Questions in Dublin, Ireland about glare from 4000K LEDs
Dublin’s New Street Lights Save on Energy But Add Some Glare
The streetlamp outside the window of Cathal Eochagáin’s home office used to pop into a red glow at dusk and fade slowly to orange as night fell. In September 2020, the light was replaced, Eochagáin said. The orange radiance that used to spread over the street in Ranelagh was swapped for a bright white-blue beam that points more directly at the footpath – and also straight into Eochagáin’s home. They save on electricity, said Eochagáin, on Friday. The new street lights are so bright that it lights the room in the evenings.
“My girlfriend has also used the light from the street light to help put make-up on because it’s better lighting than our ceiling light,” they said.
Since 2016, Dublin City Council has been replacing the low-pressure sodium bulbs that lit up the city streets, with more energy-efficient light-emitting diodes (LEDs). Public lighting is a big energy user in the city, responsible for 24 percent (the largest single chunk) of the council’s total energy consumption. So when the “orange” light fitting cannot be maintained anymore, the council has been installing cheaper and more energy-saving LED lights.
But they’re pretty bright, too.
Lighting the City
A review in 2019 of Dublin City Council’s energy use by Codema, Dublin’s energy agency, found that public lighting was a major guzzler of energy, accounting for 24 percent of its primary energy consumption. In roughly the ten years up to the end of 2019, public lighting has improved its energy performance by 26 percent, the report said. The council has swapped in around 9,300 or so LED bulbs so far and plans to keep replacing the rest of its 47,000 street lamps, the report says, with a target of up to 8,000 lamps a year.
“Energy reduction in electricity has more impact on the council’s targets [for energy efficiency and CO2] than any other energy type, due to its high primary energy conversion factor,” says the report.
The new LED lamps are “highly energy-efficient and they contribute significantly to reducing carbon emissions”, said a spokesperson for Dublin City Council.
“From an energy-savings point of view, it’s no question it’s ecologically beneficial to have low-energy lighting,” said Michael Pidgeon, a Green Party councilor, who chairs the council’s environment and energy committee.“
The lights use a quarter of what the previous bulbs used,” he said. Other local authorities may have underused roads or farmlands that they don’t have to brighten, he says. But “in Dublin, every piece needs to be lit”.
Living With It
“If we didn’t have good blinds, it would be impossible to sleep. It’s really intense,” says Eoin Harford, who lives and works in an estate in Clonsilla, where his street has white LED lights. (His local council is Fingal County Council.) According to Dublin City Council, the color temperature of its new lamps is 4,000 kelvin. That level of light can affect your sleep at night, says Harvard researcher and neuroscientist Dr. Steven Lockley.
“The sodium lights are quite dim, but you can’t see the color under them very well,” he says.
“So, for a long time police have been concerned about those types of lights because you can’t see the colors of cars or coats, for example,” says Dr. Lockley, who researches sleep at the Brigham and Women’s Hospital in Cambridge, Massachusetts.
About 20 years ago now, a receptor was discovered in the eye that is more sensitive to blue light, he says. “This part of the eye goes straight to the body clock which controls our 24-hour rhythms.” He said that 4,000 Kelvin isn’t particularly blue. “So the council has already taken that into account, but we really need to measure the intensity to know for sure.”
It would be useful to know the spectrum and intensity of the council’s new LED lights, to tell how alert it would make people, he said. When asked, the council spokesperson pointed to the color temperature of 4,000 kelvin. But Dr. Lockley said that doesn’t tell the full story of its effect on sleep.
“If I want to increase your alertness, I can give you blue light. If I want to make you sleepy, I can give you redder-looking light,” said Dr. Lockley. If the council were to switch the color from blue or white, to yellow, would this make a gentler light into people’s homes?
“I don’t know. It depends on the intensity, you need to measure it and know the intensity of the light,” he said.
A Few Tweaks
Mannix Flynn, an independent councilor, said residents have complained to him that the white lighting is too harsh for residential areas.
“It looks like you’re in a compound. A number of people notice that the light looks wrong. It blends and bleaches out everything,” he says. “The orange glow gives a lovely atmosphere.”
Dublin City Council “needs to have a serious consideration, and areas need to be assessed to appropriate lighting in terms of buildings”, he said. Harford says he’d like lights like the rest of his Clonsilla estate, the orange ones. “There’s a massive difference between warm and cold light.” Or dimmer lighting angled downwards would help, he says. “Although that might be pie in the sky. If they just changed the color to orange, I’d be happy.”
“I know orange light is synonymous with the city,” said John Lyons, an independent councilor. “It’s a bit of an adjustment, but in time everyone will get used to it.” The change has to happen though for the council to meet climate targets, he said. “If there are minor issues, they can be explored, but overall we have to support the transition.”
Dr. Lockley also said a dimmer may help. It could halve the intensity of the light as the night progresses, he said, reducing light pollution and being kinder to wildlife. “If the streetlight is right outside your window, then the council should come and put a shade in the way. It’s not hard to do – you still get the light on the street, which is where you want it,” he said. Dublin City Council hasn’t responded yet to a question about installing such shades. That said, indoor light affects sleep more than outdoor light, says Dr. Lockley. “People should be aware of their phone, laptop, television, and light usage before sleep.”
Reading with a dim night light before bed is about what the eye can handle before going to sleep, he says. “If you are concerned about street lighting affecting sleep, then use blackout curtains or wear an eye mask. It can be solved very easily,” he said.
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