The annual IES Street and Area Lighting Conference featured a comprehensive set of presentations on topics ranging from new recommended practices to dirt depreciation, but asMAURY WRIGHT reports, the major theme was networked street lights with services supplanting energy efficiency as the driving factor.
The Illuminating Engineering Society (IES) Street and Area Lighting Conference convened Oct. 4-7, 2015 in Savannah, GA, and as has been the case in several previous years, connected outdoor lighting was the hottest topic on the program. The driving force behind network adoption, however, has shifted from increased energy efficiency to networks as a way to enable new applications and services - for instance, in areas such as public safety. The conference also delivered on a broad set of more mundane but important topics such as the impact of dirt depreciation, operational characteristics of solid-state lighting (SSL) in harsh environments, and new ideas in LED-based area lighting design (Fig. 1). Moreover, attendees got to hear about coming advancements in LED technology and other key enablers such as driver electronics.
FIG. 1. Area lighting in a Boulder, CO, pedestrian underpass was designed by Clanton & Associates and the lighting invites pedestrians into the transit area, according to Susanne Seitinger of Philips Lighting.
Source: Photographer Sam Koerbel.
Let's start with the focus on networked lighting. Utility Georgia Power played a key role at SALC this year, given the location, and has become one of the fastest movers in the US adopting new SSL and related technology. Kevin Fitzmaurice, lighting specialist at Georgia Power, said the utility has made installation of LED-based luminaires with controls its standard course of action on new and retrofit projects.
Fitzmaurice identified seven important applications for controls, some of which are realizable now and some of which are still to come:
• Operational monitoring and control including on, off, dimming, and the ability to monitor power usage and status of fixtures
• Asset management including location and type (all operating characteristics)
• Time-of-use metering and associated control such as turning lights on during the day in a storm
• Gunshot detection and triangulation for public safety using acoustical sensors and software
• Video monitoring for security and other analytics
• Chemical and radiation detection for public safety
• Automatic luminaire registration and commissioning enabled with integrated GPS technology
Some of the ideas above have been discussed extensively before, but some are quite new. For example, GE Lighting (now to be part of the new Current, Powered by GE) had announced a memorandum of understanding (MOU) with SST Inc in the weeks leading up to SALC involving the latter' s ShotSpotter technology that can enable real-time detection and location of gunshots (Fig. 2). And Mark Wilbur, senior global applications engineer at GE Lighting, shared the stage with Fitzmaurice. The two did not suggest that ShotSpotter would be on every street light, but Fitzmaurice said Georgia Power plans to use it in select locations where crime is a known issue. The ShotSpotter platform can automatically summon police and provide a precise location of shots.
We will discuss using internal meters in street lights to determine billable energy a bit more, but Fitzmaurice did comment on it, saying that with LEDs and controls "you may save energy, but you won't save money" if you stick with dusk-to-dawn energy-use tariffs.
FIG. 2. GE Lighting will offer ShotSpotter technology for installation with networked street lights, enabling triangulation of gunshots and automatic notification of police for high crime areas.
And the final application area in the list received special emphasis from Fitzmaurice and Wilbur. Fitzmaurice compared the situation to installing a printer on a PC before and after the advent of plug-and-play technology. He said plug-and-play technology with street lights eliminates errors and lets the line crews do what they do best - install lights rather than use a tablet or smartphone to record data and perhaps take a photo of the installed luminaire. He said commissioning takes longer than installation. Georgia Power is using integrated GPS capabilities and three codes stored in the luminaire at manufacturing to allow its central management system (CMS) to know everything required about a newly installed luminaire and to commission it automatically. Note that GE has been touting the GPS feature in recent case studies.
Fitzmaurice said Georgia Power has installed 500,000 LED fixtures over the last four years. The company uses a mix of star- and mesh-topology wireless networks and DALI (digital addressable lighting interface)-compatible drivers integrated in the luminaires. The aforementioned codes are stored in the driver. Upon power-up, the network controller reads the GPS, reads the three codes, and transmits that data to the CMS.
Metering street lights for billing
Andrew Bloomfield, director of business development at Enersource Power Services, dug deeper into the concept of metering integrated into luminaires. Enersource Corp. is a municipally-owned utility that serves the community of Mississauga, ON, Canada near Toronto, and Enersource Power Services is a subsidiary that specializes in street-light design and installation for municipal and commercial customers. Moreover, Mississauga was one of the first North American municipalities to contemplate a complete conversion to SSL back in 2011.
Bloomfield, who is also vice chair of the IES roadway lighting committee, said when the 50,000-light project was planned the municipality made a bold decision to install controls. The primary mission at the time was not metering the energy used by each light, but that capability was a side thought in the planning. The metering idea met immediate resistance, however, and took time and personnel changes before all of the stakeholders agreed to evaluate the potential of metering.
