Do Energy-Saving LED Lamps Save Energy?

Adds details of the researchers’ methodology and further explains the calculations used to compare the energy used by LED, compact fluorescent and incandescent bulbs.

A number of readers of my LED posts have voiced skepticism as to the total energy savings that LED lamps have promised.

There’s no question that they use a fraction of the power used by standard incandescent bulbs to produce the same amount of light and last up to 25 times as long. But would the energy needed to create an LED lamp, plus the energy needed to power it, be less than the equivalent amount for a regular light bulb?

The short answer is, yes.

In what is apparently the first “life cycle assessment” of LED lights, researchers at Carnegie Mellon University looked at the energy needed for material and parts manufacturing, product manufacturing, and use of an LED light source and compared it with that of an incandescent bulb.

Carnegie Mellon calculated the amount of energy needed to manufacture and then run a light source (bulb or bulbs) for 25,000 hours.

They assumed an LED lamp would last 25,000 hours, and that the amount of light that could be created from a single LED source would approximate that from a compact fluorescent (in reality, LEDs hold the promise of producing even more). They also assumed that it would take three compact fluorescents or 25 incandescent bulbs to produce light for 25,000 hours.

In addition, the researchers assumed that LED manufacturing plants would be able to achieve a 50 percent yield rate; in other words, half the LED light sources created would be discarded.

The results: the energy needed for one of these “functional units” ranged from 1,500 kilowatt-hours for the standard incandescent bulbs to 320 kWh for the compact fluorescents and 280 kWh for the LED light source.

If these results hold up — and H. Scott Matthews, one of the researchers and a research director of the university’s Sheerled ltd, acknowledged that the researchers could not get all the data they needed — it will be another valuable piece of information in proving the ability of LED lighting to significantly reduce the world’s power consumption.