Light pollution has become an increasing concern as development continues and along with that more lighting. To date, many communities have ignored the consequences of artificial light on the environment and human health. Now the implications of unregulated lighting are being understood. The solution is dark sky lighting, as dark sky lighting reduces the impact of artificial illumination on ecosystems, human well-being, and our ability to view the night sky.

Dark sky lighting refers to outdoor light fixtures designed to minimize light pollution by using light fixtures equipped with low Kelvin shielded LEDs that direct the light downward. The implementation of dark sky lighting standards not only benefits astronomical research, ecosystems, and the quality of life for humans by reducing glare and enabling a view of the night sky. The establishment of dark sky communities and dark sky parks in the USA and around the world showcases the growing interest in promoting sustainable and responsible lighting practices.

Dark sky lighting protects our view of the night sky

Dark sky lighting protects our view of the night sky

Understanding Dark Sky Lighting

What is dark sky lighting? Why do dark skies matter and who cares? This section delves into why it matters to all of including the living organisms we share our world with.

What Is Dark Sky Lighting?

Dark Sky Lighting refers to outdoor lighting fixtures and practices designed to minimize light pollution and its impact on the environment, wildlife, and human health. Dark sky compliant light fixtures are engineered to direct light downward, minimizing the amount of upward light that contributes to light pollution. By using proper shielding, color temperature, and brightness levels, dark sky lighting helps preserve the natural night environment and maintains the beauty of dark skies.

HEZE with 590nm LEDs is a dark sky compliant wall pack located in a Maine state park

HEZE with 590nm LEDs is a dark sky compliant wall pack located in a Maine state park

Light Pollution and Its Effects

Light pollution is the excessive and inappropriate use of artificial light, which has harmful consequences on the environment and human health. Effects of light pollution include:

  • Disruptions to ecosystems: Artificial light at night can disrupt the natural behaviors and biological cycles of wildlife, affecting their feeding, mating, and migration patterns.
  • Human health: Exposure to excessive lighting at night has been linked to sleep disorders, obesity, and even an increased risk of cancer.
  • Energy waste: Unnecessary lighting contributes to energy waste and increases greenhouse gas emissions.
  • Loss of night sky visibility: Light pollution affects our ability to view the night sky, making it difficult to observe stars, constellations, and other celestial phenomena.

To address these issues, organizations such as the International Dark Sky Association (IDA), now known as DarkSky, are dedicated to advocating for dark sky-friendly lighting and policies.

The International Dark Sky Association is Now DarkSky

DarkSky is a non-profit organization founded in 1988 to combat light pollution. DarkSky works to protect night skies for present and future generations by advocating for responsible outdoor lighting and promoting dark sky education and awareness. Some of their initiatives include:

  • Certifications: DarkSky recognizes and certifies dark sky places such as parks and communities that exhibit a commitment to preserving dark skies through strict lighting regulations and public outreach.
  • Guidelines: The organization provides guidelines and standards for outdoor lighting fixtures and practices aiming to minimize light pollution.
  • Education and outreach: DarkSky works to raise public awareness about the issue of light pollution and its consequences through educational materials, public events, and partnerships with other organizations.

By understanding the importance of dark sky lighting and the detrimental effects of light pollution, individuals, businesses, and communities can take steps to implement responsible lighting practices, protecting nature and preserving the beauty of our night skies.

The dark sky lighting project in the photos was undertaken by the Appalachian Mountain Club and the town of Greenville Maine. The Appalachian Mountain Club helped Greenville get a grant and worked with Access Fixtures to design and manufacture dark sky lighting that provided security, safe egress, and naturally protected nature and dark skies. The results speak for themselves.

High school gym before dark sky lighting

High school gym before dark sky lighting

High school gym with dark sky lighting

High school gym with dark sky lighting

Dark Sky Lighting Benefits

Dark sky lighting brings numerous advantages to both the environment and human society. In this section, we will explore the primary benefits of embracing dark sky lighting, focusing on three key areas: Environmental and Wildlife Conservation, Energy Efficiency and Cost Savings, and Improved Safety and Security.

Environmental and Wildlife Conservation

The reduction of artificial light at night has significant positive impacts on the environment. One main advantage of dark sky lighting is its role in preserving natural habitats and behavior patterns for nocturnal animals. Excessive artificial lighting can disorient wildlife, affecting their feeding, mating, and migration behaviors. By minimizing the impacts of nighttime lighting, dark sky initiatives help maintain the health and balance of ecosystems.

