Which Is Greener: LED’s or CFL’s?

Author’s Note: For The Chicago Tribune, I answered a series of readers’ questions about living a greener, more sustainable life. This Trib reader wrote in to find out if LED lights were more efficient than CFL’s. Here’s what I dug up.

There’s no question that LED’s have a bright future, but Compact Fluorescent Lightbulbs (CFL’s) remain your most accessible, environmentally responsible lighting option for the home. Which is not to say the CFL is perfect. It is vastly more efficient than an incandescent bulb, but each CFL contains about 5 milligrams of environmentally harmful mercury-about equivalent to the size of a ballpoint pen’s tip, by ENERGY STAR’s calculations.

Not only are LED’s mercury-free, their long lifespan makes the Energizer Bunny seem like a quitter.Unlike traditional light sources-which throw off relatively consistent light and then, poof, burn out–LED’s get dimmer over time. Analysts recommend that the LED’s last rites be administered when they emit 70% of initial light output. Using that measurement, the Department of Energy, Energy Efficiency and Renewable Energy (DOE, EERE) calculates that the highest-quality white LED’s have a useful life of around 35,000 hours.

Some context: You could turn on a high-quality, white LED and forget about it for four years, when it would finally need replacing. Compare that to your garden-variety, 75-watt incandescent bulb, which throws out 1,000 lumens for about a buck, according to the DOE. That dollar bulb-which converts only about 5% of the electricity it consumes into light-will expire in about 1,000 hours. Comparable CFL’s-which are five times more efficient than incandescent bulbs-cost less than $5 and last 10,000 hours.

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