pneumonitis.[37]"

"Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency."

Now what should you do if you accidentally break a CFL bulb? Here's some cleanup procedure excerpts taken from the Environmental Protection Agency's website :

• "Have people and pets leave the room, and don't let anyone walk through the breakage area on their way out."
• "Open a window and leave the room for 15 minutes or more."
• "Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder."
• "If vacuuming is needed after all visible materials are removed, - Remove the vacuum bag and put the bag or vacuum debris in a sealed plastic bag."
• "The next several times you vacuum, shut off the central forced-air heating/air conditioning system and open a window before vacuuming."
• "If clothing or bedding materials come in direct contact with broken glass or mercury-containing powder from inside the bulb that may stick to the fabric, the clothing or bedding should be thrown away."
  
  

So not only is it a pain to clean up, but it is not something that you want to have ever happen, even once. Supporters of CFLs claim that the bulbs are not fragile as are less likely to break, thus reducing the chance of needing such intricate procedures to clean them up. The fact that they are in the house or office, means that there will always be that possibility. As recently as February of 2008, the state of Maine did a study on handling broken CFLs and the precautions you need to take when disposing of them. You can read the study here.

Other problems that CFLs have include:

They are less efficient than LEDs - CFLs, despite their efficiency, are still only about half as efficient than LEDs. A 10W LED bulb gives about the same amount of light as a 20W CFL bulb.

Bi-pin LED bulbs

They have an undesirable form factor - CFL bulbs aren't exactly appealing to the eye and currently can't replace bi-pin halogen bulbs (MR16 and GU10) typically used in many track lighting applications.

They have a shorter lifespan - The life of a CFL is significantly shorter if it is only turned on for a few minutes at a time: In the case of a 5-minute on/off cycle the lifespan of a CFL can be up to 85% shorter, reducing its lifespan to the level of an incandescent lamp. The US Energy Star program says to leave them on at least 15 minutes at a time to mitigate this problem. (LEDs can be cycled on and off with no problem and work better in cold temperatures.)

Warm Up Time - CFLs takes a perceptible time to achieve full brightness, and can take much longer in very cold temperatures.

Not Fully Dimmable - Dimmable CFL have emerged in the past year, but there have been reports of buzzing and color shifting while dimming as well as a limited range of dimmability. Most LED bulbs are not dimmable at the moment, but the ones that are, are fully dimmable and do not buzz. Keep a lookout for dimmable LED bulbs that we've found.

LED Light Bulb Buying Guide

How to Determine If LEDs Are Right For You?

How much will you spend on the bulbs?

Consider the cost savings and other benefits -

1. Cost - LEDs cost more initially, and there is no doubt that they save you a lot of money in the long run because they last longer and use less energy. Money savings is from using 80% less energy and not having to buy about 25 traditional flood light bulbs. Depending on your state, savings and time for the bulb to pay for itself can vary. Over 50,000 hour for a typical 7W LED Flood Light replacement bulb (MSRP $79.99) that replaces a 50W Incandescent Flood at 8 hours usage per day:

• If you live in Idaho where electricity is the cheapest in the country at 6.3 cents/kWh
  You save: $180.46 and the bulb pays for itself in 7.6 years.
• In California where the cost of electricity is 14.35 cents/kWh:
  You save: $353.54 and the bulb pays for itself in 3.9 years
• In Hawaii where the cost of electricity is a whopping 28.27 cents/kWh:
  You save: $652.82 and the bulb pays for itself in 2.1 years!
  
  

Keep in mind, at 8 hours a day, these bulbs will last about 17 years before they need replacement. You can see the savings really vary so go here to see how your state compares: http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_b.html

If the savings is not as quick as you'd like, there are a few other factors to consider as well that can strengthen the case for switching to LEDs:

A pain to replace...

2. Convenience - If you have bulbs in hard to reach places, by replacing them with LED, you dont have to worry about replacing them for a long time. No more driving to the store, buying them, coming back, taking out the ladder, and disposing of old bulbs. In places where you have a lot of bulbs, the time saved can really add up.

3. Heat If you have a lot of flood lights in a small area, it can really heat up a room significantly. LEDs give off very little heat in comparison. By talking to energy engineers (in California), a good rule of thumb for every kwH of electricity reduced by using LEDs instead of incandescent, you can keep your thermostat higher and reduce your A/C costs by about 20%. I.e. if you save 1000 kWh of electricity per year, you can factor in about an extra 200 kWhs in reduced air conditioning costs as well. Besides the additional money savings, by switching to LED's, your room will be much cooler.

Do you need to spend extra to cool your home?

4. Conscience Do you feel guilty about leaving the light on? Do you have kids that ALWAYS leave the light on? With LEDs they cost a couple of dollars to run a year so you can feel better about having your lights on. A 7W LED bulb run for 8 hours a day for 365 days in California would use about $2.86 a year in electricity compared to $20.44 for a 50W incandescent flood.

LED Bulbs What You Need to Know

Bulb Lifetime

Initially when LED bulbs came out with no standards, manufacturers would claim lifetimes of 100,000 hours with no real testing. Since then the standard has been to scale back to 50,000 hours so as not to over-state claims. (Beware of bulbs that are rated at 100,000 hours unless they state specifically WHY they are rated at so high manufacturing process, heat sink materials etc., I would be wary of trusting this rating). 

