Not much more than a decade ago, LED fixtures and lamps were still a bit of a novelty. Significantly more expensive than traditional light sources, their performance could be spotty. Today, though, with incandescent and halogen products being pushed from the market, LEDs have become the dominant technology. Their efficiency has soared, and controllability allows for even greater energy savings and improved light quality.

However, LED energy reductions have slowed over the last few years, which begs the question—have we hit maximum efficiency? The answer, in short, is no; however, much of the low-hanging fruit in that regard has been picked. Further improvement is possible, but it’s likely to be incremental rather than monumental. However, we’re also just beginning to understand the added benefits this highly controllable light source could offer in terms of improved health and productivity.

How we got here

The first commercial white LED was produced by the Japanese firm Nichia in 1996, but commercial LED lighting didn’t begin to hit shelves until 2010 or so. The first big launch to consumers, the Hue line of app-controlled lamps, was introduced by Philips Lighting (now Signify, Bridgewater, N.J.) in 2012. Though these lamps were more efficient than incandescent products, the early commercial troffer and linear options weren’t a huge step up from the T8 fluorescent fixtures they were meant to replace. Performance issues, such as flickering and incompatibility with existing dimming systems, remained hurdles.

Fast-forward a decade, and the market has shifted significantly in favor of LEDs. Lighting efficiency standards issued by the U.S. Department of Energy (DOE) have pushed incandescent lamps out of production—LEDs are the best option for meeting new performance targets. Resulting consumer and business demand has brought costs down and encouraged manufacturer innovations. In parallel with these improvements to LEDs themselves, control system advances are driving down energy use even further.

“Some products today are getting close to 200 lumens per watt (lm/W),” said Mark Hand, vice president of engineering, indoor for Acuity Brands Inc., Atlanta, using the efficacy-rating metric lighting experts cite to measure a lighting product’s efficiency. However, these highest-achieving lamps and fixtures are generally limited in use. 

“These tend to be in applications where the luminaire is far enough away from people that the glare associated with minimally controlled LEDs is less of an issue, such as high bays or outdoor pole-mounted lighting,” he said.

More common interior fixtures now top out at approximately 150 lm/W, said Morgan Pattison, senior technical adviser to the DOE’s Lighting R&D program. Though the most efficient are typically linear luminaires, he said even higher efficacy ratings are also achievable for other LED offerings.

“From a technical perspective, there’s not a big difference in what could be achieved by other form factors,” Pattison said. “There are slightly different economics based on the product, but any product could be at 200 lm/W if people wanted to put in the effort.”

Efficiency gains plateauing

However, ongoing efficiency improvements are slowing, with industry observers seeing only small gains more recently, year over year.

“Over the last 3–5 years, LED efficacy improvements have been modest, approximately 10%–15%, and mainly driven by cost reductions in LED manufacturing,” said Chris Hutchins, Signify’s product manager for professional indoor lighting, Americas. “This has allowed more efficient use of LEDs in applications.”

Hand agrees that the great efficiency leaps made in LEDs’ earlier years have slowed recently, and manufacturers now are considering where improvements can be made throughout their operations. 

“The gains can’t be attributed to one specific technology advancement, but instead, they’re coming from a combination of minute gains across all the aspects of LED technology and production processes,” he said. “The reality is that today LED companies are moving more of their focus on cost and light-quality improvements from LEDs.”

Current-generation products have already lowered lighting loads and related energy costs significantly, so there’s also a question of whether businesses and consumers care enough about saving an additional few watts to support cost increases required for the development of more efficient lamps and fixtures. Taking an 8W lamp down to 6W, for example, would represent a 25% demand reduction, but would only result in minimal savings on monthly utility bills.

“Cost is an input in the development process of newer LED generations,” Hand said. “It is also a driver for customers, along with their application needs, like quality of light, beam and size requirements and occupant well-being. In many instances, customers will need an approximate two-year return on investment payback to retrofit their facility. If the cost for an LED with higher efficacy does not meet this requirement, it can be difficult to justify an upgrade.”

