Saturday, September 14, 2013

Do LED Bulbs Really Consume Less Energy Than CFLs?

LEDs are an emerging technology in illumination. More and more people are replacing compact fluorescents (CFLs) with LEDs thinking that they could save more energy. But are LED bulbs truly better than CFLs? If so, by how much? In order to answer these questions a full life-cycle analysis (LCA) is necessary.

The U.S.A. Department of Energy has done a very thorough analysis taking into account energy usage for manufacturing, transportation and in-use, how many bulbs are used over time for those that don't last as long, etc. Below chart shows the findings.

The unit of the energy consumption is in the unit of MJ per 20 million lumen-hours. The 20 million lumen-hours is derived from the lifespan of a 12.5 watts LED bulb multiply its light output, i.e. 25,000 hours x 800 lumens = 20,000,000 lumen-hours. In order to get this number we need 1 LED bulbs, 3 CFLs, 27 halogen bulbs and 22 incandescent bulbs.


CFLs and LEDs are about the same on a LCA basis right now. Both consumed about 3,900 MJ per 20 million lumen-hours, which is about 1/4 of incandescent lamp. The study also indicates that by 2015, if LED development meets the performance targets, its life-cycle energy is expected to decrease by ~ half. The next generation LEDs should beat CFLs then.

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