Investigating the Conversion to LED Streetlighting on Nantucket

Sponsors:	Nantucket Energy Office (NEO), Nantucket Lights
Sponsor Liaisons:	Lauren Sinatra, NEO Gail Walker, Nantucket Lights
Student Team:	Brendan King, Luke Marcoux, Frederick “Forrest” Miller, Samuel Sands
Abstract:	Light pollution adversely affects the environment, public safety and health, and energy consumption. Light pollution is the result of scattered artificial light, predominantly from sources such as streetlights as well as interior and exterior building lighting. To address the problem of light pollution and reduce costs, many municipalities throughout the United States have been implementing new policies, such as LED streetlighting. LEDs come with many benefits, such as reduced energy and maintenance costs, as well as the potential to reduce light pollution. In this paper, we discuss the best practices for a LED streetlight conversion for the Town of Nantucket, Massachusetts, as well as the benefits that this project will bring the community.
Link:	Final Report: NEO Final Report Final Presentation: NEO Final Presentation

Executive Summary

Light pollution adversely affects the environment, public safety and health, and energy
consumption. Light pollution is the result of scattered artificial light, predominantly from sources
such as streetlights as well as interior and exterior building lighting. As of 2016, 80% of
Americans cannot see the Milky Way from where they live, even on clear nights (Falchi et al.,
2016). To address the problem of light pollution and reduce costs, many municipalities
throughout the United States have been implementing new policies, such as replacing existing
streetlights (typically high-pressure sodium or HPS lights) with light emitting diodes (LEDs).
LEDs come with many benefits, such as reduced energy and maintenance costs, as well as the
potential to lower light pollution levels.

As an island 30 miles from the coast of Cape Cod, Nantucket is one of the darkest places
on the east coast and organizations such as Nantucket Lights, a citizen advocacy group, are
dedicated to limiting light pollution to address a variety of concerns, including preserving
Nantucket’s dark sky. Currently, Nantucket depends on two undersea cables for its electricity
and the Nantucket Energy Office (NEO) and town government are committed to promoting
energy efficiency and conservation to minimize costs that would be incurred by the installation
of a third cable. In a confluence of interests, NEO and Nantucket Lights are exploring the
potential of converting the existing high pressure sodium (HPS) cobra streetlights to
LED to reduce electricity consumption, maintenance costs, and light pollution.

The goal of this project was to evaluate the best practices of a LED streetlight conversion,
and how these practices might be applied on Nantucket. We identified three project objectives:

1. Research best practices for converting current streetlighting to LED, including an
   evaluation of Massachusetts towns that have already converted to LED streetlighting.
2. Solicit input from stakeholders on Nantucket regarding possible conversion of the
   existing cobra-style HPS streetlights to LEDs.
3. Develop a recommended set of processes and policies for the implementation of a LED
   conversion based on the findings from objective 1 and 2.

To accomplish this goal and meet these objectives, we interviewed town administrators in
several municipalities that had converted streetlights to LEDs as well as outdoor lighting
consultants and experts. We also interviewed various stakeholders on Nantucket to learn how the
best practices for LED streetlight conversions might or might not translate into the island setting.
Using this information, we developed a set of recommendations for the Town of Nantucket to
utilize as a road map for their LED streetlight conversion.

Major Research Findings
Nationally, the United States is expected to invest approximately 8.2 billion dollars in
LED streetlighting throughout the next decade (“Interest in smart streetlighting triples in US
cities”, 2020). Cities find energy reductions in their streetlighting of up to 80% with a 66%
average (“Interest in smart streetlighting triples in US cities”, 2020). To look specifically at
Massachusetts, through interviews with the Cape Light Compact (CLC) and the Metropolitan
Area Planning Council (MAPC), two regional planning authorities in Cape Cod and the Greater
Boston respectively, we learned the primary motivations for towns to convert their streetlights to
LED, as well as the general path that most municipalities take in their streetlight conversion
process. Additionally, we spoke with several lighting consultant companies to see how their
services assist towns in performing the most effective streetlight conversion possible.

