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Light pollution wastes energy and money and damages the climate

London from the air at night. Credit: Shutterstock

Lighting levels that are higher than necessary and light that 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!

DarkSky 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 to 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, preventing leakage of that light into the night sky.

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. Learn more about LEDs and correlated color temperature (CCT) from our LED Practical Guide.
  • 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. Watch a clip of the documentary The City Dark to learn how lighting design can reduce light pollution and conserve energy: