LED Streetlight Conversion Project

Timeline​

Why is this project being done?

The Streetlight Conversion Project will install light emitting diode (LED) bulbs in DTE owned and maintained streetlights within the City of Ann Arbor, which aligns with the city's goals of increasing sustainability and decreasing our carbon footprint as outlined in the city's A2ZERO climate action plan:

• Strategy 3: Significantly Improve the Energy Efficiency in our Homes, Businesses, Schools, Places of Worship, Recreational Sites, and Government Facilities
  
• Action 3: Power Street Lighting and Traffic Signals with​ LED
  

In March 2023, the City of Ann Arbor was awarded the Carbon Reduction Grant from the Southeast Michigan Council of Governments (SEMCOG), which will allow the city to transition DTE streetlights from High Pressure Sodium (HPS) to LED lights. The city is seeking input from the public on the color temperature and wattage of the new lights.

The DTE Streetlight Selection Project will consider both the street light color temperature and the wattage, as there are tradeoffs between visibility needs, light pollution, and aesthetic preferences when brightness or temperature vary. The City is considering the following streetlight options: 29w/2700K, 29w/3000K, 58w/2700K, and 58w/3000K.

Questions and answers

​​​​NOTE: These questions and answers may be updated or revised as additional information becomes available.

What did you take into consideration when making streetlight decisions?

Staff tried to balance many different considerations, but safety and sustainability were two key areas of focus. LED streetlight conversion was identified as a key strategy in the A²Zero Carbon Neutrality Plan. City policy, specifically the Ann Arbor Moving Together Towards Vision Zero Transportation Plan, also prioritizes pedestrian safety. Staff worked to ensure that the proposed streetlights would do so, ultimately deciding that higher color temperatures and wattages are justified along major street locations with mid-block/uncontrolled crosswalks (that is, those without traffic signals or stop signs). 

City staff are aware that the color of the light (cooler vs. warmer) can change how people feel about the light, and are sensitive to the desire not to have streetlights be any brighter than necessary: both to be more sustainable (by reducing energy usage and associated costs) and to avoid light pollution. In consideration of all of the above factors, the approach to making streetlight decisions has been one of balance, trying to find the “Goldilocks" light: one that is “just right" in terms of both its brightness and its color temperature. 

Staff also had to balance operational and practical limitations given that these streetlights are owned and operated by DTE. 

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Why does Ann Arbor want to switch to LEDs instead of using the High Pressure Sodium lights I am used to?

LED lights have become the standard technology; for instance, DTE recently announced that its supplier had discontinued selling non-LED streetlights because of a lack of demand. LED streetlights are the new norm for a lot of reasons. They are more environmentally and financially sustainable (lower maintenance and operating costs). 

DTE recently announced it will be going 100% LED in the future. Why doesn't Ann Arbor just wait for old lights to burn out instead of spending money to convert now?

There are two key reasons to make the switch now. First, the City has been awarded a Carbon Reduction Program grant from SEMCOG for approximately $1 million that must be used to support this conversion; waiting too long would essentially forfeit that funding. Second, the City prefers not to install the standard LED light DTE currently offers, as the standard offering does not take into account the various considerations listed throughout this FAQ. Unless DTE agrees to switch their standard light to our preferred light (which the City has suggested), the City would need to pay some up-front money regardless.

Why does Ann Arbor want a different light from the DTE standard LED light?

Ann Arbor (in cooperation with other local governments) successfully argued that DTE's proposed streetlighting rates were too high because DTE's standard LED light fixtures are too high a wattage for the City's needs, which makes them more expensive to buy and operate. Staff have also heard feedback from a number of residents that they wanted a warmer light (color temperature of 3000K or less) than DTE's standard offerings have. For these reasons, staff's recommendation is for the City to consider other options besides the standard DTE LED offerings. 

How does the recommended streetlight differ from those DTE recommends to cities?

The LED light fixtures the City are recommending are both lower wattage (less bright) and a warmer color temperature (more orange, less blue) than any of DTE's current standard LED offerings.

Did Ann Arbor get public feedback about different lighting possibilities?*

Yes. City staff asked DTE to install four sample streetlights that aligned with ANSI/IES Recommended Practice for Lighting Roadway and Parking Facilities to minimize glare, light tres​pass, and the amount of upward-directed light and also have a correlated color temperature (CCT) no higher than 3000K. Those sample lights were two low (29W) and two medium (58W) wattage fixtures, each with a different  color temperature (2700K and 3000K).  They were installed at two locations in the city during some of the darkest times of the year, and staff asked the public to provide feedback on all these options. While no single light made everyone happy (for instance, every single light option had some people say it was too bright and others say it was too dim), the public feedback clearly favored warmer-temperature lights. The public feedback suggested that most people thought the brighter of the two alternatives shown would be appropriate to install on a residential street.

*This response has been updated to provide additional clarification on how the ANSI/IES standards were considered.

 
Why didn't you pick an even lower wattage light, to reduce costs and light pollution?

One of the goals of public engagement was to understand if there were strong preferences between the wattage options. In all circumstances, the chosen lights would be less bright than DTE's normal wattage and warmer than its standard color temperature, because staff can meet minimum brightness standards for safety while lowering costs and energy usage. Staff prioritized brighter lights for crosswalks to ensure pedestrians are visible, especially when crosswalks are uncontrolled (that is, at intersections without traffic signals or stop signs).

While there might be some locations in the City where even lower-wattage lights could be installed, there are drawbacks to having multiple types of lights, namely increased coordination, maintenance costs, and delay in responding to streetlight outages on an ongoing basis.