Published on: Monday, September 10, 2018 City Manager & Staff Blog

Sustainability and Takoma Park’s Streetlights

Frequently Asked Questions 

(Scroll down for more detail)

What stage of updating the streetlights is the City in right now?

The City is still in the planning and testing phase of the streetlight update project.

What’s next?

Additional test fixtures will be installed this fall followed by an evaluation period before next steps are decided by City Council.

Are there test LED streetlight fixtures? Are more tests planned?

At the request of City Council and staff Pepco installed test fixtures on Hickory, Oswego, and Erie. The test fixtures are Dark Sky Certified fixtures, 3,000K, and 30 – 35 watts. Pepco did not disclose which fixtures are which wattage.

Additional test fixtures have been requested that are 2,700K and wattage as low as 19 watts. The exact specification, installation date, and location of the additional test fixtures is not yet known. As soon as that information is available this page will be updated.

Is there a scientific way to determine what an appropriate brightness for streetlights is?

People have different sensitivities and requirements for streetlighting. Fortunately there are standards and guidelines for streetlighting levels that can help the City improve.  City staff has a light meter and will be measuring the light levels at all test fixtures, and additionally at select existing streetlights for reference.

Is there additional shielding available to prevent streetlight glare and to prevent street light from entering people’s homes?

Pepco is exploring options for diffusers that could reduce glare from the streetlights. Pepco has already confirmed that the vendor they are working with has add-on shielding options that can be used to address any areas where the fixture’s existing shielding is not sufficient.

What streetlights need to be updated?

  • 776 High pressure sodium (HPS) 70 watt fixtures
  • 230 HPS 100 watt fixtures
  • 78 HPS 150 watt fixtures
  • 104 HPS 250 watt fixtures
  • 14 HPS 400 watt fixtures
  • 82 Mercury Vapor 175 watt fixtures
  • 247 Incandescent fixtures

 

Details

Updating Takoma Park’s streetlights to LED, as is currently being considered by the City Council, represents a significant opportunity for improving sustainability in a time of climate change. As a City that has made public commitments to the Paris Climate Agreement, the Global Covenant of Mayors, and the Sierra Club Ready for 100% campaign, this improvement will take the City’s efforts to the next level.

A transition to LED streetlights will have the environmental impact equivalent to eliminating 912,031 miles driven by car, each year. Our existing streetlights use 850,000 kWh. Once the project is complete, streetlight energy use will drop by over 500,000 kWh. That’s roughly a 370 MTCO2 reduction, a very significant reduction in the City’s overall greenhouse gas emissions. Updating from the existing streetlights to the proposed International Dark Sky Association (IDA) certified streetlights also means less light pollution for residents and wildlife.

LED streetlights are no longer cutting edge. Rather, they are a logical next step for cities looking to improve the environmental impact of lighting choices, address public safety, and reduce costs. Dozens of major cities and counties have upgraded to LED streetlights, including Baltimore, Arlington, Detroit, Boston, West Palm Beach, Chicago, both Portlands, Minneapolis, Hillsboro, San Diego, Anchorage, San Jose, Denver, Los Angeles, Houston, Phoenix, Oakland, New York City, Honolulu, Tucson, and numerous others. If Takoma Park moves forward to having our streetlights changed to LEDs, we will be the first community served by Pepco to do so.

Staff and Council have taken many years to thoughtfully gather information and consult with a variety of experts on the streetlight update project. Issues from asset ownership, energy savings, inventory of lights, directional control and IDA certification, color temperature, overall “brightness” and visual acuity, to smart city capabilities including remote dimming and monitoring have been examined. The City participated in the Department of Energy Better Buildings Outdoor Lighting Accelerator, which provided expert technical assistance to the City free of charge. After this extensive research and discussion of the City’s options, the Council passed a Resolution in October 2016 directing staff to work with Pepco to update the city’s streetlights with smart LED technology following IDA recommendations.

At a recent progress update on the project to the Council some questions were raised about the current plan. The three main inquiries were:

  1. Will the proposed LED streetlights address light pollution and blue light concerns?
  2. How do we address the perceived brightness of LED streetlights?
  3. Should the City change its requirements and request that Pepco go out to bid again to purchase fixtures that are 2,700K vs. the 3,000K that were previously selected for the project? (“K” stands for Kelvin, which is essentially the color temperature of lights.)

