Field evaluations of LED lighting show benefits beyond reduced energy usage (MAGAZINE)

June 11, 2013
Industry-specific field demonstrations will play an essential role in assessing the benefits of solid-state lighting, especially when looking at factors that go beyond energy savings, say Martha Carney and Howard Wolfman.

This article was published in the June 2013 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete June 2013 issue, or view the E-zine version in your browser.


LED research projects clearly demonstrate that solid-state lighting (SSL) has come a long way in just a few short years. Evaluations have been conducted by our organization in collaboration with multi-stakeholder groups including electric utilities, municipalities, on-farm researchers, and LED manufacturers. Working both to help specifiers choose optimum energy-efficient lighting systems and to accelerate SSL adoption is not easy, however, and consumers, municipalities, and utilities can have very different purchase motivations.

Working with a diverse group of LED manufacturers often provides an early peek at exciting new product features or the opportunity to test prototypes before they enter the commercial marketplace.

However, the excitement of SSL can often be tempered by utility clients, who are naturally averse to risk. The business model of a utility is built on ensuring reliability while generating predictable earnings for shareholders with little, if any, room for mistakes.

However, a few failures — going back to the drawing board — is typical in LED product refinement and is a natural part of getting things right. The real question is: "Can rapid innovation co-exist within a utility environment?" At times, the answer seems like combining oil and water – they just don't mix.

The good news is that more utility-funded LED field demonstrations and other market-based field evaluations are enabling us to characterize the industry and design new programs around energy efficiency. Also, smart lighting is well-positioned to align with the smart grid concept. Such initiatives create more motivation for utilities to go forward, albeit with cautious optimism.

The pace of change

Get ready: lighting innovation is going to cause huge changes. However, the pace of change will depend on critical decisions made by businesses, policy makers, leaders, and investors over the next 3–5 years.

Also, field results are providing insights into the energy-related and non-energy-related benefits of LEDs that go well beyond kilowatt-hour savings. But are these enough to motivate municipalities, and utility customers? Our research reveals that barriers to SSL adoption beyond cost still exist. These must be addressed to truly accelerate wide-scale market adoption by consumers and the utilities, whose grids must respond accordingly.

Table 1

It's generally understood that we are experiencing a major market-transformation event in lighting, which means that more services are required. Lighting companies that sell just light bulbs will either disappear or reinvent themselves to provide the market with services to support the advancement of SSL and adaptive controls. Examples of services are illustrated in Table 1 for market-ready LED niche applications.

Validated energy savings

Real examples where energy savings can be validated are compelling. Table 2 shows results from a 120,000-ft2 industrial cold-storage warehouse in Indiana, which was converted to LED lighting. The data illustrate significant energy savings for both demand (kW/kVA) and usage (kWh/kVAh) and a validated 68% energy saving from the 58, 160W LED high-bay fixtures evaluated in the study.

These savings were realized during peak times. Because of a new ability to leverage two-minute occupancy sensing, on average only 32% of the fixtures were recorded as on at any one time during a normal business day. These results are sure to get the attention of facilities managers, with SSL providing real opportunities to reduce operating costs for both energy usage and demand. However, this is not yet a home run, as photometric performance after one year suggests evidence of a notable percentage drop in foot candles. Hence, the jury is still out about reliability and whether this LED light source will survive to LM70 after 50,000 hours.

Table 2

LED performance in classrooms

School-based LED demonstrations show a recent and compelling story, with some (but not all) LEDs being ready to compete against linear fluorescents when comparing foot candles at desk level.

Table 3 illustrates that 2012 DesignLights (DLC)-rated LEDs could easily meet and surpass Illuminating Engineering Society of North America (IESNA) classroom standards. However, light performance varied widely by manufacturer, suggesting the importance of upfront evaluation at the test area before making a scalable procurement decision.

Table 3

The good news is that a 20-year total lifecycle cost analysis for these applications shows that LEDs can be the least-cost lighting solution in 2013. This is especially true in regions with higher kilowatt hours and if another layer of energy savings is realized from lighting controls. The problem is that schools typically look at payback first, making 8–10 years seem too long for an investment in LEDs when compared with low-cost, high-performing fluorescents and ballasts.

However, some utilities are providing incentives to encourage the use of LEDs and advanced lighting controls in after-the-meter applications, especially for equipment that can reduce peak load. Common rebates include refrigerator-case lighting, recessed cans, parking-garage lighting, and canopy fixtures. To mitigate risks from disappointed consumers, a utility's first line of defense for an incentive is to require DesignLight certification.

However, LED kits for linear-fluorescent replacement create new challenges driven by a concern for safety, especially when they are retrofitted into existing fixtures. Some utilities are putting the onus on the LED manufacturers to require proof of compatibility prior to LED lamps being installed. Alternatively, they may require product labels instructing there is no turning back when fluorescent ballasts are disconnected and fixtures are retrofitted to LED.

Use of controls

Using controls has been shown to increase energy savings by between 20 and 50%, depending on application. However, evaluations performed by PNNL (Pacific Northwest National Laboratories) have shown that not all LED systems are compatible with all control protocols. Real-world evaluations need to be conducted to verify compatibility of specific LED systems with specific controls.

Agricultural applications

SSL is creating new opportunities for niche agricultural lighting. For example, large manufacturers such as Philips and Osram Sylvania are offering spectrally-tuned LED lamps for horticulture applications. Also, smaller firms including Once Innovations, Luma Vue, and NextGen Illumination manufacture LED lamps exclusively for the poultry industry.

