This article was published in the November/December 2012 issue of LEDs Magazine.
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Another Street and Area Lighting Conference (SALC) has come and gone, and as has been the case of late the presentations were LED heavy. But the need for adaptive controls was the prevalent message at the conference although the outdoor lighting industry is desperate for guidance on energy savings that controls can deliver, the safety of controls in applications such as street lighting, and logistics problems such as utility tariff rates. The crowd left with some answers, yet questions about controls persist.
Van Duinen said that LED-based lighting can offer 50-70% energy savings, but added “it’s not enough to meet global sustainability targets.” Adaptive controls can bring the savings to 80% according to Van Duinen. Ultimately he envisions a unified network connecting street lighting and other city infrastructure. For more on the keynote, see our earlier news story.
California street-light survey
Perhaps some of the most solid information on controls at SALC came from Kelly Cunningham, the outreach director at the California Lighting Technology Center (CLTC) located at the University of California at Davis. Cunningham first shared some results from a California street light research study she conducted and concluded with some details of a case study of an adaptively-controlled, wirelessly networked lighting installation on the Davis campus.
Cunningham reported that as of 2011, 76% of the lights covered by the study used high-pressure sodium (HPS) lamps. Between 2-3% of the lights used LED or induction sources. And note that figure is high relative to the rest of the US. Recent research by the Northeast Group that we reported on in a news story said the penetration of LEDs into street lights is below 1% in the US.
The purpose of the survey, however, was more to project what happens going forward rather than to report on the status quo. Cunningham said that in conversations with municipalities cost is a common theme. She said communities need commercial payback periods of a few years, not the 10 years that have been common in many municipal products.
Cunningham briefly addressed light-source technology, declaring that LED, induction, and light-emitting plasma were all energy-efficient options. We covered some of the alternatives to LEDs in an SALC report that we ran in the fall issue of our Illumination in Focus publication. About the CLTC, Cunningham said, “We go for the right source and the right controls for the application” and said the center was technology neutral.
About safety, Cunningham said that street lighting is the “most contentious of applications for adaptive controls” because of potential safety concerns. She said that there are places where adaptive controls will never be used such as airport roadways and that there are areas where controls can be applied in roadway lighting.
Cunningham acknowledged that no one has a solid handle on how much controls can add in savings, but the CLTC is working to help deliver data on the topic. The CLTC has installed a campus-wide networked-lighting system after experimenting on a small scale with controls. Coincident with SALC, they released the first results for the project that includes 1400 lights. The focus has been on wall packs, post-top area lights, and pathway lights that were considered a “safer place to start” than street lights.
The CLTC learned a lot quickly. For example, relatively static occupancy sensing just doesn’t work. Cunningham said that an installation has to address the “occupant directional of travel.” For example, she said that having a dimmed light come to full brightness after a bicyclist has passed is not useful. So the network is a key enabler of the system being able to predict travel direction before someone reaches a luminaire that needs to come to full brightness.
Cunningham said that the same situation would apply to street lights. A networked system might need to predict that a car was making a turn onto a roadway and react with a lighting change, before the turn happens.
Outside of the controls area, there were a couple of other case studies presented at SALC that we should discuss – a new one and an update from the Los Angeles LED street-light installation that we’ve covered previously. Let’s start with the new one, because it’s also the first instance of municipalities using the DOE Municipal Solid-State Street Lighting Consortium (MSSLC) "Model Specification for LED Roadway Luminaires.” Moreover, it demonstrates how that MSSLC work helped communities in Iowa move very quickly on a project.
The Iowa presentation came from Jonathan Roberts, an energy services engineer with the Iowa Association of Municipal Utilities (IAMU), and Michael Lambert, senior lighting designer at KCL Engineering. The duo worked on a project in which 15 municipal utilities joined together to purchase LED street lights to obtain better pricing through a larger purchase.
The time line for the project was amazingly fast, driven in part because some of the municipalities were using funding from the American Recovery and Reinvestment Act that had to be spent by September 2012. Using a customized version of the MSSLC specification, the IAMU issued an RFP on December 29, 2011. Proposals were due January 18, 2012, and the supplier that won the bid was notified January 25.