We found that towns in the Cape Cod region typically reduced costs by ~75% following
installation of LED streetlights and shifted to annual rather than monthly service schedules.
Additionally, light pollution levels decreased, even in the most populated downtown areas. We
learned that this was accomplished through effective lighting design, choosing lighting fixtures
with an appropriate BUG¹ rating for the area, as well as a sufficient correlated color temperature
(CCT). MAPC representatives, indicated that many communities have installed lighting control
systems to dim the lights during some hours of the night. Such controls reduce light pollution
and energy consumption and give towns the ability to better adjust lighting to residents’ needs.

Recommendations
Based on our research findings, we identified a set of recommendations and best practices.
Some of these actions can be conducted in parallel, and others will need to be implemented
sequentially.

1. We recommend the Town of Nantucket create an LED streetlight working group to
   facilitate major aspects of the conversion process. This will allow Nantucket to easily
   gain insight from key stakeholder groups in the community as well as serve as a primary
   decision-making body.
2. Hire a streetlighting conversion consultant to assist throughout and after the
   conversion process. By having an expert throughout the conversion process, Nantucket
   can be confident in their actions throughout the entire conversion process. The
   streetlighting consultant can help with the following tasks:
   1. Performing an exhaustive GIS audit of all the streetlights on Nantucket.
      Presently, there is no complete or comprehensive audit of the town streetlights,
      but this is a necessary first step in the conversion process.
   2. Conduct an economic analysis of the LED streetlight conversion process. An
      economic analysis will reveal the best options the town should pursue in terms of
      system design, including choice of hardware and software, and installation and
      maintenance options.
   3. Purchasing the streetlights from National Grid. Purchasing the existing
      streetlights gives Nantucket autonomy and independence in its conversion
      process, allowing the town to utilize a more granular approach rather than a
      blanket solution.
   4. Creating a budget for the entire LED streetlight conversion process using the
      economic analysis. Having a budget determined and approved by the Town of
      Nantucket is a necessary step in the conversion process.

In implementing the LED streetlight conversion, the Town of Nantucket must conduct
the following logistical tasks:

3. Conduct a pilot demonstration of LED streetlights to solicit public feedback on light
   fixture design and features. This gives the general public insight into the conversion
   process, and lets them provide input on factors such as CCT, brightness, and fixture style
4. Install the streetlights based upon the feedback from the pilot demonstration. The
   lighting consultant can help the town negotiate to find a contractor to perform the
   installation process as well as interim maintenance.
5. Obtain a maintenance contractor for the interim period of the conversion and
   afterwards. Most towns see a maintenance contractor come once a year to replace the
   lights. Having an established relationship with a contractor starts this process.

When choosing lighting fixtures for the LED streetlight conversion, we recommend the
following tasks:

6. Obtain streetlight fixtures at 2200K that effectively direct light to only the area
   necessary. A dark sky compliant sky mitigates light pollution and is effective for lighting
7. Install lighting controls on the LED streetlighting fixtures to reduce energy
   consumption and light pollution. This will allow for an effective way for the streetlights
   to be dimmed, reducing energy consumption. Additionally, remotely controlling the
   streetlights can be an effective way to implement resident feedback regarding streetlights.
8. Dim the streetlights at night or when not in use to mitigate light pollution and
   energy consumption. This will further reduce light pollution as well as energy
   consumption.

Lastly, the town should consider the following items:

9. Implement a system for residential feedback. This will allow the town to learn where
   extra lighting may be needed, where lights need to be removed, and were lighting shields
   should be installed through efficient resident engagement
10. Develop a relationship with a larger regional planning organization. This will
    provide Nantucket with closer access to a community able to provide their experiences in
    their streetlight conversion process.

By following these recommendations, we believe the Town of Nantucket can ensure that
the streetlight conversion process is accomplished in a timely, effective, and cost-effective
fashion.

¹The backlight, uplight, and glare (BUG) rating indicates if the fixture is dark sky compliant.