LED Streetlight Conversion FAQs

Sustainability Director

Erin Gill
egill@knoxvilletn.gov
(865) 215-4430

400 Main St., Room 503
Knoxville, TN 37902

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City of Knoxville LED Streetlight Conversion FAQs


1. What is the purpose and scope of this project?
By converting streetlights from high-pressure sodium (HPS) bulbs to light-emitting diode (LED) technology, the City will save energy, save money, and improve and modernize the streetlight system. 
Historically, the City of Knoxville has spent more than $4 million annually to cover the energy, operations and maintenance costs associated with the City's nearly 30,000 street lights. By converting these HPS lights to modern LED technology, the City will significantly reduce energy consumption and reduced maintenance costs.

As a result of the conversion, the City expects to reduce streetlight energy consumption by more than 65 percent, which will save more than $1 million each year.  Factoring in the ongoing cost of maintenance, the total net savings are expected to exceed $2 million annually relative to the City’s historic streetlight bill. 


2. What are the other benefits of this project?

The lifespan of LEDs is far longer than existing HPS streetlights. New LED fixtures are warrantied for 10 years and rated to maintain at least 70 percent of their light output for 100,000 hours (about 20 years).  The vast majority of lights will be full cutoff "nighttime friendly" fixtures that emit no light upward, thereby helping reduce light pollution.  

Because they use less energy, LEDs also help to reduce greenhouse gas emissions. Switching to LED streetlights will reduce the City’s greenhouse gas emissions by more than 13,000 metric tons of carbon dioxide per year, which will help the City achieve its goal to reduce municipal greenhouse gas reductions 20 percent by 2020 relative to 2005. 

The new LEDs provide a crisp, bright light that improves visibility and color rendition, making it easier for drivers to spot pedestrians or other obstructions in the roadway. 


3. What does “color temperature” mean? What is the color temperature of the new LEDs?

Color temperature of lighting is measured in Kelvin (K) units. Lower temperatures are warmer and yellower; higher temperatures are cooler and bluer. Our existing HPS streetlights have a color temperature of 2200K.  The new LED streetlights installed during this project have a color temperature of 3000K, a warm white that is similar to the “soft white” light color of an incandescent light bulb.  

In selecting the color temperature of the new LEDs, the City prioritized the recommendations of groups such as the International Dark Sky Alliance and American Medical Association, which recommend an LED color temperature of 3000K or less in order to minimize impacts on nocturnal wildlife, reduce glare and sky glow, and improve nightscapes.


4. What does “full cutoff” mean? Are the new LED’s full cutoff? 


The vast majority of new lights are full cutoff fixtures, meaning that light is directed downward to illuminate the street instead of shining upwards and illuminating the environment around the fixture. Full cutoff design helps provide a smooth transition from the brightest area of light directly under a lamp to the dimmest area between lamps. In addition, LED streetlights are directed downward to reduce disability glare experienced by drivers. 

Full cutoff design also reduces spill of light into homes and properties, as most of the light is directed onto the street. However, if a homeowner reports that there is light coming directly into their home from the new LEDs, the homeowner can request that the city evaluate the light to see if it fits the criteria to have a shield installed to control the unwanted light. 


5. How do I request a house shield? 

In certain rare situations, such as elevation changes or heavily sloped roadways, a streetlight may shine too much light on your home.  In those situations, the City will evaluate to see if a shield may be used to control the light.  Citizens concerned about light trespass onto their home from the new lights should assess the impact for a few days.  If the new light continues to bother you, please contact 3-1-1 by phone or online to request an evaluation for a light shield.  


6. Will the new lights be able to be dimmed or wirelessly controlled?  

No. As part of the LED Streetlight Retrofit project, representatives of the City’s Office of Sustainability and Department of Engineering piloted and evaluated in detail an approximately $2.4 million option to install smart/connected lighting controls as part of the LED retrofit.  However, this option was not pursued. 

The new LED lights retain the option of installing such controls in the future through the use of a 7-pin photocell on each fixture. This 7-pin photocell provides extra “sockets” allowing the City to plug in controls or other technologies in the future should that become desirable and cost effective.


7. How can I track the progress of the retrofit?

Real-time map updates showing what lights have been converted to LED are available online at www.knoxvilletn.gov/LED. You can search for your address or zoom in to your neighborhood.  Lights that have already been converted show as blue dots; unconverted lights show as yellow dots. 


8. Who do I call to report a streetlight that is not working or is damaged?

Citizens are encouraged to contact 3-1-1 by phone or online to report a streetlight that is damaged or not working. Please see No. 10 below for information about distinguishing between streetlights and KUB Outdoor Private Lights. 


9. What companies are involved with the LED conversion and streetlight maintenance?

The City contracted with Siemens Mobility, Inc. to design and implement the LED project. Siemens crews began installing the lights in Fall 2018 and expect to complete the project in Summer 2019. Siemens has subcontracted with local companies Andrews Electric and Edwards Supply for significant portions of the project. 
Local engineering firm Fulghum, MacIndoe & Associates, Inc. is providing Inspection services. 

The City has also contracted with Service One, a local electrical firm, to maintain the streetlight system. 


10. How can I tell the difference between a City of Knoxville Streetlight and a KUB Outdoor Private Light?

The City’s streetlights primarily illuminate publicly owned streets and right of ways.  Most City of Knoxville streetlights will have a metal tag with a 4-6 digit number, similar to this: 

Tag on City streetlight

 Questions/comments about these City streetlights lights can be directed to 3-1-1.

In addition, KUB maintains a large network of Outdoor Private Lights, typically used to illuminate areas such as backyards, playgrounds, driveways, and other customer-owned areas.   Sometimes called “Light Watchmen,” most KUB Outdoor Private Lights have a metal tag with a 9-digit number preceded by “LW,” for example:

Tag on KUB streetlight

Questions/comments about KUB Outdoor Private Lights can be directed to KUB’s Customer Care at 865-524-2911. 

KUB is in the process of converting Outdoor Private Lights to LED.  Both 3-1-1 and KUB’s Customer Care can assist you in determining whether a light is City streetlight or an Outdoor Private Light.