A growing collection of marketing claims suggest plants, livestock, and poultry have different spectral sensitivities, where exposure to the correct wavelength may instigate accelerated seed to retail time, increased production, or some type of growth response. The bad news is that these growth claims are not substantiated by enough scientific, repeatable research and are lacking in pragmatic real-world business analysis.

The energy-efficiency gains from SSL on farms are real and measurable. In collaboration with university-based researchers, many on-farm technology demonstrations have evaluated conversion to LEDs. These validated matched or better lighting, an energy savings of 40–50%, and good power-quality characteristics compared to HID and fluorescent lighting.

Table 4

Perhaps coincidentally, on-farm research efforts also implied growth and/or production gains, including increased milk yields and a percentage increase in poultry body weights after 42 weeks. Birds were noticeably calmer under LEDs compared to the control group (Table 4). Researchers concluded that growth or production responses caused by wavelength or LED light intensity might be anecdotal, but this certainly warrants further study and a validation of repeatable results.

These growth and production impacts begin to get at the heart of exciting new attributes that the market will embrace, which revolve around buying lighting to make money. Think of the economic development gains to be realized by farmers who use this new light source in controlled-environment agriculture.

However, an agricultural environment is typically dirty, hot, and humid. Thus, the research question at hand is whether the thermal design of LEDs can maintain light performance without rapid lumen depreciation. Our findings tend to suggest not, and smart LED purchasers today may consider including lumen degradation in product warranties to mitigate that risk.

The Cooperative Research Network of the National Rural Electric Cooperative Association (NRECA), along with the New York State Energy Research and Development Authority (NYSERDA), are supporting new research initiatives in 2013 to better understand LED impact on animal growth and crop production as this new value could provide substantial benefits to US agricultural production.

SSL streetlights

Municipal and utility stakeholders have different or competing motivations for SSL and adaptive controls for streetlights. That was evident after interviewing more than 12 investor-owned utilities and municipal stakeholders throughout North America to publish a report for CEATI International entitled "Best practices guide to SSL and adaptive control technologies for street lighting utility rates."

For example, utility-owned and maintained streetlights typically run during off-peak. This means there is less motivation for LEDs to contribute to efficiency goals compared with other LED applications that can help reduce peak demand. Results also suggest that municipalities are driven to SSL by energy and maintenance cost savings, while utilities are far more concerned about validating reliability and other important electrical and power quality characteristics first and are perceived as dragging their feet.

The research also disclosed that utilities perceive dimmed streetlights as a risky proposition. The majority were not yet prepared to consider adaptive lighting technologies on streets out of concern for liability.

Regional energy-efficiency groups

Other good news is that more energy-efficiency policy groups in the country seem to be gearing up to understand impacts from SSL and the new role for utilities. Lighting program design, where CFLs were once the mainstay, has been turned upside down. Newer approaches to field evaluation, measurement and verification must include a lumen-based analysis as well as characterizing the incremental efficiency impacts from the use of lighting controls.

Surprisingly, utilities are beginning to understand this disconnect between SSL and energy-efficiency programs. Total resource cost (TRC) does not do the job of assessing the costs and benefits associated with an investment in LEDs. Utility regulators need to quickly start to see SSL as a benefit to society and to determine how that will be handled with ratepayers in future electricity costs.

Discussions about LED technology seem to include a fear of repeating the same expensive and disappointing consumer acceptance of fluorescent technology. Much of that is driven by less-than-stellar acceptance of CFL light color, quality, and wasted use of public dollars.

A customer-centric focus is the foundation for entrepreneurial success. Results from our subjective assessments report good news, as acceptance of LEDs is quite high within the commercial sector. In fact, interviewing hundreds of survey participants about LED fixtures installed on streets, in parking lots, at industrial facilities, within classrooms, or on a rural farm, customers tend to "most prefer" LEDs by a factor of more than seven compared with conventional HID and fluorescent lighting.

Calls to action

Field work opens our eyes to the good, bad and sometimes ugly side of innovation. Here are recommendations that might help:

Action 1: A call for industry-specific field research to understand and identify the non-energy impacts from an LED light source. The existing evidence is intriguing, but scarce and is not used fairly when unscrupulous LED vendors make growth or production claims without controlled study and repeatable findings.

Action 2: For general illumination, a national effort is required to benchmark the efficiency gains from SSL and the incremental energy savings realized from lighting controls, with a sufficient margin of error so utility LED programs can be aligned with SSL. There is debate as to where this initiative should reside, but general consensus suggests either NEMA, IESNA, or CEE, or even regional energy-efficiency organizations.

Action 3: Help consumers better understand lifecycle costs. It's not realistic or fair to measure the investment in SSL using simple payback when the fundamental long-term benefits are not captured. Old habits are hard to break, but we must be consistent on lifecycle costs and making the concept of net present valueas easy to understand as payback.

Action 4: If we keep lowest cost as the driving force for LEDs, we will likely go down the same unsuccessful path as CFLs. It is important that consumers embrace LED lighting because of efficiency gains and its new value so that cost will become inconsequential.

Action 5: Continued, regular training and education on all fronts, including utility regulators. Our work continues to suggest that the marketplace compares SSL to light bulbs and does not fully understand they are fundamentally different. Installers are not educated on the correct installation of adaptive controls or how SSL, wireless, and remote wireless products will integrate with building management systems.

Action 6: Sub-par products must go. Good-performing LEDs will be a major force to be contended with on both sides of the private and public-sector equation, but field demonstration is a requirement because of wide performance variations.