It won’t be “quite the difference” between night and day along city streets, but you’ll notice the improvements.
Casa Grande is entering into a contract to replace streetlights with LED fixtures, abandoning the high-vapor sodium ones that have been here for years.
There are more than 6,000 street lights in Casa Grande, with electricity provided mostly by APS, but also Electrical District 2 and San Carlos Irrigation District (east of Interstate 10). This project includes only the lights powered by APS.
“The goal for the LED street lights is to improve energy efficiency and save energy and dollars through correct sizing and lighting levels,” Senior Management Analyst Steven Turner told the City Council.
Eventually, he said, all lights will be connected to a system that will allow dimming or brightening, depending upon a given situation.
Ameresco, the company working with the city and the one that oversaw solar lighting at parking facilities, has recommended that the adaptive lighting system be tested on 70 fixtures along the route of the annual Electric Light Parade
Using that adaptive control system, Turner said, “We can dim the lights so people have a better viewing of the parade itself.”
In the future, he added, “All 3,867 fixtures will have the capability to interface with the citywide wireless control. That control system allows the different lighting to be dimmed or brightened or turned off or on. It can also be used to brighten during traffic accidents or during a lighting failure. If a pole gets knocked down, we can brighten the lights next to that light to make sure there’s adequate light for that area.”
He continued, “When Ameresco did the study session a few months ago, they talked about the potential for better response of public safety, because if you’re trying to find a black car or blue car or green car, with the high pressure sodium, they make it look like the same exact color, but with this LED street technology you’ll be able to differentiate the colors a little bit better.”
It’s a situation of both money and energy savings.
According to the presentation, conversion would cut energy consumption by 68 percent.
The cost now for electricity for the 3,867 streetlights is $307,016, the staff report says, and the cost of maintenance is $2.35 per pole per month, or $109,049.40 per year.
“The LED streetlights are 100,000-hour fixtures with a 10-year manufacturer’s warranty,” the staff report continues. “The expected life of each fixture is almost 24 years. The proposed project reduces the streetlight energy consumption by 68 percent and the billed utility costs are reduced by over 39 percent.”
The billed costs, Turner told the council, are lower than the energy savings “because there are some fixed costs that APS charges that we simply cannot avoid at this time.”
Turner added, “Over the first 10 years, they’re predicting 35 failures. That’s three-and-a-half lights. We could look into providing the maintenance in-house and reducing the maintenance cost significantly.”
The staff report gives the following financial breakdown:
- Total financed project cost – $1,689,249
- Estimated utility rebate – $215,726
- Finance term – 15 years
- Finance interest rate – 2 percent
- 20-year benefit (energy and maintenance) – $3,139,589, broken down as maintenance benefit of $2,035,884 and electricity benefit of $1,103,987.
- The city is paying for the project from the general fund as a loan with 2 percent interest. The savings from the project in the Highway User Revenue Fund, which covers streets projects, will be used to repay the general fund.
“The amount of light removed from the environment is over 65 percent and that’s because the light quality from these new fixtures is over 250 percent better than the high-pressure sodiums that we currently have,” Turner told the council. “The LED street lighting has a color rendering index of 70. To give a little perspective, on the scale of one to 100, with a 100 being full sunlight, the current streetlights have a color rendering index of 25, so it’s a significantly better quality lighting that we are proposing to change these fixtures to.”
Turner continued, “With dark sky complaints, a lot of articles were put out … that talked about potential harm of changing to LED street lights. But both the International Dark Sky Association and the American Medical Association recommend using a 3,000 Kelvin color temperature to minimize potential harm to human health effects and also protect the astronomical community, and that’s what we’re proposing to use in our project as well. I also received an e-mail from the Steward Observatory from the University of Arizona thanking us for considering the 3,000 Kelvin color temperature.”
He added, “It’s something that we’ve been mindful of. We want to make sure that we’re not brightening the sky or doing damage to our residents. We want to make sure that we are well within the recommendations of both the Dark Sky Association and the American Medical Association.”
As Mayor Bob Jackson sees it, “I’m old enough that I remember when they had mercury vapor lights and they converted them all to high-pressure sodium and they went through the same thing. And they paid for those conversions with the savings on the light. It’s just that technology has improved so much, the LED is the next generation.”
He continued, “I know that we’ve got probably another 2,500 streetlights that we don’t own, but it would sure be nice if we work with those providers, be it ED2 or Hohokam or San Carlos, to see if they would be interested in converting those, as well, just so that there’s some continuity and maybe there’s some additional savings there that we could realize, even if we had to share it with them. I just suggest that, but (let’s) see what we can do about it.