Lighting upgrades have long been recognized as one of the easiest, most cost-effective ways to cut a building’s energy use. Efficiency requirements are making some of these projects a necessity, as, for example, replacement T12 fluorescent lamps disappear from the market. Light-emitting diode (LED) lamps and fixtures are gaining new attention as an upgrade option, thanks to growing availability of direct replacement lamps and luminaires. However, owners choosing a simple one-for-one swap may be missing out on the savings a complete lighting makeover could offer. This new technology offers a range of possibilities for additional energy reductions beyond a simple wattage cut.
Fundamentally different illumination
LEDs are a fundamentally different light source than the fluorescent tubes and ballasts that have dominated office and retail settings for decades. Not just more efficient, these solid-state lamps and fixtures also are more directional and more easily controlled. With a lighting plan that considers these advantages, facilities might be able to get better light with fewer fixtures and cut their energy costs even further. And the burgeoning LED sensor and controls market could mean those fixtures are used less often, for even greater savings.
“The best strategy would be not to chain yourself to legacy form factors,” said Stephen Blackman, fixture designer and president of BlackJack Lighting, a startup lighting manufacturer focused on LEDs. “If you wanted to do the job right, I would not do a one-to-one replacement.”
The downside of a simple replacement effort also is clear to Kevin Willmorth, principal of the lighting design and product-development consultancy Lumenique.
“Simply stuffing a new technology into an existing lighting system rarely produces optimal results,” he said, adding that the finished product “has the potential of becoming a disaster of light pattern issues, glare-control problems and ugly end-results that produce unhappy customers.”
A reimagined lighting plan also would take new lighting standards into account. Existing installations that went into place a decade or more ago were designed for much higher lighting levels, said Gary Trott, vice president for lighting product management for LED manufacturer Cree.
“Now, in California, some designers are designing for light levels of 25–30 foot-candles,” Trott said, adding that these lesser amounts can mean a 20–25 percent reduction in the overall number of required fixtures.
And then there’s the added option of controls, which becomes both more affordable and productive when applied to LEDs instead of fluorescents.
“The big advantage you have is true dimmability,” said James Steedly, product marketing manager for MaxLite. “In the traditional fluorescent, you had an exponential level of wattage. With LEDs, it’s very linear.”
By “linear,” Steedly means that LED illumination dims in parallel with the supplied power, so an LED fixture dimmed to 50 percent only draws 50 percent of full-power wattage. A fluorescent dimmed to the same level, however, is still using 80 percent of full-power electricity. So pairing optimally arranged (and dimmable) LED fixtures with daylight and occupancy sensors could mean even greater energy savings.
These advances have come to market in an exceptionally speedy fashion. Just five years ago, LEDs trailed even compact fluorescents in both performance and cost. LED downlights first came to market in 2007, according to Trott, and the first serious LED troffer contender arrived in 2009 or 2010, according to Blackman, who added, “Before that, they weren’t even sure how to light with LEDs.” For example, manufacturers who had been attempting to match LED light sources with existing fluorescent-fixture components discovered that, instead, they needed to develop entirely new diffuser materials to take the place of the acrylic units on which they had always depended.
Since that first ceiling-fixture offering, LED products have leapfrogged past fluorescent fixtures in their efficacy ratings, which lighting professionals measure in the amount of lumens produced for every watt supplied to a fixture or lamp.
“Four or five years ago, you had 50–60 lumens per watt,” Blackman said, adding that, today, 100 lumens per watt (LPW) are easily available, and more is acheivable. In fact, Cree recently demonstrated a fixture that hit the 200 LPW mark.
LEDs also now are surpassing fluorescent products in the quality of the illumination they produce, especially as measured by their color rendering index (CRI), which expresses a lamp or fixture’s ability to accurately render an object’s color; a CRI of 100 represents the highest level of accuracy. Fluorescent tubes generally feature CRI ratings of 70–80, while the latest LED products often hit a CRI of 90 or better, according to Trott.
“LEDs used to cost $3 for a high-power chip,” Steedly said, referring to the solid-state lighting (SSL) sources that are the basis of any LED lamp or fixture. “Now you can get a 3-watt, high-power chip for $0.55.”
If you’re not already doing so, now could be the time for you to begin advising their lighting customers about the benefits of a project that incorporates LEDs. The upfront cost could be more than that for a simple replacement effort, but your clients could trust that reduced maintenance would be an added benefit with a new SSL system. While a standard fluorescent tube might have a rule-of-thumb lifespan of 12,000 hours, according to Blackman, LEDs might function 40,000 hours or more.
Why lighting professionals matter
Making the most of such an effort, though, could require a lighting specialist’s assistance, and you should also learn as much as you can. Willmorth recommends professional design help even with a simple one-for-one swap.
“You must understand the optical characteristics and light distribution of the fixtures being considered,” he said. “For example, installing retrofit lamps will likely narrow the fixtures’ light distribution, creating uneven lighting in a space. On the other side, replacing louvered troffers with ‘volumetric’ lighting products that spread light at higher angles will reduce light levels directly below the fixtures and potentially increase undesirable glare.”
In addition to spacing, a lighting consultant also could be helpful when it comes to deciding on the appropriate color temperature for a project. LEDs are highly “tunable” when it comes to the color temperature quality of their light output. Where incandescent and fluorescent lamps often are grouped into simple “warm” (or “soft”) and “cool” categories, LEDs more likely will be labeled with their specific color temperature in degrees Kelvin. Somewhat counterintuitively, light quality becomes increasingly cool at higher temperature ratings.
“The scientists know how to control the color, but what they don’t know is what people want or should want,” Blackman said. “They’re giving more choices than the average building owner or contractor knows what to do with.”
A lighting designer also might better understand the specific testing data reputable manufacturers now supply for their lamps and fixtures, Steedly said. These include LM-79 testing, which verifies efficacy and color characteristics (including color temperature and CRI) and LM-80 testing, which covers lumen maintenance (essentially, lifespan) of LED light sources.
The time is now
The rapid evolution of LED products could prompt a wait-and-see approach for owners and facility managers interested in seeing what greater improvements might be coming in the next few years. However, Blackman, Steedly, Trott and Willmorth agree that such a strategy would overlook the very real savings available in today’s vibrant SSL marketplace.
“If the ROI for a retrofit pays off within 18 months to three years, at any time, there is no reason to wait,” Willmorth said. “Delaying a retrofit … only increases costs of operation now. If you count these delay costs against the existing system, you are simply wasting money.”
Trott offered a real-life example of Willmorth’s reasoning, citing a Cree customer who was among the earliest adopters of the first viable LED downlights.
“They have literally saved tens of thousands of dollars since 2007,” he said, offering this facility’s experience as a lesson for those who would postpone their own upgrade to await future improvements. “Any incremental improvements will be more than washed away by the energy savings they didn’t realize.”