Some answers to address these questions:

  1. There is a fair bit of confusion around LED technology and streetlighting, as experts on the subject readily admit. The question of light pollution and blue light is not germane to LED lights alone, but rather a general question for any type of streetlight that would be important no matter what type of lights were being installed. The proposed fixtures for the project are IDA certified, which means they limit light pollution and will REDUCE the level of light pollution in Takoma Park since the current streetlights are not IDA certified. The question of blue light is addressed by the selection of fixtures that are 3,000K. The difference between 2,700K and 3,000K is imperceptible to the human eye, not guaranteed by manufacturers, and should not impact the perception of overall brightness or blueness of the light.
  2. The brightness of any light is measured by its lumens. With LEDs, several factors can affect the perceived brightness. The goal of streetlighting has traditionally been 1 foot candle measured at ground height. IDA has recently recommended Takoma Park aim for 0.8 foot candle. We gathered light meter readings of LED test fixtures installed on several streets in Takoma Park as well as a number of existing lights around Takoma Park. These readings reveal that many of the old high pressure sodium (HPS) streetlights are in fact much brighter than the test LED fixtures, with an average for the HPS lights we surveyed of 2 foot candles. The test LED fixtures have an average reading of 0.73, lower than the recommended level. The range for the test fixtures is from 0.33 – 0.95 on the sidewalk across from the fixtures to 0.71 – 1.7 on the sidewalk directly behind the fixtures. The City can most likely achieve the desired brightness by simply reducing the wattage of the proposed fixtures. To test this, we have requested that Pepco provide more test fixtures in a reduced wattage.
  3. The difference between 2,700K and 3,000K streetlights is not perceivable at ground level. 3,000K is in fact acceptable to the IDA. Tucson, Arizona recently achieved IDA certification for its community through its LED streetlight installation using 3,000K LED streetlights.

As Sustainability Manager there are some major points I think deserve more focus as we continue this project:

  • There are three main driving factors for Takoma Park’s interest in streetlighting: improving the environmental impact of the city’s lighting choices, improving the quality of streetlight in the City, and saving the City – its taxpayers – money.
  • The current streetlights are in various states of operation and disrepair. The streetlight update is necessary and needed both for operational reasons and in the interest of consistency.
  • There are areas of the City that are not properly illuminated (both under and over lit). As a densely populated City, Takoma Park has many residents of all ages and abilities walking, riding bikes and taking public transit. Appropriate lighting levels help people see and be seen and help lower the incidence of burglaries and violent crimes. This is the balance that the proposed streetlight project is specifically designed to address.
  • The environmental impact of our lighting choices. The City’s streetlights are the single largest source of energy use for municipal operations. None of the existing streetlights are International Dark Sky certified and they emit light pollution. The new fixtures selected by Pepco address the environmental concerns by reducing energy use and the City’s carbon footprint, and having lighting that is International Dark Sky certified will reduce the current light pollution problem.
  • The cost of not moving forward is great. Not moving forward in a timely manner leaves areas of the city not being properly lit, requires the City to continue to pay high electricity bills, delays us from making a significant improvement to the environment, and can move us out of a leadership position on this issue.
  • From a financial standpoint, we have received questions about whether Pepco would want us to reduce energy since some people mistakenly believe that less energy use translates into less money for Pepco from the City. That is not the case. The City actually purchases electricity from a third party, not Pepco. Pepco provides and gets paid for the distribution – poles, wires, and fixtures – and receives the same revenue regardless of the amount of energy used. As such, Pepco has no incentive to select fixtures that are less energy efficient.

The test fixtures from Pepco installed throughout the City are 3,000K and 30-35 Watts. They can be found on Erie, Oswego, and Hickory. I would encourage everyone to look at the pilot project streets and the test fixtures. I would also encourage everyone to not judge the lights by staring directly into them (you don’t stare directly into light fixtures typically anyway I would hope!), but rather try to experience the quality and feel of the light on the ground where you are driving or walking. Keep in mind as you experience the test fixtures that this isn’t about comparison to the nostalgic orange glow of old high pressure sodium streetlights, but rather if the test fixtures provide a safe and quality environment for drivers, pedestrians, and wildlife.

There are two fact sheets from the DOE on LED technology I think are helpful to understand not just lighting technology, but also the consideration that has gone into the plans for updating Takoma Park’s streetlights.

Technical aspects of lighting color temperature and the relationship with optical safety and acuity: https://betterbuildingsinitiative.energy.gov/sites/default/files/attachments/true-colors.pdf

Department of Energy response to the AMA guidance on streetlighting: https://www.energy.gov/sites/prod/files/2016/06/f32/postings_06-21-16.pdf

Next steps in this project are continuing conversations with Pepco to address questions raised at the Council meeting and continuing to gather resident feedback. The goal is for Council to make a final decision about moving forward with this project this fall.

I look forward to continuing to work on reducing Takoma Park’s greenhouse gas emissions, and I look forward to enjoying the City’s improved streetscapes.

Gina Mathias, Sustainability Manager