Control issues

But because LEDs are electronic devices, improving efficacy isn’t the only option for further improving efficiency—controls also play a big part in a lighting system’s overall energy use. This is especially true in commercial settings. For example, old-school fluorescent and HID lamps could suffer decreased light output and early failure with frequent on/off cycles.

“LEDs can more easily and efficiently process digital communication from control devices,” Hutchins said. “Leveraging pulse-width modulation, for example, LEDs can be dimmed down to less than 1% to maximize energy savings. Moreover, their digital nature also makes consistent color-temperature tuning feasible across a broad range of luminaires on a project.”

Hutchins noted this controllability can have a measurable impact on building owners’ bottom lines. 

“LEDs on their own are known to reduce energy consumption by more than 50% when compared to fluorescent equivalents. But the integration of controls takes it to the next level, boosting energy savings up to 75%. This is largely because the control sensors regulate light output with features like occupancy sensing and adaptive dimming to deliver deeper energy savings,” he said.

Hutchins added that those controls are evolving from hardwired, ceiling-mounted devices into fixture-mounted systems called luminaire­-level lighting controls (LLLCs), making installation easier and less expensive. 

“LLLCs are a connected system, where the majority of luminaires in a given space are regulated by built-in intelligence and controlled using cloud-based software powered by the internet of things,” Hutchins said. 

Contractors can use these capabilities to create flexible lighting zones and allow owners and managers to collect space usage and environmental data to better understand how employees and customers are actually using their buildings.

“Overall, we are entering a time of stabilization for controls, where incremental improvements in ease of use and features will be the dominant factor,” Hutchins said.

Pattison sees controls evolving to enable greater optical capabilities in terms of where light is delivered in a space and in the precision of the color it displays. 

“On the color side, for visually important occupations and human health, LED technology could produce any spectral power distribution that people decide would be helpful.”

Lighting’s possible effect on human health is a rapidly developing topic among LED developers. Research labs and private companies are exploring how different shades of white light—from warm, yellow candlelight tones up through cooler, whiter illumination that mimics natural daylight—affect our sleep patterns and productivity through the course of a day. While we may be reaching practical limits in LED lighting’s energy efficiency, these new applications could offer an attractive value proposition for possible upgrades in a broad range of settings, from nursing homes and hospitals to offices and manufacturing floors.

“The understanding of what we need from light is going to go through a pretty big upgrade, because the new technology enables the research—it’s moving forward exponentially.”
—Morgan Pattison, DOE’s Lighting R&D program

“Anywhere lighting is being used, we’re becoming more aware of its benefits,” Pattison said. “In the old days, the technology was limited, and research was performed with those limitations in mind. Now, there’s been a breakthrough. We have this new understanding and this new technology platform—and the need for a whole lot of research into how we use this platform. The understanding of what we need from light is going to go through a pretty big upgrade, because the new technology enables the research—it’s moving forward exponentially.”

Shining a light on the future

So, what can we look forward to as LED developers continue to advance this technology for lighting?

Hand sees more movement on tying lighting into larger building operations. 

“In the coming years, the integration of lighting controls into smart building management systems will provide the largest energy savings,” he said. “These systems will close the gap between how we think we can save when we initially commission the system and how we could actually save with optimized lighting controls.”

Hutchins anticipates a greater emphasis on aspects of LED products that support a larger, growing interest in sustainability. 

“This is driving the design of more energy-efficient products and systems, as well as a focus on aiding the transition to a circular economy through serviceable luminaires, reusable components and intelligent systems and services. The adoption of wireless connectivity, coupled with LLLCs, will light the way for sustainable outcomes and market improvements,” he said.

In addition to improved efficiency, Pattison sees LEDs transforming how we think of lighting and its role in our health and well-being. What started as a once-in-a-lifetime technology upgrade to replace energy-wasting incandescent and fluorescent lamps and fixtures is on the verge of becoming something much more significant.

“I think they’re going to improve and get better,” Pattison said. “As a global benefit, we can still do much better with the energy story, and, on top, there’s the productivity story. Taken together, it starts to become a once-in-a-century change. Peoples’ minds are getting opened to think beyond the old socket structure and previous functionality to get to the next level.”

stock.adobe.com / Ramzi / ern