Advancing Efficient Street Lighting through Fixture Upgrades, Adaptive Controls, and Enabling Utility Rate Mechanisms
In response to the 2001 energy crisis in California, the City of San Diego established goals to reduce energy consumption and advance energy independence. The City also launched the Energy Conservation & Management Division within the Environmental Services Department to implement programs and projects to achieve these priorities. Recognizing that street lighting is a significant source of city energy consumption and a key opportunity for savings, the City formed a Street Light Working Group (SLWG) under the Division in coordination with the Local Government Partnership to increase the City’s focus on improving energy performance in street lighting. This included the development of standards and tools to procure and deploy energy efficient lighting technologies, in partnership with regional cities and the City’s public electric utility, San Diego Gas & Electric (SDG&E).
In 2010, the City conducted the Advanced Street Lighting Technologies Assessment Project. The study provided the analytical foundation for lighting upgrades, showing that the replacement of existing Low Pressure Sodium (LPS) and High Pressure Sodium (HPS) street lights with induction and LED luminaires would increase energy efficiency, lower energy costs, reduce greenhouse gas emissions, improve color rendering, cut maintenance costs, and mitigate light pollution. With the availability of American Recovery and Reinvestment Act funds, the City of San Diego approved a city-wide upgrade of 35,000 city-owned street lights, replacing outdated LPS and HPS luminaires with efficient induction and LED technologies. These technologies enhanced light quality, increased energy savings, and cut annual electricity and maintenance costs by an estimated $18 million and $6 million, respectively.
In 2014, after considerable advancements in LED technology, the City decided to further upgrade street lighting with efficient LEDs that offered adaptive control capabilities. Specifically, the City replaced an additional 3,600 existing HPS street lights with LED LightGrid technology that delivered additional energy savings and greater return on investment. San Diego became the first city in the United States to adopt this technology, which is an intelligent lighting system that embeds wireless control GPS technology in each light pole, allowing the City to evaluate and manage energy performance in real-time. In addition, the system enabled the City to capitalize on a reduced metered billing rate structure for street light efficiencies. San Diego worked with SDG&E to map out new billing scenarios based on the utility-grade meters that allow the City to dim lights and also sub-meter for third-party applications such as parking optimization, monitoring and surveillance, traffic optimization, environmental monitoring, public safety, gunshot detection, and pedestrian planning and safety.
The City of San Diego’s Climate Action Plan
San Diego’s energy conservation efforts are supported by a comprehensive Climate Action Plan that was adopted in December 2015. The Plan outlines key strategies for achieving energy independence and greenhouse gas emission reduction goals that are supported by a broad set of City stakeholders. San Diego’s street light retrofits serve as an important component of the implementation of the Plan.
The City of San Diego Energy Conservation and Management Division
The City of San Diego’s Energy Conservation & Management Division is part of the Environmental Services Department (ESD), formed in response to the 2001 California Electricity Crisis, to pursue the city’s long-term goal of energy independence. The Division implements projects and programs to achieve their objectives, including the Street Light Working Group (SLWG; formerly the Peer-to-Peer Program), which works to deploy energy efficiency projects and share information and resources with other local public agencies. The City-wide street lighting retrofit emerged out of the SLWG’s agenda to develop successful energy conservation and energy efficiency programs.
San Diego Light Pollution Ordinance
The City requires luminaires to comply with San Diego’s ordinance to minimize light pollution and protect the Palomar and Mount Laguna observatories. Luminaire correlated color temperature (CCT) must not exceed 3000 Kelvin to maintain consistency with the City’s agreement with the observatories. This requirement reduces the energy efficiency gains achievable for LED technology, so the economic implications were factored into the street lighting assessment when comparing technologies.
The Street Light Working Group (SLWG) was formed in 2009 and funded by the California Public Utilities Commission’s Public Goods Fund, to promote energy conservation and energy efficiency. The SLWG is sponsored by the local utility, San Diego Gas and Electric (SDG&E), and the Local Government Energy Efficiency Partnership Program; the group is co-led by the City of San Diego and CleanTECH San Diego. SLWG streamlines the process for participating public agencies to adopt street lighting retrofit projects by providing specifications, financial modeling, and procurement information. In 2010, the City of San Diego launched a multi-year program to upgrade City street light systems. The first phase of the Broad Spectrum Street Light Conversion Project, conducted from August 2010 to August 2012, consisted of replacing incumbent High Pressure Sodium (HPS) systems with induction lighting and LED technologies. After conducting a street lighting assessment survey and pilot, the second phase of the Conversion Project began in 2014, replacing 3,600 existing HPS street lights with LED LightGrid technology equipped with embedded wireless GPS controls, allowing the City to track and manage real-time energy use at light poles. The second phase, beginning in January 2014 and continuing for a year and a half, included stakeholder engagement and coordination, and aligning internal resources with external providers. The City attributes its success to a robust plan for each phase of the project cycle -- planning, design, implementation, and verification.
Step One – Planning and Securing Funding: In 2009, the Environmental Services Department (ESD) issued a report to the City Council and the Natural Resources and Culture Committee to authorize funding for the implementation of a Broad Spectrum Street Light Conversion Project. Funds would be provided through a $3 million low interest rate loan from the California Energy Commission (CEC) and $2 million from the Energy Efficiency and Conservation Block Grant from the U.S. Department of Energy, as well as additional federal, state, and local funding resources (including municipal bonds). Additionally, ESD requested modifications to the Street Lighting section of the Street Design Manual to incorporate more stringent standards for City street lighting and to include authorization of induction or LED technologies as broad spectrum lighting. In 2010, the City Council approved the requested funding mechanisms for the Conversion Project. The total budget for San Diego’s full deployment of the 3,600 downtown street lights was capped at $5 million.