Another central environmental benefit of dark sky lighting is the preservation of night skies for astronomical observation. By limiting light pollution, dark sky regions enable clearer views of stars and celestial phenomena, which are not only of interest to professional and amateur astronomers but also contribute to cultural, educational, and touristic experiences.

Dark sky lighting will preserve our views of the stars

Dark sky lighting will preserve our views of the stars

Energy Efficiency and Cost Savings

Dark sky lighting also promotes energy efficiency using better-designed light fixtures and technologies. By directing light downward and minimizing glare, dark sky lighting helps reduce energy waste. This leads to cost savings for individuals, businesses, and municipalities that adhere to dark sky principles.

Implementing energy-efficient lighting, such as LEDs with appropriate color temperatures, further enhances the benefits of dark sky lighting. Reduced energy consumption not only cuts costs but also contributes to lower greenhouse gas emissions, supporting efforts to mitigate climate change.

What’s a watt worth? Use the chart on the right to determine what each watt of energy costs per year. For example, you can calculate the annual operating cost a 30 watt wall pack that is on 7 days per week for an average of 10 hour a day. 

Calculate what each watt of energy costs you each year

Calculate what each watt of energy used costs you each year

Improved Safety and Security

Contrary to the common belief that increased artificial lighting guarantees higher levels of safety and security, research has shown that excessive or poorly designed lighting can have negative effects. For instance, glare and light trespass caused by ineffective lighting can decrease visibility making it harder for residents and drivers to see potential hazards.

By optimizing the balance between illumination and darkness, dark sky lighting improves the overall quality of nighttime visibility. These measures create environments in which people can feel safe and secure, without unnecessary energy consumption or harm to the environment and wildlife.

For more information by Florida Atlantic Univeristy on how glare affects security, click here

Glare impacts the ability to see an intruder. Click to enlarge.

Glare impacts the ability to see an intruder. Click to enlarge. Photo by George Fleenor and published by the International Dark Sky Association.

Dark Sky Light Fixtures

Dark sky compliant light fixtures are designed and manufactured by integrating a number of features, including full cutoff design, shielding, optics, and low Kelvin LEDs. One measure of dark sky performance is a BUG rating.

Full Cutoff Fixtures

Full cutoff light fixtures are the first step in being dark sky compliant. Full cutoff light fixtures have the light source, typically LEDs, up inside the light fixture preventing the light from going up or skyward. This way the the LEDs are somewhat or completely obscured from the view of humans and wildlife. Full cutoff light fixture designs also have the lens above the lowest part of the fixture housing, reducing glare and eliminating uplight.

The images on the right show the difference between traditional wall packs and full cutoff wall packs that reduces uplight and glare.

Comparing traditional and full cutoff LED wall packs

Comparing traditional and full cutoff LED wall packs

LEDs and Color Temperature

When selecting dark sky compliant lighting, it is important to consider the LED temperature, which is measured in Kelvin (K), or in some instances the nanometers (nm). Lower color temperatures emit warmer light, while higher temperatures produce a cooler bluer light. Dark sky compliance typically requires 3000 Kelvin or lower, but lower Kelvin is preferred. Many dark sky communities have ordinances that require 2700 Kelvin, 2200 Kelvin, or even specific LEDs measured in nanometers. For example, most oceanfront communities in the southeast USA require 590nm Amber LEDs in full cutoff light fixtures to protect sea turtle hatchlings.

Kelvin Temperatures of 1000 Kelvin to 10000 Kelvin

Kelvin Temperatures of 1000 Kelvin to 10000 Kelvin.

Optics

Optics impact the performance of full cutoff light fixtures. If the optics, such as a lens drops below the housing of the light fixture, the fixture will probably not be dark sky compliant. If compliance is determined via a BUG rating, the dropdown lens will cause the BUG rating to be insufficient. Optics, more often enhance the performance of the dark sky compliant fixture. The optics do not need to drop below the fixture housing to distribute the light. Using LEDs and high-performance optics in a full cutoff light fixture, the light can be distributed precisely where it is wanted or needed.

APTO Dark Sky Full Cutoff Wall Pack with 2200 Kelvin LEDs Type IV Optics

APTO Dark Sky Full Cutoff Wall Pack with 2200 Kelvin LEDs Type IV Optics

Shields and Accessories 

Shields and accessories can further enhance the performance of dark sky compliant fixtures by providing additional light control. Shields, in addition to optics, can help direct light output and reduce unwanted spillage to neighboring properties. More typically, shields are used to block light in one direction or to partially obscure the light source in a light fixture. Some new shield designs are extremely effective and were developed to obscure one or two LEDs.

