Smart Urban Lighting Trends

With a new year at hand, it is a good time to look back at what occurred in 2015 and try to forecast what lies ahead for 2016. It has been a watershed year for LED outdoor lighting. LED now comprises more than 50% of all new public outdoor lighting fixtures sold and this percentage continues to grow rapidly. As predicted, the cost effectiveness of LED has effectively virtually older technology HPS from new public lighting installations. With average LED roadway fixtures dropping from $155 in 2014 to $125 in 2015, HPS can no longer be considered an economically viable alternative for most new and retrofit installations. This change is due to the parity of fixture costs with HPS, as well as the increased cost of re-lamping and higher operating costs associated with them. While some cities will continue to re-lamp and do spot replacement of damaged HPS fixtures, it will be extremely difficult to justify group replacement of any public lighting with anything but LED.

Typical luminaire efficacies for LED roadway fixtures now average 120 lumens per watt (LPW) with some reaching 145 LPW. In 2014, most LED fixtures were in the 80-90 LPW range. If this pace continues, we can expect average performance in the 150 LPW range by the end of 2016. LED luminaire efficacy now exceeds HPS by approximately 50% and may be double by the end of 2016.

However, another efficacy trend is emerging that isn’t getting enough attention. The newest LED chips are quickly closing the efficacy gap between warm and cool-white lighting. Just two years ago, the typical 3000K to 5000K CCT delta was about 25%; today it is closer to 10%. This will reduce the economic pressure to use cooler color temperature fixtures that are proving less popular with the public, produce more glare and skyglow, and are responsible for more ecological problems. In response to these concerns, the City of Davis, California, took the unprecedented step of halting an LED retrofit in progress; 4000K CCT fixtures that were already installed were swapped for 2700K CCT ones. Davis also reduced the illumination levels at the same time due to public complaints, reducing the energy consumption by 25% over the original LED fixture choice.

The Davis LED retrofit has “illuminated” another important issue that has been consistently overlooked by most cities and has resulted in significant blowback by the public. Davis, like most cities, has designed their LED replacements to duplicate the measured luminance of HPS on the road surface. In almost all cases, the public has responded with complaints that the new streetlights are too bright and glaring. Confused engineers look at their light meters and tell their supervisors that they are using the same lighting levels as before. A fundamental difference has been revealed in the visual performance of broad-spectrum white light from LED vs. the very warm yellow glow of HPS. While research has already identified this visibility improvement, lighting standards have not evolved fast enough to include it in recommended practices. The result of not updating lighting standards to acknowledge the improved visibility of white light is costing cities millions of dollars in potential energy savings and making communities look and feel more like shopping center parking lots. It is contributing to a serious degradation of the ambiance of many neighborhoods and, unfortunately, seems to be beyond the understanding of many city lighting engineers and some designers. It’s not just a numbers game: the color of light matters and should be considered more carefully in urban planning, especially in historic neighborhoods.

However, even if lighting standards were revised tomorrow, it is unlikely that most cities would reduce lighting levels. Current standards already allow for approximately 50% reduction in lighting levels for most streets after rush hour, but transportation engineers routinely fail to recommend adaptive controls that would allow cities to dim lighting to meet current standards. The most cited reason is a fear of litigation; the second is a concern that the public will perceive lower lighting levels as less safe. Herein lies a fundamental disconnect between public perception and reality, and a serious missed opportunity during municipal retrofits. As LED light is perceived as “brighter” than existing HPS, LED lighting levels that are 30-50% lower than HPS will been perceived as equivalent by most. So while the public would not notice the reduction and visibility would be improved – and 30-50% more energy, money and CO2 savings could be obtained – nebulous legal concerns will continue to slow progress. Now is the time for the Federal government to address this very real obstacle to help meet global climate initiatives.

A recent LED retrofit in Portland, Oregon, was documented with a Department of Energy Gateway report; it should be on the required reading list for all cities planning a lighting retrofit. It details one of the recurring issues that stymie too many cities: revising utility tariffs in order to actually benefit from the reduced energy consumption of LED fixtures. We documented this concern in our review of the Cambridge, Massachusetts retrofit that was further complicated by their use of off-peak dimming. In both cases, the cities have had to buy back the streetlights in order to realize significant cost savings.

Across the country, utilities are not making it easy to transition to LED, either by revising tariffs or by accepting the energy usage data available with the centralized management systems (CMS) of smart controls. The Portland Gateway report shows in agonizing detail how long and painful negotiations can be, even after the decision is made to buy the streetlights and poles back. In an effort to maximize their return on investment (ROI), it appears that many utility companies are driving cities to sever long-standing maintenance contracts due to their unwillingness to share equitably the cost savings that result from LED retrofits. Claims of increased initial capital investment, unknown future maintenance costs, and reliability are evaporating but they still cling to antiquated, rigid models for developing streetlight tariffs that are discouraging many cities from switching to LED. This institutional resistance is costing millions of dollars and tons of wasted CO2 that cities and the nation can ill afford. Utilities will also lose traditional value-added revenue in the future as cities begin the process of handling maintenance in-house or by independent contractors.

There also seems to be another trend surfacing to skip the installation of smart controls for dimming and instead choose a fixed dusk to dawn lighting level, somewhere between the recommended illumination levels at peak and off-peak traffic times. This was the case in Portland and Davis; by doing so they were able to achieve approximately 75% in energy reductions, while being responsive to the public’s feedback that recommended light levels are too high. This is a progressive approach to maximizing energy efficiency while deferring the decision to adopt smart controls to a later date. It’s also the result of a reticence among many city DOT staff to add the complexity of controls at the same time as making a major shift in lighting technology.

Though understandable, deferring installation of smart controls will significantly increase the installation costs later and can potentially make the justification to install them afterward more difficult. The result being that cities opting out of controls now, may not reap the additional benefits of using them for decades.

While smart controls have certainly arrived, to date only a handful of cities have installed them and less than 5% of LED streetlights have them installed. As most cities are not ready to dim lights to save additional energy, the additional investment in controls are perceived as an option that isn’t needed now, complicates commissioning, and will only increase the payback period.

However Los Angeles recently made the decision to add controls five years after their LED conversion, primarily for the ability to monitor operation and improve response by maintenance crews. They also have contracted to be one of the first cities in the world to install 4G LTE wireless micro towers using Philips SmartPole. Another promising benefit to installing smart controls is being demonstrated in San Diego by General Electric. Their Intelligent Cities system includes sensors that track empty parking spaces and can communicate this to motorists to reduce time, money and CO2 spent circling the block. It may be that hi-tech features like these will drive widespread adoption of smart controls in the future.

These trends show that a convergence of factors will accelerate the transformation to LED streetlighting in the near future. As innovative financing options like Energy Service Companies (ESCO) remove the capital cost obstacle and reduced fixture costs and operating expenses shorten the payback period, we should see more cities take the plunge. Hopefully we will learn from the cities that have taken the time to do the transition right. The best lesson to learn from the past is to not repeat the mistakes in the future. No LED public lighting should be considered without a pilot installation that involves public feedback. The days where DOT staff makes lighting decisions without consulting the community should be over. A successful transition to LED needs the input of the community that will have to live with it. Color temperature, lighting levels and dimming options should be demonstrated and an experienced lighting design firm should be contracted to help manage the process. The results will endure for decades. Let’s get it right the first time.

Reducing global lumens