As LEDs mature, light quality is improving
April 15, 2015
Two decades ago, the invention of the blue LED launched a fundamental shift in the world of lighting. It was the beginning of the end of the energy-intensive incandescent bulb, offering the potential to slash global carbon dioxide emissions by hundreds of millions of tons.
But despite the technology’s environmental benefits — which won its creators a Nobel Prize last year — the original LEDs also came with aesthetic challenges. (“It feels like I’m in a strip mall in outer space,” one resident of an LED-lit neighborhood recently told the New York Times.) Now that’s finally changing, as manufacturers begin to create LED lights that can better meet specifications.
One of the biggest issues has been color variation between different fixtures, different manufacturers, and even within the same light over time. “It’s not a new problem, but it’s a problem that’s becoming more obvious and problematic with the widespread emergence of LEDs,” says Star Davis, a lighting and daylight designer in Arup’s New York City office. “All of the sudden, nothing is white — it’s shades of pink and green and different types of yellows.”
By taking a new approach to manufacturing LED products, a San Jose–based company called Xicato is now able to precisely tune colors so they fall within a tight specification and remain stable throughout their lifespans. “It should still match the designer’s intent five and ten years down the road,” says John Yriberri, the firm’s vice president of business development. While most LED lights are made with a single deposit of a material called phosphor, Xicato uses multiple different layers of phosphor to control the color.
Xicato has also solved other LED challenges. “We’re doing a lot differently than the industry now,” says Yriberri. “When we started, the quality-of-light story for us was consistency. But then we realized that it was also about color rendition appropriate for the space, and the delivered light, and an adjustment of light level. That required us to innovate in each area.”
One of the company’s new technologies allows for better control of the angle and illumination of the light in a space; another allows for dimming and smooth transitions while preventing flicker. The lights also use unique technology to render colors naturally and can even be used to enhance certain colors. For example, “in a retail environment selling jeans, you may want blues enhanced,” explains Yriberri.
The color-enhancing feature goes beyond the capabilities of a traditional bulb. “We were up to incandescent quality some years ago,” says Yriberri. “Now we’re at the point of expanding way beyond what incandescent and halogen can do, because we have the ability to tailor our spectrums to meet certain applications.”
A handful of other startups are also testing innovative ways to manufacture LED lights. Silicon Valley–based Soraa uses pure gallium substrates to make lights, while the rest of the industry grows gallium crystals on a different type of substrate, like sapphire or silicon. The change means that Soraa’s LEDs emit more light, offer more precision, and cost less to produce.
Despite these advances, much work remains to improve the quality of LEDs as a whole. One challenge is outdated metrics for color rendering. “Right now, you’re comparing if the colors are rendered similar to something that’s lit by an incandescent or radiant body,” says Davis. “It’s a scale of 1 to 100. But it’s really not enough to have just one number.”
The answer may be something called the Gamut Area Index, which tests fixtures and plots colors that can be rendered on a graph so that a particular light can easily be compared to another. “It’s scientific testing to prove what your eye is seeing and not seeing, as opposed to one number, which can’t tell you any of that information,” Davis explains.
Davis believes that if architects and designers push for the adoption of the Gamut Area Index and ask manufacturers to begin producing more options, the base level of quality will improve.
“The pace of innovation of LEDs within the last five years has been extraordinary,” she says. “With the right financial motivation — with enough educated designers and consumers — the industry will be pushed to produce a quality product.”