NorthWestern Energy LED Streetlight Replacement Project
In June 2020, NorthWestern Energy began work in Missoula to replace streetlight lamps in Streetlight Improvement Districts (SLIDs) with light emitting diode (LED) lamp heads. The streetlights currently in place use high-pressure sodium (HPS) bulbs, which are becoming more difficult for NorthWestern Energy to purchase, and they use about 50 percent more electricity than the LED bulbs that will replace them.
Benefits to Missoula citizens include:
- Better lighting on streets and sidewalks for improved vehicle and pedestrian safety,
- Lower energy costs for property owners in SLIDs,
- Less electricity used, and
- Better directed lighting. The new fixtures shine light downward to the street and sidewalk better than the old bulbs.
City Lighting Ordinance Compliance
The new LED streetlight fixtures are rated as "dark sky approved," which according to the International Dark Sky Association means they minimize glare while reducing light trespass and sky glow. The City asked NorthWestern Energy to conduct nighttime streetlight output measurements in two test areas (Stoddard St. and Fairview Ave.) to ensure the new light fixtures comply with the City’s lighting ordinance (MMC 8.64, Missoula Outdoor Lighting Ordinance). Light measurements taken by NorthWestern Energy in the test areas were duplicated by City staff and found to be in compliance with the lighting ordinance.
For updates on which neighborhoods are next for streetlight LED replacements, visit the City’s Weekly Road Report.
Please note: The City’s streetlight crew will also be out replacing old high-pressure sodium bulbs with LEDs in City-owned streetlights that are not in a streetlight improvement district.
If you have a problem with a new LED streetlight or have questions about the project, please contact NorthWestern Energy’s Steve Clawson at (406) 544-1056 or Stephen.Clawson@northwestern.com.
Before and after comparisons within test areas.
Fairview Ave. HPS #1
HPS fixture street view with ~2200K “orange” color temperature. Shadows due to tree growth blocking some light. Trimming trees to prevent unintended shadows is not part of project.
Fairview Ave. LED #1
Notice lack of up-light and better light control—light behind fixture is minimized.
Fairview Ave. HPS #2
HPS fixture has undesirable up-light and more back light behind fixture, with excess light washing onto face of house.
Fairview Ave. LED #2
Notice lack of up-light and street is well lit. These are “soft white” 2700K color temperature fixtures that provide good color rendition without the intense blue light of much higher color temperature fixtures.
Stoddard St. HPS #1
HPS fixture with more back light than ideal.
Stoddard St. LED #1
LED fixture with better light control and less back light.
Stoddard St. Mix
HPS fixtures in background and new LED fixtures in foreground. Notice contrast in up-light, glare off of fixtures, and color temperature.