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GreenStep City Best Practices Buildings and Lighting

Efficient Outdoor Lighting and Signals
no. 4

Improve the efficiency and quality of street lighting, traffic signals and outdoor public lighting.
  • LED street lights cost 3-4 times more than traditional high-pressure streetlamps, but last 3-4 times longer, allowing significant cuts in replacement and maintenance costs. They also produce 2-3 times more light per watt, cutting annual electricity savings 30-70%. Because they are electronic components they’re also far more programmable, fitting in with a retrofit program that turns lamp housings into smart grid hubs with microprocessors, cameras, sensors and wireless radios. Such a network can modify light levels to address crime/emergency responses, report on traffic, weather, air quality, sudden noises, unexpected crowds, and relay telemetry from sensors installed in the sewer or water pipes. Poles can also be rented out to mobile or cable service providers.
  • The U.S. DOE and its national laboratories predict that LED parking lot lights will reduce parking lot energy needs by more than 50% and maintenance costs by more than 80% compared to traditional parking lot lights. For parking lots whose lights are on 24 hours a day, traditional lights must be replaced every two years; LED lights need be replaced every 10 years on average. See LED street lighting presentations from the June 2014 League of MN Cities annual conference.
  • Optimizing signal timing is a low-cost approach to reducing congestion, costing from $2,500 to $3,100 per signal, and yielding:
    • Traffic delay reductions in the range of 14 - 25%.
    • Fuel consumption reductions in the range of 8 - 10%.
    • Reduction in harmful emissions (carbon monoxide, nitrogen oxides, volatile organic compounds) up to 22%
Optional for category A, B and C cities
Category C cities that choose to implement this best practice are recognized upon completion of at least one action.

Category A and B cities that choose to implement this best practice are recognized upon completion of at least two actions, including one of actions 5 through 8.
Exterior lighting for buildings, parking lots, city streets and traffic signals can contribute up to 25% of a city's operational carbon footprint. While outdoor lighting and signals are a small percentage of all lighting energy use (public and private) in the city, these uses are important opportunities for city government to address as they work to improve public sector sustainability and night time visual quality in the city. Recent advances in lighting, signal and intersection technologies allow a city to provide better quality and safer lighting for lower costs and energy usage with short capital payback periods (2 to 7 years). Additionally, as city government addresses outdoor lighting it can then use its understanding of the issues to better work with private owners in the city to improve their lighting.
greenstep advisor
Susan Zarling, Traffic Electrical Systems Engineer, MN Dept. of Transportation: 651/234-7052, susan.zarling@state.mn.us
connection to state Policy

  • The MN Dept. of Transportation has lighting performance standards that must be met for State Aid streets. Cities often use these standards for their own streets.
  • Direction for developing the state's Outdoor Lighting Fixture Model Ordinance is in the 2009 Minnesota Statutes: 16B.328. The statute directs the Dept. of Administration to develop an ordinance, which may wait for finalization of the International Dark-Sky Association (IDA) and the Illuminating Engineering Society code. The statute sets some standards for state-funded outdoor lighting that demand cutoff luminaires and consideration of energy conservation, reduced glare and minimizing light pollution. It also requires a determination from the MN Dept. of Transportation that passive methods (markers, lines etc) are not sufficient and that artificial lighting is needed. The actions listed in GreenStep are in keeping with the direction of the statute; and go beyond it in many ways.