Other accessories or requirements for dark sky compliant lighting, depending on local lighting ordinances, are fixed arm mounts. Fixed arm mounts force the light fixture to remain horizontal to the ground and are not able to be tilted. Again, with the correct optics, pointing the light fixture and projecting the light is rarely needed.

Shielding one or two LEDs is a new way to obscure the light source and minimize glare

Shielding one or two LEDs is a new way to obscure the light source and minimize glare

Design and Ordinances for Dark Sky Compliance

Dark sky ordinances or compliance can differ from community to community. The differences may be due to objectives like protecting the night sky for telescopes such as in Hawaii or Flagstaff Arizona, protecting sea turtle hatchlings in Florida, or protecting one of the darkest places remaining on the east coast of the USA. What are some of the objectives of dark sky lighting? What are some of the criteria that determine if the lighting is dark sky compliant?

BUG Rating – Back Light, Up Light, and Glare

BUG is a measurement of back light, uplight, and glare. Some or too much of any of the three makes for poor lighting, which is typically regulated as part of dark sky compliance.  Many dark sky lighting ordinances specify the BUG rating.

  • Back Light – Back light is the light emitted behind the light fixture. It is not always a consideration in dark sky lighting ordinances. For example, it would be desirable for light to be emitted 360° in a park setting for egress and safety. Back light is unacceptable on a beach where sea turtle hatchlings would be or where the light is going into the windows of housing units.
  • Uplight – Uplight is the light emitted going up and that is never acceptable. Sometimes a little light reflecting up off part of the fixture, such as off a dark part of a bollard light is acceptable, but uplight off of a reflector or due to inept optics is rarely if ever acceptable.
  • Glare – Glare is extreme or strong brightness in a visual field. It inhibits good vision and eliminates contrast. Glare is easy to eliminate and is never acceptable in dark sky ordinances. If a fixture is a full cutoff light fixture, chances are the glare is minimized or eliminated.

Click here information on BUG Ratings, Lighting Zones and how BUG Ratings are used. Understanding BUG Ratings

BUG Ratings measure back light, uplight and glare

BUG Ratings measure back light, uplight and glare

Light Trespass

While light trespass in the form of excess light going over a property line does not typically impair the visibility of the night sky, it is an inherent part of dark sky compliance. Light trespass is usually referred to and measured by light going over a property line. As it is considered both trespass and wasteful, communities with dark sky compliance ordinances typically regulate light trespass. Examples of light trespass ordinances are as follows.

  • Light must be less than 1 footcandle (fc) at the property line.
  • Light must be less than 0.5 fc 1 foot over the property line.

The first example limits light as it reaches the property line, thus limiting the amount of light on your own property as the light gets near the property line. The second example limits light over the property line, but the objective could be achieved with proper optics, wattage, mounting height, and a fence to block the light at ground level.

Light trespass by a lake in Massachusetts

Light trespass by a lake in Massachusetts

Kelvin or Nanometers

As noted earlier, most dark sky compliant ordinances will require the Kelvin of the lighting to be lower than 3000 Kelvin, with 2700 Kelvin being more acceptable and 2200 Kelvin being preferred. The warmer the light is, the less impact there is on the night sky and on wildlife habitat. In some instances, the dark sky lighting ordinance will specify a certain nanometer of light such as 590nm or a mix of 590nm and red.

Dark sky 590nm Amber LED wall packs over by a deck over the ocean

Dark sky 590nm Amber LED wall packs over by a deck over the ocean

Other Dark Sky Lighting Ordinaces

There are many other ways that communities decide to regulate lighting. Here are a few.

  • Maximum Footcandles
    • This regulation limits the maximum number of footcandles (FC) that can reach the ground. Northampton MA limits maximum fc to 5fc on most properties.
  • Limit of Light Source Lumens or Light Fixture Lumens per Acre
    • This regulation limits the total quantity of light permitted to be used. For example, Flagstaff limits the total lumens per acre.
  • Max – Min Ratio
    • Max/min ratio is the maximum amount of light in a given area divided by the minimum light in that given area. A typical ratio for commercial or residential egress is 10. Limiting the max/min ratio requires more points of light, less intense light, and delivers more even light.
  • Light Source Visibility
    • Communities may choose to limit light source visibility from another property. While this is a form of light trespass, it is very hard to limit or control. Limiting the visibility of the light source typically requires the light sources to be kept close to the ground.
  • Maximum Mounting Height
    • This is another way to limit light source visibility and keep the skies dark. It limits high mast lighting and depending on how strict the requirements are, may eliminate most if not all pole mounted lighting.

