Light bulbs are changing.

Federal rules taking effect Jan. 1 ban the manufacture of incandescent bulbs using 40 watts of power or more, the third phase of energy efficiency legislation passed in 2007.

The intent of the law is to push consumers toward more energy-efficient lighting technology than the incandescent light bulb – which has helped beat back the night for more than a century, but expends most of its energy producing heat rather than light.

Compact fluorescent lamps — those spiraling tubes that some consumers may associate with harsh light and delayed start-up — cost more than incandescents but last longer and use 75 percent less energy.

Halogen incandescent bulbs are more energy-efficient than older ones, but less efficient than CFLs, which are emerging as the most common alternative as higher-wattage incandescents fade out.

And retailers say their quality has improved significantly.

“If you bought a CFL bulb three years ago, you might not know how good the technology is now,” said Mark Smith, a Houston-based director of operations for retail chain Batteries Plus Bulbs.

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