Lighting that emits too much light or shines when and where it’s not needed is wasteful. Wasting energy has huge economic and environmental consequences.
In an average year in the U.S. alone, outdoor lighting uses about 120 terawatt-hours of energy, mostly to illuminate streets and parking lots. That’s enough energy to meet New York City’s total electricity needs for two years!
IDA estimates that least 30 percent of all outdoor lighting in the U.S. alone is wasted, mostly by lights that aren’t shielded. That adds up to $3.3 billion and the release of 21 million tons of carbon dioxide per year! To offset all that carbon dioxide, we’d have to plant 875 million trees annually.
Environmental responsibility requires energy efficiency and conservation:
- Installing quality outdoor lighting could cut energy use by 60–70 percent, save billions of dollars and cut carbon emissions.
- Outdoor lighting should be fully shielded and direct light down where it is needed, not into the sky.
- Fully shielded fixtures can provide the same level of illumination on the ground as unshielded ones, but with less energy and cost.
- Unnecessary indoor lighting – particularly in empty office buildings at night – should be turned off.
New lighting technologies can help conserve energy
- LEDs and compact fluorescents (CFLs) can help reduce energy use and protect the environment, but only warm-white bulbs should be used.
- Dimmers, motion sensors and timers can help to reduce average illumination levels and save even more energy.
Quality lighting design reduces energy use and therefore energy dependence. It also reduces carbon emissions, saves money and allows us to enjoy the night sky.
Hong Kong is one of the world's worst cities for light pollution with night skies around 1,000 times brighter than globally accepted levels, researchers said Wednesday ahead of this year's Earth Hour event.
The densely-populated city of seven million inhabitants, full of residential highrises, towering office blocks and neon advertisements, has no laws to control external lighting.
The result, researchers say, is that light pollution is thought to be much worse than in other large cities, including London, Sydney, Tokyo and Shanghai.
"In Hong Kong, you cannot go anywhere outdoor in the evening without your eyes being blinded by this really intrusive outdoor lighting," the light pollution survey's head Jason Pun told AFP.
"The fact that we have all this light in the sky means energy is wasted," he said, adding that excessive artificial lighting also adversely affects nocturnal wildlife.
Lights Out: What SF, NYC, And Tokyo Would Look Like Under Montana's Stars
City living is a series of compromises—we give up one thing to enjoy another. But Darkened Skies, a series by French photographer Thierry Cohen, shows us something we might not even realize is missing: the stars.
Cohen starts by shooting magnificent images of night skies in places like rural Montana and the Sahara. Then, he matches each photograph to a megacity on the same latitude, layering them into a single photo. So Darkened Skies doesn’t just show us the Milky Way randomly inserted behind the Manhattan Skyline; it shows us the exact piece of sky that we’d be able to see if not for light pollution. The critic Francis Hodgson explains:
There is an urban mythology, which is already old, in which the city teems with energy and illumines everything around it. All roads lead to Rome, we were told. Cohen is telling us the opposite. It is impossible not to read these pictures the way the artist wants them read: cold, cold cities below, cut off from the seemingly infinite energies above. It’s a powerful reversal, and one very much in tune with a wave of environmental thinking of the moment.