Hawaii County is moving forward on the final phase of converting 10,000 street lights to energy-saving light-emitting diode, or LED, lights.
The Hawaii County Council is scheduled Friday to appropriate $2 million to finish the project, which began on an experimental basis in 2012.
From the mid-1980s, most outdoor streetlights were required by law to be of the low-pressure sodium variety. Those are favored by astronomers in the islands’ observatories because they don’t interfere as much with visibility in the night sky.
But in 2011, the County Council approved a bill that allowed the conversion to brighter, more efficient LED lights. The county so far has installed about 600 of the LED lights in Hilo, abut 300 in Kona and 100 in Waimea, said Traffic Division Chief Ron Thiel.
The lights are yellowish-green instead of the yellow the old low-pressure sodium lights emitted. Thiel thinks they’re safer, because they aren’t as easy to confuse with amber caution lights.
“We’re trying to keep the same brightness, but it’s downward light and not nearly as glaring so you don’t have the light shining in your eyes,” Thiel said, “so it doesn’t appear as bright.”
Another 80 LED lights are about to be installed in Alii Heights to see how they do in residential districts, he added.
Thiel said once all the LED lights are installed, likely by the end of 2016, the county will save about $1 million a year on its electric bill. The entire project is slated to cost about $4 million, with some of the money coming from state and federal grants.
Hamakua Councilwoman Valerie Poindexter said Thiel had given the council a presentation about the new lights, and she thinks they will be an improvement.
“It’s going to be better than what we have,” Poindexter said.
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 needed 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.
Ron Laub, the University of Hawaii Institute for Astronomy’s light control specialist, said astronomers prefer the low-pressure sodium lights but can accept the switch to the LEDs with the use of filters that would eliminate all but 2 percent of the blue light emitted from the bulbs.
“We’ve been working very closely with the astronomers,” Thiel said Wednesday.