The old method of billing for street lights, according to Bloomfield, is based on a calculation involving the wattage of the lamps and the ballast factor applied to a projected load curve (on/off times) that varies by month of the year. Tongue in cheek, he said, "The methodology lacks precision."
Precision and promises
The Mississauga lights can report voltage and current level, and power factor over time - everything needed for accurate billing, according to Bloomfield. But he added, "Regulatory has not been as fast moving as technology." Regulatory opposition to integrated metering has been based on a red herring, according to Bloomfield - the idea that such meters are not accurate. He countered, "Why are we using such an imprecise system to measure street lights when we could use a much more precise system?"
Ultimately, the proponents of the meters were able to win support for trialing the technology with the promise that if it didn't work the municipality would return to the old system. Moreover, Enersource installed utility- or revenue-grade meters sporadically throughout the system to check the accuracy of the luminaire meters (within a particular tolerance, noted in the following paragraph).
The revenue-grade meters are rated at ±0.5% accuracy while the luminaire meters are rated at ±2% accuracy. But Bloomfield said the results have been largely correlated. He said you can add a 5-6% premium on the metered energy to cover other energy use in the network, including the energy used by the meters themselves, and derive a square deal for all stakeholders. Furthermore, he said with 85% of the planned installation complete, the municipality is paying for a 3-MW load as opposed to a 9-MW load.
FIG. 3. Meters integrated into networked LED street lights can enable more accurate electricity billing for street-light owners, saving money even relative to situations where there is an LED-specific, fixed-rate tariff, according to Enersource.
Of course, negotiation of an LED-centric tariff could have delivered some savings as well, but now Mississauga's bills are accurate. Moreover, there are subtle savings enabled by the metering. The old and new load curves in Fig. 3 show that under the unmetered scenario the municipality was paying for full load for 90 minutes more than in the case with metering and controls.
Florida Power and Light
As you quickly learn at a conference like SALC, however, every utility or municipality has a slightly different idea about the value of networks and even LEDs. For Florida Power and Light (FPL), the motivation of their controls project is primarily automating the maintenance process and proactively preventing the impact of failed street lights. Joe Hancock, streetlight restoration leader and a lighting products engineer at FPL, said, "We've got the largest controls initiative in the world today." The Miami-area project has been expanded to eventually cover 500,000 lights. But Hancock made it clear that it was not an LED project but rather restoration with an HID embedded infrastructure.
FPL is installing LEDs in some instances, especially when a customer requests them. But the announced networking project involves installing a network controller on the existing lights that span ownership by private customers, multiple municipalities, and the utility. And Hancock said emphatically dimming is off in the future and will be driven by regulations.
Goals and expectations
The near-term goal is the automatic detection of failed lights. Hancock said, "Street lights are the last piece of equipment that we own that people have to tell us is not working." The goal is getting an automatic notification of failures before the customer calls and to automate the service process.
When FPL retrofits a pole with the network controller, the crew uses an iPad to enter all of the pertinent data about the luminaire and the pole, including the type of pole, underground or overhead wiring, type of armature, and more. Moreover, the crew photographs the installed luminaire and uses the iPad to record the GPS coordinates of the pole. Hancock said each retrofit takes 3-5 minutes, although Fitzmaurice of Georgia Power would later question that timing.
Thus far, FPL has installed 75,000 network nodes. Hancock said FPL is realizing the automatic detection and failures, and even uses voltage and power monitoring to discover some problems before the luminaire goes fully dark.
For now, FPL is using GIS (geographic information system) technology to store the data. The utility has yet to build out a CMS. FPL is planning a CMS based on the TALQ Consortium protocols. See our feature on TALQ for more information on that protocol. The FPL CMS will be required for remote on and off control and dimming.
The drive for a CMS is in part coming from a unique perspective. Hitendra Savdas, IT project manager for the FPL smart light initiative, joined Hancock on stage. Savadas said FPL has more than 700 lights that have to be turned off for turtle nesting areas. At a minimum, that operation would require 1500 crew visits annually, and if a mistake is made it impacts two poles: the one turned off inappropriately and the one that is supposed to be off but is still on. The CMS will ultimately fully automate that process.
Despite what was a mostly optimistic presentation, there was a caveat brought forward by Hancock. He said analysis shows that nothing the city is doing or is planning to do with the lighting network can generate financial savings or new revenue that can pay for the installation of a network infrastructure. Fortunately, FPL had already installed a mesh network that covers 5 million meters of roadway when it installed wireless power meters. The utility was able to piggyback the lighting onto that network; otherwise, it would not have been able to proceed.