Obviously, there is a lot involved to meet the requirements of dark sky lighting ordinances. Meeting the ordinances requires lighting that can be built to meet the requirements, lighting expertise to know which light fixtures may go where, and computer modeling of how the proposed lighting will comply. Access Fixtures lighting specialists and lighting engineers are ready to help you efficiently and expeditiously meet your local dark sky lighting requirements. Contact an Access Fixtures lighting specialist by calling 800.468.9925 or click here to have a lighting specialist contact you.

A photometric study is a computer-generated model of the light that will be emitted by the proposed light fixtures

A photometric study is a computer-generated model of the light that will be emitted by the proposed light fixtures

Dark Sky Lighting FAQs 

You have dark sky lighting questions. We have answers. If you have a question that isn’t answered below, contact an Access Fixtures lighting specialist at (800) 468-9925 or click here.

What are dark sky lighting guidelines?

Dark sky lighting guidelines aim to minimize light pollution, energy waste, and adverse effects on humans and wildlife. These guidelines encourage the use of properly full cutoff light fixtures with low Kelvin or specific nanometer LEDs to minimize glare, light trespass, and skyglow.

How does dark sky lighting reduce pollution?

Properly shielded light fixtures with low Kelvin or specific nanometer LEDs reduce uplight and light pollution. Shielded fixtures prevent light from being emitted up, thus reducing skyglow.

Which dark sky lights are wildlife friendly?

The answer depends on what type of wildlife is being protected. Dark sky lights are inherently wild-life friendly, but some animals may be better protected by dark sky lights equipped with PC Amber LEDs or 590nm Amber LEDs.  For example, sea turtle hatchlings require 590nm Amber, as sea turtle hatchlings don’t see that spectrum. All wildlife-friendly light fixtures should be full cutoff and use optics that only emit light to where light is required. That will minimize the disruption of natural nocturnal behaviors in animals.

Are there dark sky solar lights?

Yes, dark sky solar lights are available. The difference between dark sky lights and dark sky solar lights is dark sky solar lights are solar-powered.

Can dark sky lights have dusk to dawn features?

Yes. Dark sky lights have all the features of standard commercial lighting fixtures. Many dark sky lights come equipped with photocells that determine when light is required and when the lights should be turned off, ensuring that lights only operate during nighttime hours. Most Access Fixtures dark sky compliant lights can come equipped with programmable microwave sensors that check for light levels and occupancy. The lights only come on when it is dark and someone or an animal is in the vicinity. When no one is in the vicinity, the lights can be programmed to dim or to turn off. This conserves energy, reduces light pollution, and adheres to dark sky guidelines.

What are dark sky lights with 2200 Kelvin LEDs and how is it different from 590nm Amber LEDs?

Dark sky lighting requirements for Kelvin are typically specified at less than 3000 Kelvin. 3000 Kelvin is considered rather higher than what is preferred. 2200 Kelvin, sometimes referred to as “amber white’,  is the preferred choice for dark sky lighting as it is much warmer than 3000 Kelvin. 2200 Kelvin, like 3000 Kelvin is a full spectrum light. While 2200 Kelvin has less blue than 3000 Kelvin, 2200 Kelvin includes the full visible light spectrum. 590nm Amber is a narrow-spectrum light source. It only emits color between approximately 585nm and 595nm. Consequently, like High-Pressure Sodium light, it is only about 20 CRI, and colors basically all appear brownish. 2200K also has a higher lumen per watt output than dark sky light fixtures with 590nm Amber LEDs. For more information click here

Where can I find and purchase dark sky lighting?

Dark sky lighting can be found and purchased at Access Fixtures. Access Fixtures lighting specialists and lighting engineers are ready to help you efficiently and expeditiously meet your local dark sky lighting requirements. Contact an Access Fixtures lighting specialist by calling 800.468.9925 or click here to have a lighting specialist contact you.

How much does dark sky lighting cost?

Typically the initial purchase price of dark sky compliant lighting is around the same price or a little more than basic lighting. The overall cost is usually less if you consider the annual operating cost of the lighting. The majority of lighting expenses are from the operating costs, not the purchase and installation. Check out, What’s a Watt Worth to find out the annual cost of electricity to operate a light fixture. 

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