CFL vs. Incandescent Light Bulbs

The common everyday incandescent light bulbs that most of us still use are very inefficient. A 100 watt incandescent light bulb is 2.6% efficient. That means that out of the 100 watts of energy that I put into the bulb only 2.6 watts get used to create light, the rest just gets burned up in heat.

CFL or compact fluorescent lamps are similar to large tub fluorescent lights that are used in commercial buildings. The long tube has been twisted around to make more of light bulb shape. These light bulbs are not as simple to make as incandescent but amount to a great deal of energy savings. A CFL is between 9-11% efficient, that’s four times the energy savings over an incandescent. CFLs are also rated to have almost 10 times longer life!

Cost Comparisons between CFLs and Incandescent

25-Watt Compact Fluorescent 100-Watt Incandescent
Cost of Lamps $3.40 $0.60
Lamp Life 1,667 days (4.5 years) 167 days
Annual Energy Cost $6 $25
Lamps Replaced in 4.5 years 0 10
Total Cost $29 $134
Savings Over Lamp Life $105 0

Quick Tip

Don’t use CFL in place where you constantly turn the light on and off, and leave on only a short duration of time. Constantly turning on and off a CFL will greatly diminish its life. So areas like closets and hallways may not be the best place for a CFL


CFL do contain mercury just like any other fluorescent light and need to be disposed of properly. Store like Home Depot and IKEA have a drop off box and will recycle them for you. You can also check out your municipal center for recycling programs in your area that can properly hand mercury.

Additional Links

How Compact Fluorescents Compare with Incandescents

The Best Compact Fluorescent Light Bulbs: PM Lab Test

Incandescent light bulb

Compact fluorescent lamp

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