Q&A: How much can I save by replacing incandescent bulbs with CFLs?

Consumer Reports News: March 29, 2010 11:13 AM

Compact fluorescent lightbulbs are touted as big money savers. But since they cost so much more than incandescent bulbs, can I really save money by switching to CFLs?

In a world filled with greenwashing, CFLs, like those featured in our latest review of compact fluorescent lightbulbs, are among the energy-saving products that will actually save you some real money.

Replace CFLs to Save Money
The savings from CFLs can really stack up.
By replacing a 60-watt incandescent bulb—the most common household bulb—with a spiral-type 13-watt CFL that produces an equivalent amount of light, you could save more than $57 over the life of the CFL. Your savings will vary depending on the cost of the 13-watt CFL and your electricity rate. These calculations are based on the national average rate for electricity, which now stands at about 11.5 cents per kilowatt hour and ranges from a low of 7 cents in North Dakota to a high of more than 26 cents in Hawaii.

Several of the best Energy Star-qualified spiral CFLs we tested cost $1.50 each, and we found they last about 10,000 hours. An incandescent bulb costs 50 cents and lasts about 1,000 hours. That means you'd need to use 10 incandescents for every CFL. Based on those prices and using 11.5 cents per kWh, here's how we arrived at the per-bulb savings:

$16.45 to buy and operate a CFL for 10,000 hours:
13 watts x 10,000 hours = 130 kWh
130 kWh x 11.5 cents per kWh of electricity = $14.95
$14.95 + $1.50 for bulb = $16.45

$74 to buy and operate 10 60-watt Incandescent bulbs for 10,000 hours
60 watts x 10,000 hours = 600 kWh
600 kWh x 11.5 cents per kWh = $69
$69 + $5 for 10 bulbs = $74

Savings: $74-$16.45 = $57.55

Based on the current national average electricity price, higher-wattage bulbs will cost $1.15 more to operate for every additional watt. So a 19-watt CFL will cost $21.85 over its life, and 10 75-watt incandescents will cost $86.25. (These figures don't include cost of bulbs.)

If a bulb doesn't last as long as its manufacturer claims, you'll obviously need to replace it more frequently, which will eat into your savings. So we recommend you buy only Energy Star-qualified bulbs, which are supposed to meet the U.S. Department of Energy's higher standards. Also remember that the longer a bulb lasts, the less frequently you'll have to replace it.

To find the right type and best bulbs for your uses at home, use our how to choose advice and refer to our ratings of spiral, indoor and outdoor flood/reflector, and porch/post covered CFLs (available to subscribers).

Kimberly Janeway

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