Unused lights left on over night, such as those in office buildings, waste energy, for no reason. This type of illumination contributes to the general sky glow of the city as well as wasting energy. Being dark sky friendly does not mean ‘no light.’ It means using the light that you need for a particular task in the most efficient manner possible.
Light shining into the sky creates glare and is not being used effectively. Using fully shielded lighting (i.e. downward facing light that does not emit above the horizontal) 100% of the energy being put into the light is being put and used where it is needed, on the ground. This means the light on the ground will be that much brighter and you can use fewer lights at lower wattages to achieve the same illumination, without glare, you got while using unshielded lighting.
An estimated 30% of street lighting is wasted light; defined as light that shines up into the sky where it does no good. Based on this number, it is estimated that in the United States alone 22,000 gigawatt-hours a year are wasted. At a conservative average of $.10 per kilowatt-hour, the cost of that wasted energy is $2.2 billion a year – enough to annually fund a new mission to Mars. In other terms, 3.6 tons of coal or 12.9 million barrels of oil are wasted every year to produce this lost light.
This translates into an unnecessary annual release of over 15.5 million metric tons of greenhouse gases – that’s the equivalent to the amount released by seven years of electric usage of all the homes in the U.S. By simply shielding lights and lowering bulb wattage to a reasonable level the consequences of light pollution could be easily avoided and we would save quite a bit of money that could be useful elsewhere.
The easy solutions to these problems are:
- shield and lower the wattage of all outdoor lighting: Homeowners, businesses, and cities.
- Use only the light you need to get the job done.
- Look for IDA-approved ‘Fixture Seal of Approval’ fixtures at your local stores (Lowe’s has recently started carrying a wide variety of affordable, IDA-approved, dark sky friendly lighting)
The fight to end light pollution begins at your front door.
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Learn more about IDSWeek and the impacts light pollution, the artificial brightening of the night sky, has on safety, wildlife, energy waste, and human health at www.darksky.org.