Hundreds of new, lime-green LED streetlights in Waimea and Hilo are the vanguard of an islandwide conversion from the low-pressure sodium lights that have been an island staple for decades.
To date, the county has installed 100 streetlights in Waimea and 500 in Hilo, with plans to install the remaining 400 in Kailua-Kona. The lights have been purchased with a $500,000 federal grant.
The county Department of Public Works’ Traffic Division is drafting an amendment to the lighting code that would allow the conversion of streetlights to continue on all county roads, with energy savings of around 60 percent compared to low-pressure sodium lights.
If the new code is approved, the county will replace nearly 9,000 streetlights at a cost between $3 million and $4 million.
The cost of the individual LEDs fluctuates, said Traffic Division chief Ron Thiel, so he could only provide a ballpark figure. In 2011, he estimated the lights might cost between $500 and $1,800, but recently the cost has come down to around $300.
From the mid-1980s most outdoor streetlights were required by law to be of the low-pressure sodium variety. But last year, the County Council approved a bill that allowed the conversion to brighter, more efficient light-emitting diode lights.
Low-pressure sodium lamps are favored by the astronomy community because their light emissions fall within a very narrow region of the amber-orange visible spectrum, leaving most of the other visible light frequencies untouched. Other light sources, including incandescents and white LEDs, spread out their emissions over a much broader portion of the visible spectrum, causing interference for astronomers and forcing them to increase the amount of time for observations.
But while monochromatic low-pressure sodium lights are ideal for observing the heavens, they aren’t as safe for drivers who rely on them to navigate Big Island roadways.
The astronomers have accepted the increase in blue light from the LED sources.
“It’s a little more blue light, but not very much,” Thiel said.