The group sought bids for SSL luminaires meant to replace 250W, 150W, and 100W HPS luminaires. There were as many has five brands that distributors proposed for the project and in some cases multiple suppliers submitted bids to supply products from the same brand. The chart in Fig. 4 for the 100W-retrofit bids illustrates the relative range of the pricing relative to the low bid. Indeed pricing in that category ranged to more than double the low bid price. The winning bid was for Leotek luminaires.
The speakers showed a financial analysis for a number of municipalities that indicate a broad range of payback periods based on the inventory of lights, energy costs, maintenance costs and other factors. Algona, IA was home to the largest project. The community is expecting payback in 9.5 years based on energy and maintenance savings.
In contrast, Auburn, IA is projecting payback in just 2.4 years, although the project was a modest 24 fixtures. The big difference is energy costs. Auburn pays $0.118 per kWh while Algona pays $0.08 per kWh.
Roberts said that both the MSSLC specification and other DOE reports were essential in the success of the project. Still, the IAMU realized the need for a practical guide for Iowa communities considering an SSL retrofit. And the IAMU completed such a handbook that was to be published by the end of last quarter.
Los Angeles LEDs
Moving from a relatively small state to one of the worlds’ most populous cities, Los Angeles is also home to the largest LED street-light installation in the world. We covered the Los Angele project after Ed Ebrahimian, director of the Bureau of Street Lighting in Los Angeles, made a presentation at SALC two years ago. At that time the city had installed on the order of 20,000 LED lights. At SALC this year, Ebrahimian (Fig. 5) said the number was up to 99,000 and as of November 13 the number had climbed to 105,000.
The scale of the Los Angeles project, and the energy and carbon emission reductions, are stunning. Table 1 summarizes the savings as of November 5, 2012. Indeed at SALC, Ebrahimian said that carbon reduction was the biggest driver in the acceleration of the program. The project had been slated to take five years to retrofit 140,000 lights but the mayor accelerated the pace to finish in four years.
But it’s the lessons learned from Los Angeles that are arguably of greatest importance. The city has settled into a regular cycle of reviewing new luminaires every six months. The continuous cycle is necessary to get the latest technology. Ebrahimian’s team has increased its warranty requirement to seven years from six early on.
The city has performed a detailed comparison of failure of new luminaires using HID data it had gathered previously and data from the first 98,000 LED fixtures installed. The HID lights had an average failure rate of 10% whereas the LED lights have a failure rate of 0.2%.
The realized 63% in aggregate energy savings is far better than the projected 40% goal. And the light quality is better than expected also. The city had worried about uniformity but discovered that the LED lights far outperform HPS lights in that area.
The transition to better lighting has occurred at the same time that the city has witnessed a decrease in citywide crime statistics. Comparing 2009 with 2011, vehicle theft, burglary/robbery, and vandalism was down across the board between 7:00 PM and 7:00 AM. In aggregate, the decrease was 10.5%. Ebrahimian stopped short of proclaiming the lights as the sole difference, but they clearly seem to be a factor.
The city is also installing a wireless network on the lights. For now it is using the connectivity to automate maintenance. But in the future it could be used for adaptive control and dimming.
Los Angeles still has more street-light inventory for which it will consider an upgrade. The initial project didn’t cover the 70,000 decorative street lights in the city inventory. But the city plans to ultimately retrofit those lights as well.
Moving to a discussion of fixtures, and featuring a refreshing change of pace from typical SSL presentations at trade shows, Mark Hand, director of new products and technology at Acuity Brands presented “Managing LED luminaire costs.” And Hand’s focus was on the customer – not the luminaire manufacturer – performing the cost management.
At first the concept seemed backwards but quickly came into perspective as Hand described how the lighting community essentially over specifies luminaire requirements. The trend of specifiers setting all parameters artificially high can be especially true in street lighting, and Hand attacked elements of a specification one at a time.
