Buying Light Bulbs

We typically have been buying light bulbs based on how much energy they consume (Watts), regardless of light emitted (Lumens). All that began to change with the advent of different types of light bulbs, such as CFL, halogen, LED, etc., since they consume different amounts of energy to produce the same amount of light.

Lumens measure how much light you are getting from a bulb, regardless of type and regardless of energy consumed. This equalizes all bulbs and types for comparison. More lumens means brighter light.

Another measurement that is not well understood is Kelvin. It is a scale of measurement for the color a light produces. The higher the Kelvin (K) number, the cooler the light appears. Most bulbs will be in the 2,500K to 6,500K range, with 2,500 being the warmest and 6,500 the coolest. Kelvin is usually ignored except for specific lighting circumstances. The 2,700K to 3,000K range is warm and inviting, 3,500K casts a neutral light, 4,100K casts a cool and bright light, 5,500K to 6,500K range is closest to daylight.

To compare brightness of typical old style bulbs, here are a few examples:
Replace a 100-watt incandescent bulb with a bulb that gives you about 1600 lumens,
Replace a 75W bulb with a bulb that gives you about 1100 lumens,
Replace a 60W bulb with a bulb that gives you about 800 lumens,
Replace a 40W bulb with a bulb that gives you about 450 lumens.

Sixty watt bulbs used to be the standard as they offered the best compromise of minimum required light and cheaper cost. Now that energy cost has been so greatly reduced, 1100 lumen lights are becoming the standard minimum. Brighter lights make it easier to see and make everything look better, especially when trying to sell your house.

LED, Lumen, CFL, and CRI

We are now faced with many choices for light bulbs. Prices vary widely for not much difference in light. Here a few things to know about the choices.

First, lumens are the new watts. Watts are power and lumens are light. An old incandescent 60 watts is about 800 lumens of light. The wattage does not matter and most of the comparisons regarding electricity costs are measured over years, so not very consequential in a monthly or annual budget. A 60W incandescent lamp may push 800 lumens, while a CFL only needs 15W and an LED only needs 10W to produce the same lumens. (A 10W incandescent is a night light.) The thing to remember is how bright you want your light to be. Look at lumens below to get the correct amount of light from your new bulbs.

incandescent bulb
watts - lumens
60 - 800
75 - 1,100
100 - 1,600
150 - 2,600

Heat might not seem important, but with a number of lights burning, it adds up, especially during the summer. One heat test - halogen bulb, a type of incandescent bulb, measured 327 degrees. A Cree LED downlight was measured 107 degrees and a Philips Par38 CFL measured 167 degrees. LEDs produce 3.4 btu's/hour, compared to 85 for incandescent bulbs.

Bugs don't fly toward many LEDs, because bugs are attracted to ultraviolet light and most LEDs do not give off this type of light.

LED are rated to last 50,000 hours, while CFLs are rated for 10,000 hours and incandescents are rated for about 1,000 hours.

LED bulbs turn on as quickly as incandescent bulbs and faster than CFLs. LEDs produce roughly the same amount of useful light, but much of that light is focused in one direction. LEDs typically shine up, rather than in all directions like incandescent bulbs. Newer LEDs can be omnidirectional, look for that word on the package.

Some LEDs do not dim well and tend to buzz or sputter when the dimming is at half. Check the package to make sure the bulb will work with a dimmer.

A new term to further confuse us is CRI, because of the number of different light types. It did not make any difference in the past as all lights were the same. CRI is color rendering index. The higher the CRI, the better the color rendering ability. Light sources with a CRI of 90 or higher are excellent at color rendering and should be used for tasks requiring the most accurate color discrimination. CRI is independent of color temperature, but I won't even go there. Too much information.

When considering lighting, I usually think of CFL as meaning 'crap for light'. They take longer to turn on (it typically takes 30 seconds to 3 minutes to complete), need more energy to turn on, contain mercury, may leak UV radiation, do not work well in cold conditions, produce artificial fluorescent color, and are less efficient than LEDs.

Although initial price is still much higher, the price of LEDs is coming down quickly. LEDs are down to $4.97 at Home Depot, a far cry from the old $20 they used to cost. Bottom Line, let your old bulbs burn out before you rush out to buy new "energy savers" the price will likely be cheaper when you are ready to replace. Also, higher lumens are brighter and higher CRI provides better color discrimination.

Another Ten Interesting Facts About Humans

1. Laughing lowers levels of stress hormones and strengthens the immune system. Six-year-olds laugh an average of 300 times a day. Adults only laugh 15 to 100 times a day. Am glad I have not grown up.
   
2. Intelligent people have more zinc and copper in their hair.
3. The human heart creates enough pressure while pumping to squirt blood 30 feet.
4. The brain operates on the same amount of power as 10-watt light bulb. Your brain generates as much energy as a small light bulb even when you are sleeping.
5. The brain is much more active at night than during the day.
6. The brain itself cannot feel pain. The brain might be the pain center when you cut your finger or burn yourself, but the brain itself does not have pain receptors.
7. The fastest growing nail is on the middle finger and the nail on the middle finger of your dominant hand will grow the fastest of all. Nail growth is related to the length of the finger, with the longest fingers growing nails the fastest and shortest the slowest.
8. The lifespan of a human hair is 3 to 7 years on average.
9. Human hair is virtually indestructible. Aside from it’s flammability, human hair decays at such a slow rate that it is practically non-disintegrative. Hair cannot be destroyed by cold, change of climate, water, or other natural forces and it is resistant to many kinds of acids and corrosive chemicals.
10. The acid in your stomach is strong enough to dissolve razorblades. Hydrochloric acid, the type found in your stomach, is not only good at dissolving pizza, but can also eat through many types of metal.

New GE Bulb

First we get the hundred dollar bulb, now we get an over-engineered bulb that requires built in cooling. GE just announced a new LED light bulb replacement for the 100 watt incandescent that uses pulses of air to keep cool. The design comes just as the 100 watt incandescent bulb phase-out is this year, 2012. 

If common bulbs cost a hundred dollars, need to be cooled, or contain mercury they have other deficiencies beside cost. This would be the same as building an iPad that cost five thousand dollars and needs continuous water cooling. GE and Philips must be designing these bulbs in Washington DC. Thomas Edison is likely crying in his grave at the politicians who caused this.

CFL Light Bulb Facts

CFLs burn out rapidly when they’re not allowed to rest at least 15 minutes between being cycled off and on. They overheat and fail if they are used in recessed ceiling canisters

CFL floodlights in outdoor motion-sensor systems is bad because of how fast the bulbs expire when they have to flick on and off so quickly. CFLs contain mercury, enough that the Environmental Protection Agency’s cleanup instructions for a broken bulb run three pages and start with a warning to open windows and evacuate people and pets.