As of May 2009, Many of the manufacturers that we've spoken to, producing their 3rd generation LED bulbs are now starting to be more conservative and rating their bulbs at 35,000 hours, having gotten test results back from 1-2 years of testing. Rated at 35,000 hours, you can rest assured the manufacturer is not overstating their claims. Anything more than 50,000 hours...buyer beware.

The lifetime of an LED lamp is generally considered to be the point where the light output has declined to 70% of its 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 its lifetime. However, the lifetime of a bulb does not mean it is unusable, only that its light output has degraded to a certain point. The LED bulb may continue to be useful for several thousand hours past its stated lifetime. Unlike old-fashioned light bulbs, it is extremely rare for an LED light to simply burn out. Rather, it will gradually fade over time.

Color Temperature

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.

Fun Fact: The color temperature scale was created by heating a piece of iron and observing the color that it changes as it heated up. As it got hotter, the color changed. So at 2000 degrees, it was a red-orange color and as it got hotter, the color changed from red to white to blue being the hottest at 10,000 degrees K.

How to compare the quality of different bulbs -

There are quite a few websites online that you can buy LED bulbs. The problem is "how do you compare one bulb to another?" A quick way to do is to calculate the lumens/watt, or in laymans terms, the total amount of light you get for the amount of electricity you put in. This is done by simply dividing the bulbs wattage by the stated number of lumens.

Anything over 50 lumens/watt is good at the moment. 75 lumens/watt is very good while 100 lumens/watt is excellent. We will be discussing the concept of lumens in a more detailed article in the near future titled: Lumens why you cant use them to compare LEDs to traditional bulbs.

One thing to keep in mind: A halogen flood bulb is more efficient than an incandescent flood and usually costs a little more. Typically for a halogen you get about 1.5x more light for the same wattage. i.e. a 20W halogen bulb gives about the same amount of light as a 30-35W incandescent flood. You can tell if its an incandescent or halogen by reading the packaging of the bulb.

A quick comparison as well to normal light bulbs is as follows:

• 3W High Power LED Bulb Comparable amount of light as a 30W incandescent flood.
• 7W High Power LED Bulb Comparable amount of light to a 50W incandescent flood.
• 12W High Power LED Bulb Comparable amount of light to an 85W incandescent flood.

Keep in mind this is just a general comparison - some bulbs may be rated as brighter or dimmer than this. LED bulbs typically have their LED chip or die bought from one place, then assembled elsewhere where labor is cheaper. There are a number of "well known" LED chip manufacturers at the moment. If they're not in this list, chances are they are a smaller company, and are probably less reliable.

From the ones we have experience in testing, and have heard of from the hundreds of manufacturers we've dealt with, the bigger names are:

Cree (USA), Luxeon (USA), Nichia (Japan), Edison (Taiwan), Seoul Semiconductor( Taiwan) and Epistar (Taiwan)

Here is a typical comparison of lumens direct from a manufacturer in China for a 7W LED bulb using different dies/chips:

You can see that Cree is by far the brightest. However, there are multiple factors, besides the LED chip that determine the brightness of an LED bulb including the power supply and optics (the lens or lenses that are used to diffuse the light).

One surpising example we've seen and tested is one bulb that used 9 x 3W Cree LEDs (27 Watts), while another used 6 x 3W Epistar LED(18 Watts). The lens being used in the Cree LED bulb was poor, so the light pattern was uneven and the bulb was about 30% dimmer than the the Epistar bulb, even though it used much more energy.

Also notice that Warm White is always less bright than Cool White. This is because in simple terms, in order to get the warm white color, the LED is coated with yellow phosphor to make it "warmer" and thus reduces the light output. Cool White LED's have "less" of a coating.

Beam Angles

Typically you'll see bulbs in the 30 to 70 degree range. These are spotlights and will give a much more focused light than traditional incandescent flood lights. The best way to tell is to see an actual picture of the bulb in action since this measurement can vary widely between manufacturers. Even though youll hear comparable to a 50W flood, the LED light will in the majority of cases be more focused than a floodlight. Again the best way to tell is if the site shows you a side-by-side comparison.

If youre looking for a more dispersed light like a traditional bulb, look for a 120 degree beam angle or larger.

Warranty

If you're going to spend $30-100 dollars on an LED bulb make sure your investment is protected. Sure you can buy off auction sites and get them on the cheap with no warranty, and a knockoff LED chip or you can spend the money and get a good bulb with a solid warranty. Dont settle for anything less than a two year warranty since the bulbs should last at least 4 years at 24 hours usage per day (35,000 hours).

Start Using LEDs Now!

LEDs arent a good alternative for all bulbs in your home. Depending on your situation, they make sense in some places more than others. The more people who adopt LEDs, the quicker prices will come down. Theres no doubt that as prices come down, and efficiency/light output of the bulbs increase, in a couple of years every light bulb in the world will be an LED Light bulb and CFLs and incandescent will be a thing of the past. The initial investment may be a little hard to swallow, but in the long run, youll be doing your part for the environment and your wallet and making the world a cleaner, greener, cooler place to live one bulb at a time for generations to come.

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For a wide-range of LED light bulbs, that come with a two-year warranty, from flood lights to globes with picture comparisons and detailed payback periods by state, check out our online store at: http://www.eternaleds.com/.

Keep a lookout for our next article:

Lumens why you cant use them to compare LEDs to traditional bulbs

Jeff Chan
Eternaleds Inc.

Last Updated 5/27/09