Hand started with lifetime. He asked “Is 150,000 hours a realistic or reasonable lifetime?” That lifetime equates to 34 years in typical usage scenarios. Hand showed photos of a telephone, a TV, and a car that could have been from about 30 years ago, and rhetorically asked if anyone would still want to use the products today. The point Hand was making is that municipalities will likely want a different lighting technology in less than 30 years – even if the replacement is simply more efficient LEDs. Yet some municipalities are requiring luminaires with TM-21 projections that show such lifetime, and engineering such products adds cost to the fixture.
Hand took the position that for 24-hour, 7-day operation 50,000-60,000-hr lifetimes make sense. He said that for 4-hour, 5-day operation such as an office restroom with an occupancy sensor, that 10,000-20,000-hr lifetimes make sense.
By specifying a more realistic lifetime spec, buyers can allow the luminaire maker more flexibility in product design that directly results in lower prices. A shorter rated life means that you can run the LEDs hotter delivering more lumens with fewer LEDs or eliminate a heat sink.
Next Hand attacked CRI. He said, “Just because the existing lighting has it doesn’t mean it’s truly needed.” Hand acknowledged that some applications such as high-end retail need high CRI but that many such as street lighting don’t. Specifying high CRI invariably reduces efficacy meaning a luminaire needs more LEDs and has a higher total cost of ownership.
The CRI discussion led to one on binning and the trend of specifying product that fall within a 3 MacAdam ellipse in terms of chromaticity. Again some applications need tight binning, but Hand said that street lights are generally acceptable with 7 MacAdam ellipse binning.
While controls were favored prominently by most speakers at SALC, Hand took a more measured approach to that subject as well. He used a large parking lot to make an example. In a factory with a relatively small night-shift work force, he said simply having night workers park in a specific area of a lot, and turning the remainder of the lights off is a far better solution than using sensors to detect activity in all areas of the lot and controlling the lights in real time.
Hand's last topic was serviceability. He point out that a serviceable luminaire cost much more in terms of extra interconnects and other hardware. He asked, "Could replaceable be a better alternative?"
The point of Hand's talk became simplistically clear. He said that as buyers loosen the specifications that they will get more luminaire choices. And luminaire makers will have more options to buy lower-cost LEDs. Ultimately SSL becomes more affordable without compromising on what's needed in an application such as street lighting including uniform, broad-spectrum light.
The most frustrating presentations at SALC were again from utilities that see LEDs and controls as having unsolvable logistics problems. For example, John Walter, principal engineer for outdoor lighting and attachments at the National Grid utility that serves part of the US northeast addressed the issue.
Ward said that HPS has six billing points. Even lamps and ballasts from different vendors fall into the same ranges for energy consumption. He said that with LEDs everything adds variability including color temperature and driver electronics. He added, "Controls further complicates the situation." He said that National Grid looked at LED luminaires from eight different manufacturers and found they would have to account for 1202 different models in terms of energy usage to calculate bills the way the utility does with legacy lights.
Some in the audience saw the situation in more simple terms. The prevailing thought is that even with LEDs, utilities can establish some relatively small set of tariffs for which individual products are qualified. Longer term, the answer is metering in the luminaire with accurate billing data gathered over a network. But there are apparently legalities that utilities face in terms of metering capabilities designed in by lighting manufacturers.
Closing the show
SALC closed as it started with a focus on controls and networks. Michael Poplawski, senior lighting engineer at the DOE's Pacific Northwest National Laboratory, led a Wednesday panel discussion on controls and adaptive lighting. The advice was in part to learn about networks. Indeed, we've witnessed the same need and have run numerous articles about network technology that may be second nature to computer professionals but not to lighting professionals. The panel concluded that we need better standards for networks in lighting.
The MSSLC is moving to help in the area of controls. The consortium announced a draft of the "Model Specification for Adaptive Control and Remote Monitoring of LED Roadway Luminaires" document at SALC. The MSSLC has been taking comments on the draft. But be forewarned, the controls spec may be more complicated than the luminaires spec that the IAMU used for the street-light project discussed earlier.