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.