Step Two – Designing the Pilot and Engaging Stakeholders: The City hired a consultant to assist with a survey of residents, businesses, and other stakeholders, to provide input on the specific fixtures and features desired. The consultant also provided technical assistance with appropriate light level requirements and guidelines needed for deployment to meet City-wide standards, and to address the priorities of stakeholders – including the astronomers and local residents – and ultimately deliver energy savings for the City. As part of gathering survey data, lighting preference surveys were conducted with more than 50 residents and business stakeholders. These surveys included a questionnaire, asking participants to evaluate street lighting preferences (e.g., on performance and visibility features). These surveys helped address comfort and safety priorities of local residents and foster community ownership in the project.
The City worked closely with a local clean technology nonprofit organization, a local energy efficient lighting nonprofit organization, and SDG&E to identify the appropriate technologies to deploy and the feasibility of their integration. The City’s goal was to obtain support from SDG&E for a smart meter utility rate and to ensure that incorporating smart meters met the City residents’ needs.
Step Three – Implementing the Pilot: The City, in collaboration with the local nonprofit organizations and SDG&E, selected GE’s LED LightGrid technology, due to its wireless control system and customizable brightness features. The City then initiated a pilot in eight different testing areas to verify the LED’s adaptive controls, color temperature of the fixtures, visual appearance, and consistency with the existing downtown fixtures; the control system provided the City with a real-time energy draw per fixture and the energy draw in the dimmed state. The City tested the fixtures in a dimmed state and observed the light output on the ground and sidewalk at each fixture for verification of performance, and established an inventory baseline to measure existing energy consumption prior to the energy efficient street lighting deployment. The local energy efficient lighting nonprofit organization conducted measurement and verification (M&V) services to demonstrate post-construction energy and cost benefits. The Energy Division coordinated with City Council Districts to determine the lighting retrofit locations, and consulted City staff across several divisions for their recommendations. The City also secured a 10.5-year warranty from the manufacturer on all LED luminaires and adaptive controls.
Step Four – Verifying and Deploying the Technology: After successful implementation of the pilot, the City officially moved forward with the deployment of the LightGrid street light technology to 3,600 light fixtures. One of the drivers for selecting the LightGrid technology is its wireless adaptive controls, a unique feature that enabled the City and utility to develop a time-of-use tariff that encourages efficiency and allows the City to save on utility costs by having the necessary controls to dim street lights. Under the “pilot” tariff that was established, the City pays for electricity based on usage, versus the previously higher, flat-rate per-pole tariff. Overall, the City took six months to obtain funding, issue the request for proposal (RFP), and award the project. The design and construction of the installation of 3,600 LED lights took eight month to complete.
- GE LightGrid Wireless Controls
- This technology includes GPS location features and wireless adaptive controls allowing for accurate measurement of individual street lights.
- This enables the City to pay for actual energy consumption per pole and to monitor real-time data; this feature allows the City to capitalize on SDG&E incentives by receiving a reduced meter rate for dimming controls. The City can also customize several features, including brightness, alarms, and search tools.
- The wireless controls send the City email notifications of power issues, avoiding the need to rely on citizens to report failures.
- GE LightGrid Wireless Controls
At every stage of the project implementation cycle, the City engaged a variety of stakeholder groups, embodying a true public-private partnership. SDG&E, the local utility, was engaged from the project’s infancy. For unbiased technology studies, survey execution, and M&V, the City relied on local nonprofit clean technology and energy efficient lighting organizations, and on the 80+ local residents and business owners who volunteered their time and provided valuable input. The City involved several departments in the decision-making process by requesting their recommendations on the retrofit locations.
The City’s Energy Division and local nonprofit organizations led the evaluation of economic and social benefits, surveys, and M&V services.
As a result of lighting upgrades, adaptive controls, and enabling rate design, the City cut street light energy use by more than 50 percent from 2010 to 2015. The LightGrid wireless control technology reduced maintenance costs with longer luminaire life and reduced replacement requirements. The adaptive controls provide a lumen maintenance feature where the fixture output ramps up over time, and only produces the amount of light needed, extending the life-span and reducing energy waste.
A range of stakeholders provided positive feedback on the lighting upgrades. For example, downtown residents reported that the new lights and the ability to dim helped reduce trespassing. Life safety personnel reported an improvement in visibility with the new LED lights. With such successful results from this initiative, the City is now considering expanding retrofit efforts by testing additional smart technology applications to enhance City services with the adaptive control LED light fixtures.
Finally, the SLWG shared project processes with other cities in Southern California to assist in the replication of the successful lighting upgrade. For example, SLWG used a file-sharing mechanism to share specifications, RFPs, successful bids, and financing measures. By including the “piggy-back” or Public Agency Rights clause in all RFPs, public agencies can procure the identical equipment and services under similar pricing and terms, thus streamlining other cities’ street light retrofit projects. To date, the cities of Encintas, La Mesa, Lemon Grove, Oceanside, and Carlsbad have benefitted from San Diego’s “piggy-backing” contract model.
Tools & Resources
San Diego installed efficient LED lighting with smart technology to measure and adaptively control energy use, collaborating with the local utility to establish a tariff that rewarded efficiency measures.
Large urban: population of 1.3 million
To reduce energy consumption and utility costs through city-wide street lighting retrofits with smart technology
An inability to monitor street lighting energy use and lack of an efficiency-enabling utility rate structure inhibited energy performance improvements
Installed efficient LED lighting with smart technology to measure and adaptively control energy use, collaborating with the local utility to establish a tariff that rewards efficiency measures
The City installed 3,600 LED street lights in the downtown area incorporating adaptive controls with smart technology