US Government to Crank Lightbulb Efficiency Up to 120 Lumens Per Watt

The U.S. Department of Energy is cranking up the minimum lightbulb efficiency level to 120 lumens per watt, up from the previous standard of 45 lumens per watt. The new standard, announced in December 2022, will collectively save consumers $20 billion and reduce carbon emissions by 131 million metric tons over 30 years, according to the White House.

This story started with former President George W. Bush, who brought in energy standards in 2007 before LED bulbs existed. Buried in the legislation was a time bomb—the requirement that by 2020 all bulbs must deliver 45 lumens per watt. The Trump administration and the big bulb manufacturers tried to defuse the bomb and keep making halogen and other popular and profitable bulbs, but then President Joe Biden got elected, and 45 lumens became the law once again. And now they are cranking it even higher.

This is a remarkable story when you look at the history of lighting. Once, only the rich could afford artificial light. According to a 1994 study, tallow candles once cost 40.3 cents per 1,000 lumen hours. An Edison filament lamp cost 0.6 cents and a compact fluorescent light (CFL) bulb cost 0.12 cents. The new bulbs will probably cost half that again. Light is now almost free.

Not long ago, we all used incandescent bulbs that pushed out 10 lumens of light per watt of power—a lumen is about the light of a birthday candle a foot away. Those horrible compact fluorescent Gorebulbs put out 63 lumens. My Hue RGB LEDs give me about 78 lumens, depending on the color; cool blue lights are the most efficient, which is why we have such ugly streetlights. Making 120 lumens per watt the minimum is an astonishing leap.

Experts agree. “The LEDs on today’s store shelves are a great product, but it turns out the best technology can make the bulbs even more efficient," said Andrew deLaski, the executive director of the Appliance Standards Awareness Project. "We use so many light bulbs that this improvement would meaningfully reduce energy costs for households and businesses while cutting climate pollution from power plants."

Some suggest it will be difficult to get warmer tones and a high color rendering index (CRI), a measure of the quality of the light. A comment submitted to the government noted, "Higher color rendering index (CRI), in particular, red-rendering, requires expenditure of more energy than what your rule would allow, with technology known today. Your rule effectively becomes a rule mandating depressing, unnatural, blueish light—exactly what the CFLs were known for when they first appeared on the market about 25 years ago."

The commenter makes a good point. The legislation specifically exempts "circadian-friendly" bulbs designed to change color over the course of a day because they only pump out 87 lumens per watt. Will other color-changing bulbs like my Philips Hue make it through?

However, Philips is now selling ultra-efficient bulbs that pump out 210 lumens per watt—that meet what they call their eye comfort criteria—and are not at all like old CFLs. And they have not filed any complaints about the rule yet.

Others complain they hate the flicker of LEDs and will never give up their incandescents. "Stock up before August!" said the Wyoming-based nonprofit newspaper Cowboy State Daily.

But Philips noted that flicker is often a function of bulb quality.

"Lighting products which exhibit flicker or the stroboscopic effect are considered as lower quality lighting. TLAs [Temporal Light Artifacts] are not only annoying for people but also have impact on the comfort of the eye, general comfort and visual performance."

They are often a result of variations in the input signal and can be dealt with. Philips added: "Methods to suppress fluctuations in the light output of LEDs and, at the same time, lower the visibility of unwanted TLAs are known. These methods, however, require compromise on cost and efficiency and require more physical space while lowering the lifetime of LED products with any architecture."

Another complaint about LEDs is the quality of the light, which is measured by the CRI. Most LEDs work like fluorescent bulbs, with an ultra-violet LED exciting the white phosphor coating inside the bulb. You want a smooth spectrum as you get from incandescent bulbs, but cheap LEDs have spiky spectra. But Philips said beware: CRI is subjective.

"The preference of users is not always coupled directly to the CRI value. A higher CRI source is not always more preferred. Color saturation (vividness), especially red saturation, also plays an important role in preference. Some over-saturation is in general preferred by people, because objects look more colorful. The preference for skin tone appearance is different, also between cultures."

We grew up with warm incandescent bulbs, and that's what we like best, even though they are a bit red.

Everything is a compromise. Higher quality light generally means a more expensive and less efficient bulb. It will be interesting to see if the manufacturers can achieve 120 lumens per watt and still deliver the quality of light that we have come to expect. And my color-changing, internet-connected Hue bulbs had better work!