Hancock did offer other advice to utilities facing such a project. He said proponents should remind company executives about the value of good customer relationships. In Florida, customer dissatisfaction with the street-light performance was the biggest complaint to municipalities in the area. The FPL executives supported the network project in the face of the costs, believing that it would build customer relationships.
Moving beyond SSL networks, let's get down and dirty and discuss the prevailing thoughts at SALC that LED luminaires will require periodic service, even if the LEDs and driver electronics are working perfectly. Indeed, dirt depreciation will require street and roadway lighting owners to clean the accumulated dirt and grime. Professor Ron Gibbons, director of the Center for Infrastructure Based Safety Systems at the Virginia Tech Transportation Institute (VTTI), has been conducting research focused on studying dirt depreciation over time and on luminaire cleaning methods.
Gibbons said lumen dirt depreciation (LDD) is the most significant element that contributes to light loss factor (LLF) over time. Other elements, including lumen depreciation and exposure to temperature swings, contribute far less to LLF during the rated operational life of an LED luminaire deployed outdoors.
The street-lighting technology sector developed LLF curves for high-pressure sodium (HPS) long ago. But Gibbons said those old rules no longer apply to LED-based products. Gibbon said, "We're looking at much longer maintenance cycles" with LEDs. The implication was that with HPS re-lamping cycles the lens was also cleaned. Moreover, most HPS luminaires use a similar oval dome optic whereas LED-based designs vary from luminaires with individual LEDs covered by total internal reflection (TIR) lenses to designs with a flat optic to designs more like the legacy HPS fixture.
Gibbons studied five luminaires with different optic designs in a parking lot at VTTI. In two years LDD ranged from 2% to 5%. Gibbons also evaluated the luminaires installed on the I-35 bridge in Minneapolis, MN, a US Department of Energy (DOE) Gateway project that we have reported on previously (http://bit.ly/1Oa61W4). Those fixtures have been in place for more than seven years with no cleaning. Gibbons said LDD was as great as 20% in Minneapolis.
For now, unfortunately, there is no clear-cut recommendation in place in terms of how to generally apply an LLF with LED-based products. Ultimately, Gibbons said lighting manufacturers will need to document the depreciation for their own products. And he lamented that there is no way to accelerate testing for such characterization. Street-light owners will clearly need to establish some cleaning cycle that may be longer than the HPS re-lamp cycle but far shorter than LED luminaire lifetime.
Cleaning the dirt
Turning to cleaning methods, Gibbons studied the following options:
• Wipe the optic with a dry microfiber rag
• Wipe with a microfiber rag wetted with water
• Wipe with a microfiber rag wetted with isopropyl alcohol
• Pressure-wash optic/optics from a bucket truck
• Pressure-wash optics and the heat sink on the top of luminaires
Gibbons said lighting manufacturers have widely varying recommendations for cleaning their products. Some recommend the use of alcohol while others sternly warn that alcohol can damage lenses. While the potential for damage is real were you to soak an optic or lens in alcohol, Gibbons said his team found cleaning quickly with the alcohol-wetted rag did no damage and overall proved to be the best cleaning method. Pressure washing worked equally well, but resulted in several damaged luminaires and also requires far more equipment.
Gibbons reported that it takes 1 to 2 minutes to clean each luminaire. Models with individual TIR lenses represent the high end of the range because dirt and grime gather around the edges of such optics and require more diligence to clean. Still, the 10-minute setup of the bucket truck looms as the larger time sink in the cleaning process.
While Gibbons dismissed temperature swings as a critical factor in lumen depreciation, such a conclusion may not hold true in an extreme environment. Indeed, representing the DOE's Pacific Northwest National Laboratory (PNNL), lighting research engineer Andrea Wilkerson and senior research engineer Jeff McCullough recounted the data being collected at an extreme project site along the US-Mexican border near Yuma, AZ. As we reported previously, the DOE project was specifically intended to evaluate LED luminaire performance in a setting with high winds, blowing dust and dirt, and both high temperature and wide swings. Even after six months, the light levels dropped far more than expected and the distribution pattern changed unexpectedly as well.
FIG. 4. The DOE Gateway test of LED lighting along the US-Mexican border has revealed surprising results about luminaire performance in a harsh environment with light levels dropping over time, especially away from the pole.
Wilkerson said the DOE now has data recorded after 2500, 5000, and 7000 hours of use. The rate of depreciation has slowed relative to the first six months of use but remains a concern. Moreover, the PNNL has still not nailed down the cause. Wilkerson quipped, "It's hard to imagine that all being from dirt."
The pattern shift is especially difficult to understand as depicted in Fig. 4. The light output has actually gotten brighter closely around the base of the pole while overall lumens produced have dropped. And the lumen degradation escalates as distance from the pole increases. The DOE has two-dimensional maps that detail the pattern on its website.
