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A tale of two tests: why Energy Star LED light bulbs are a rare breed

Just over a week ago we reported that Philips' 22 W LED light bulb, designed as a like-for-like replacement of a 100-W incandescent light bulb, was the first LED bulb of its type to receive the stamp of approval from Energy Star. But looking at the Energy Star requirements reported by Philips in its press release, it seemed a little strange that Philips' product is the only one to have been certified – given that products long on the market appear, at face value, to meet those requirements. Since then, Gizmag has spoken to LED light bulb makers Switch Lighting and other industry players to find out why they're apparently playing catch-up.

"Those who do not remember the past …"

It turns out the reason is simple, but has a little bit of back-story attached. Unlike Energy Star certification for other types of appliances, an Energy Star-certified LED light bulb signifies reliability and performance as well as energy-saving performance. The reason for the difference is down to the problems faced by ordinary people when compact fluorescent bulbs first appeared.

"Originally, the Department of Energy was very concerned about what happened with compact fluorescent lighting when it first entered the market in that there were all kinds of variations of quality, reliability and performance," Gary Rosenfield, EVP of Marketing & National Accounts at Switch Lighting told Gizmag. (Though the lighting aspects of Energy Star now fall under the jurisdiction of the Environmental Protection Agency, when it came to specifying Energy Star criteria for LED products, it was the DoE.)

Compact fluorescent light bulbs are often criticized for being dim and slow to warm up (Photo: <a  data-cke-saved-href="" href="" target="_blank">Mathew Bajoras</a>)

Compact fluorescent light bulbs are often criticized for being dim and slow to warm up (Photo: Mathew Bajoras)


The result has been something of a minor backlash against compact fluorescent lighting, though in reality this was more down to the shortcomings of individual products and the misleading ways in which they were sometimes sold. The DoE was keen to avoid a repeat performance when LEDs arrived, since LED products also vary enormously in quality. The relevant tests, devised by the Illuminating Engineering Society, are known as IES LM-79 and IES LM-80. A manufacturer that wants to apply for Energy Star certification must first pay an approved independent laboratory to carry out the tests on its behalf. With the results in hand, the manufacturer can then apply to the EPA (provided they're up to scratch, that is).

There is no fee for applying for Energy Star certification, nor for using the label. In fact the tests in themselves do not specify pass or fail results, but instead simply quantify performance and lifespan. It's the EPA that decides the benchmarks. Light output depends on the bulb's spec, but is a minimum of 1,600 lumens for bulbs purporting equivalence to a 100-W incandescent bulb. Among the other criteria are color rendering index of at least 80, and a rated life of at least 25,000 hours – more on that in a moment.

"The LM-79 is basically the test that defines the photometrics, in other words that defines what the light performance is," Rosenfield said. LM-79 quantifies light output and distribution, as well as electrical power, allowing the calculation of the all-important efficacy in lumens/watts. It also identifies the light's color characteristics, such as its appearance, and its ability to render colors accurately.

"That's a fairly short test to run," Rosenfield explained. "It's done with spheres in independent labs. You put the product into these spheres, very expensive test equipment that basically encloses the entire fixture, and it tests all those variables." Easy peasy.

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