Guest post by Jim Brodrick, U.S. Department of Energy
Although LED lighting has many potential advantages, energy savings is the one that attracts the most attention. But the energy savings during the course of a product’s lifetime only tell part of the story. To gauge a product’s full impact – not only in terms of energy consumption, but also on the environment – its whole life cycle has to be considered, from cradle to grave.
Recognizing this, DOE has launched a three-part effort to assess the total life-cycle impact of LED screw-based replacement lamps, comparing them with conventional lighting technologies. A report on Part 1, Review of the Life-Cycle Energy Consumption of Incandescent, Compact Fluorescent, and LED Lamps, was published this week. It’s based on existing life-cycle assessment literature of lighting products (including academic publications as well as manufacturer and independent research reports) and looks at three life-cycle phases – manufacturing, transportation (from factory to retailer), and use – comparing the energy consumed and considering how that consumption might change in the future for LED lamps.
The second part of the project should be completed this summer and involves a life-cycle environmental analysis of the direct and indirect material and process inputs to make the LED products. The third and final part of the life-cycle effort, which is expected to be finished by October, involves taking the products apart and chemically testing them using existing testing standards, to determine what materials they contain, and in what concentrations. A final report will combine the results of all three analyses to provide a basis for comparing the full environmental tradeoffs between LED and conventional lighting sources.
So what did we learn from Part 1 of the project? Well, for one thing, the average life-cycle energy consumption of LED lamps and CFLs is similar, and is about one-fourth the consumption of incandescent lamps. But looking further down the road, if LED lamps meet their performance targets by 2015, their life-cycle energy is expected to decrease by approximately one-half, giving them a distinct advantage over CFLs, which are at a more advanced stage of development in terms of energy performance and thus not likely to improve as much as LEDs.
As might be expected, the “use” phase of all three types of lamps dominates the results, accounting for 90 percent of total life-cycle energy, on average. This is followed by the manufacturing and transport phases respectively, with transport representing less than one percent of the life-cycle energy for all lamp types. Not all of the literature is in agreement about the energy consumption of LED package manufacturing, which various sources estimate at anywhere from 0.1 percent to 27 percent of life-cycle energy use, with the average – estimated after considering the strengths and weaknesses of the various approaches – being 7 percent.
The Part 1 study only considers LED replacement lamps, although integrated luminaires designed specifically for SSL can take much better advantage of the technology and thus produce efficacies beyond those of even the best-in-class LED replacements. Parts 2 and 3 will address both replacement lamps and integrated luminaires. Part 1 confirms that the cradle-to-grave energy performance of an LED is roughly equivalent to current CFLs, with most of the energy consumption occurring during the operation of the LED. Future work will focus on the uncertainty associated with the manufacturing process and environmental assessment of LEDs.