Possibilities for the depreciation and beam shift that the DOE is studying include issues in the driver electronics; orientation of the luminaires that may have shifted in the wind, causing the pattern change; electrical anomalies (power usage wasn't monitored early on); compromise of the optics; and even measurement error in the data gathering.
The DOE does not think the culprit is lumen depreciation in the LEDs. Wilkerson said, "LM-80 data suggest that it should have gone up." The PNNL has removed two of the luminaires to study in the lab and replaced them with two new ones. The new ones have thermocouples installed to monitor temperature in the driver, the luminaire housing, at the LEDs, and the ambient temperature.
Despite the undetermined issues with the Yuma SSL project, the DOE is generally happy with the LED performance. Lower-power LED fixtures replaced metal-halide (MH) lamps and delivered more uniform light on the border fence. Moreover, the PNNL installed the LEDs at much lower mounting heights and that would equate to lower installation and maintenance costs. And displaying Fig. 5, Wilkerson said the LEDs are creating less light pollution. You can see the three LED poles at the far left of the photo that was taken from a bluff a few miles from the installation.
Of course, light pollution and dark sky concerns were prevalent topics throughout SALC. Moreover, there have been more frequent reports in the popular press of late where citizens are unhappy with new LED street lights, complaining about lights that are too bright and about cooler color temperatures.
FIG. 5. This photo from the DOE Yuma site shows the LED fixtures at the far left of the pole line create less light pollution than the HID incumbents.
Rick Kauffman of Kauffman Consulting and a member of the IES roadway lighting committee reminded the crowd, however, that we have street lighting because it increases public safety. Kauffman presented alongside Nancy Clanton of Clanton & Associates, who is a Dark Sky advocate. Clanton has been deeply involved in the Model Lighting Ordinance to help control light pollution through regulated levels relating to zones.
The main SALC message was that the industry can provide high-quality outdoor lighting with LEDs, which can provide a safer environment than HPS lamps while also meeting the approval of Dark Sky advocates. Indeed, slightly cooler color temperatures can allow municipalities to reduce outdoor light levels because we see better under such lights. We won't cover this topic further here because we will have dedicated feature articles upcoming in that area. Also, you may want to peruse our article on CCT and sky glow from the October issue.
Designing for people
We'll close our SALC coverage with a presentation on outdoor area lighting delivered by Susanne Seitinger, global sub-segment manager at Philips Lighting. And again the focus was on lighting for humans or what she called "people-centric lighting." Seitinger asked, "How engaged are people when they are in an environment?" The talk covered area lighting where pedestrians are prominent and was based on Seitinger's study of 90 global projects in urban settings.
Seitinger challenged the outdoor lighting industry to revisit some assumptions. She asserted that streets should be lit for people rather than cars. Rather than uniformly lighting or blanketing the ground, Seitinger suggested that we curate lightscapes. And rather than assuming brighter is better, we should make better use of contrast.
Answering her question about how people engage, Seitinger said layered area lighting can encompass elements such as ambient, dynamic, responsive, and interactive. An ambient layer delivers orientation, while a dynamic layer can provide a narrative and surprise pedestrians. A responsive layer might change based on the pedestrian flow, while an interactive layer might allow citizens to control some aspect of the lighting. Not all layers will be in every area application, but Seitinger believes citizens and municipalities will benefit from more than just stark functional lighting.
One of the first examples that Seitinger presented was the Euclid Underpass in Boulder, CO, that was designed by Clanton & Associates (as shown in Fig. 1). Seitinger said that such a lighting treatment can invite pedestrians into a transit space or corridor. The layered materials on the walls create visual interest while the indirect lighting flows down the walls in a dynamic fashion. Pedestrians have plenty of light to feel safe without the luminaires being directed to the ground.
Seitinger also presented examples of installations with responsive and interactive elements. She said that the New York, NY 34th Street Ferry Terminal has a floating bubble structure that adds a responsive element based on the flow and tides of the river. And she cited the Banco de Crédito del Peru (BCP) building in Lima, Peru for its interactive elements that we covered last year.
There was, of course, far more at SALC than we can cover here, but here are some parting thoughts presented by Greg Ortt, manager of the Lighting Solutions Center of Hubbell Lighting, when he addressed future trends. He suggested control may not be needed for dimming given the efficiency march of LED sources and he is on an ASHRAE committee that might eliminate controls requirements in buildings in the future. Ortt suggested that outdoor SSL will move to warmer CCTs. In design, Ortt thinks the industry may have moved too aggressively in optics that sharply cut off the light, say, on the border of a street. Such design can create what he called a cave-like effect and even prove dangerous for pedestrians. As you can clearly discern, there is plenty more to cover at SALC next year when the event goes to Hollywood, CA from Sept. 18-21.