Everyone loves a beautiful night sky—crisp, clear, and with millions of visible stars. However, we seldom experience this wonder because, most of the time, the area we are in is so bright it pollutes the sky and makes the galaxies invisible.

The International Dark-Sky Association

To try to solve all that, the International Dark-Sky Association (IDA) exists. It’s a 501(c)(3) started in 1988. Their mission is to preserve the night skies for not only those of us living in the present time, but also for our future generations. They aim to be educators of the public and policy makers about conservation and protection of the night sky. They also promote environmentally responsible lighting outside and empower others with the tools and resources to help restore the night sky to what it once was.

Light pollution is essentially inappropriate usage of light during the nighttime hours. The IDA is a recognized authority that is working to identify and publicize the negative effects of such artificial light on climate change, wildlife, and human health. It doesn’t stop there though, they not only work with the public but also with city planners, lighting manufacturers, parks, protected areas, and legislators to create better lighting options. The public outreach in and of itself provides solutions, education, and programs that communicate these things to everyone (not only in the U.S., but also throughout the world).

Where Are We Going Wrong?

In general, we waste a lot of light. This happens when too much is shining when or where it isn’t useful. Not only are there environmental consequences, it’s also expensive.

On average, the United States uses around 120 terawatt-hours of energy to light its streets and parking lots (mostly, among other things). To give you an idea of how much this actually is, consider this—that amount of energy could meet the needs of New York City for two whole years!

It is estimated that 30% of all outdoor lighting in just the United States is wasted. Most of this is caused by unshielded lighting. This affects our health by adding 21 million tons of carbon dioxide to the air annually, which could only be fixed if we planted some 875 million trees each year. Not only is this horrible for our bodies, it is also costing us a huge sum of money—$3.3 billion to be exact.

How To Fix It

It’s actually a pretty simple solution. It only takes two things—energy efficiency and conservation. Practically though, there are a few things you can do. Getting good quality outdoor lighting can cut energy use by 60-70%, while saving billions of dollars and reducing carbon emissions. Additionally, you should get lighting that is shielded from the sky and shines directly down. These fixtures can provide the same amount of illumination and save energy and money at the same time. Finally, if the lights inside a building (such as an office) don’t have to be on at night so simply turn them off.

What Kind of Lights Should I Use?

LEDs and compact fluorescents (CFLs) are good options. They both use less energy and help protect the environment. However, if you use them, only use the warm-white bulbs. You can lessen the level of brightness and conserve even more energy by installing dimmers, motion sensors, and timers.

While it is necessary to have outdoor lighting for purposes such as safety and commerce, it’s also essential that it is used wisely. To help avoid light pollution, consider the following list of tips.

• Only have the light on when it needs to be
• Only illuminate the space that needs it
• Make it only as bright as it has to be
• Lessen blue light emissions
• Make sure it’s fully shielded (only pointing down)

There are some fixtures that are really great to use and others that simply should be off-limits.

In general, those that are unacceptable and/or discouraged are fixtures that produce glare and light trespass. Examples of this are unshielded or poorly-shielded floodlights, unshielded wallpacks, unshielded or poorly-shielded wall mount fixtures, drop-lens and sag-lens fixtures with exposed bulb/refractor lens, unshielded streetlights, unshielded bollards, unshielded barn lights, louvered “marine” style fixtures, unshielded “period” style fixtures, unshielded PAR floodlights, and drop-lens canopy fixtures.

Likewise, normally the fixtures that are acceptable are those that shield the light source to minimize glare and light trespass, facilitating better vision at night. Flat lens, full cutoff fixtures, fully shielded wallpack and wall mount fixtures, fully shielded fixtures, full cutoff streetlights, fully shielded barn lights, fully shielded walkway bollards, fully shielded decorative fixtures, fully shielded “period” style fixtures, shielded/poorly-aimed PAR floodlights, and flush mounted or side shielded under canopy fixtures are all good options.

More About the Lamps

Many people are familiar with incandescent and fluorescent bulbs as they are commonly used as indoor lighting. However, outdoor lighting usually has a more industrial feel. Some typical sources are low-pressure sodium (“LPS”), high-pressure sodium (“HPS”), metal halide, and light emitting diodes (“LEDs”).

LPS are energy efficient and a great option for lighting near astronomical observatories and some locations that are environmentally sensitive. The only downside of these is that they give off a narrow spectrum of pumpkin-colored light that some people aren’t too fond of.

HPS are used for street lighting in cities. The color is still somewhat orange but is more “true to life” than the coloring of LPS.

If you want a white light, you have two options—metal halide and LEDs. The plus side of LEDs is the fact that they can be dimmed. That way if the parking lot or empty street isn’t being used, they can be turned to a lower brightness or completely off and then back on when the place is in use again. This, of course, reduces light pollution and saves energy. They also last a long time and are becoming increasingly more common in cities, replacing old lighting. It’s important to research before replacing existing lighting though, as there are things you should consider first.

The Color of the Light Matters

We’ve established that it’s wise to have lighting that is fully shielded, but another thing that’s important is the color of the light. This is because there’s a lot of blue in the spectrum of LED and metal halide fixtures. The issue with this is that blue light actually does more damage to the sky than the other colors. Because of this, you’ll want to minimize the amount of light emitted. In addition, blue light is both bad for human health and endangering to wildlife. Therefore, IDA recommends that the lighting you use has a color temperature of no more than 3000 Kelvins. The lower the color temperature, the warmer the color is. However, the higher color temperatures produce the “colder” blue light. That said, it’s a good idea to use only warm sources of light for the outdoors. Some good options are LPS, HPS, and the low-color-temperature LEDs. You’d need to be careful with those though because even the low-color-temperature LEDs’ white light can be a threat to the nighttime environment. If so, use an LPS or narrow-spectrum LED.

The image above shows how much light is used by the different areas of the world.

Photo credits to the IDA: International Dark-Sky Association.