Dark Sky Illumination Trend Addresses Adverse Effects of Light Pollution

A growing number of cities are passing ordinances to decrease night-time light pollution, and agents in the know are better equipped to help clients.
Photo of a neighborhood and city in the distance at night, as the stars come out in the sky

©MarcelC / Getty Images Plus

For years part of the emphasis on beautifying outdoor yards included some form of landscape illumination. The goal was to up-light trees and shrubs, accent flower beds, pools, paths and houses to showcase them as well as add a sense of safety as dusk turned to darkness.

The technology of low-voltage LED lights offer greater energy efficiency. And as prices came down, home improvement projects that incorporated lighting also became more affordable.

Now, there’s another lighting change underway in urban, suburban and rural areas nationwide. The bright light sent upward into the sky has polluted the air, making it hard to see the sun, moon and stars.

An Overview of Light Pollution

Over the last 25 years, light pollution has increased by at least half and is growing about 10% annually, according to the International Dark-Sky Association (IDA), a Tucson, Ariz.-based organization focused on reversing the issue. One-third of the world’s population can’t see the galaxy at night that makes up the Milky Way, according to Stephen Loring, arctic archaeologist and museum anthropologist with the Arctic Studies Center at the Smithsonian’s National Museum of Natural History in Washington, D.C. The effect of light pollution is part of an exhibit that Loring co-curated titled “Lights Out: Recovering our Night Sky,” which continues through April 2025.

It’s an important exhibit, Loring says, because light pollution adversely affects all forms of life on Earth. Bright light hurts plants, animals, insects, fish and people by affecting their natural rhythms and habits. “Birds pay a heavy price and are sometimes killed when artificial lights throw them off course,” says astronomer John Barentine, who started Tucson-based Dark Sky Consulting to help decrease light pollution. “The lights hurt other animals by exposing them at night to predators. In other cases, certain insects like fireflies can’t find their mates because they can’t see them signaling,” Barentine says.

Excessive night light also causes problems for humans, and not just because they can’t enjoy the wonder of night-time celestial bodies, Barentine says. “Exposure to artificial light at night disrupts circadian rhythms, which, in turn, lessens production of melatonin, the hormone that promotes sleep,” he says.

While light pollution has existed for decades, more buildings and denser neighborhoods have increased the problem, particularly after the Second World War. In 1958, Flagstaff, Ariz., passed the first outdoor lighting ordinance, which outlawed searchlights for advertising to protect the sky overhead. The city’s local Lowell Observatory was concerned that pollution would limit its telescope’s capacity. Tucson adopted an outdoor lighting ordinance on June 5, 1972, so that night lighting wouldn’t interfere with its astronomical observatories, according to an article by Dr. David Portree.   

The Environmental and Monetary Cost of Light Pollution

Since its founding in 1988, IDA has helped guide businesses and homeowners to light their environment with as little bright light as possible. IDA points to several reasons for reducing light pollution at the commercial and personal levels. One is the huge waste that comes from artificial brightness or “skyglow.” About 20 to 50% of the light that shines into the night sky is said to be lost due to fixtures being unshaded, which results in an estimated economic cost of about $3 billion, says Brian Liebel, Director of Strategic Initiatives at IDA. “We all pay that cost, either directly through utility bills or in the prices of goods and services, into which infrastructure costs are rolled.”

In addition, about 15 million tons of C02 is emitted each year to power residential outdoor lighting, which would require that 600 million trees be planted to offset that carbon emission amount. Lighting expert Dawn Brown, Associate IALD, CLD, with Canadian architecture and engineering firm WalterFedy said in a podcast titled Light Pollution is Pollution, “We can see better under natural light conditions rather than bright light.”

The good news is that the problem is solvable, says Loring. “Lights don’t have to be on all the time, can be angled downward and even turned off at times, including when birds migrate and might strike buildings because they’re distracted,” he says.

How Communities are Addressing Light Pollution

Arizona cities may have jumpstarted this country’s effort to decrease light pollution, but other cities, municipalities and states are joining the initiative. Some are adding regulations to zoning ordinances that residents must follow when they install lights outdoors. New Mexico passed its comprehensive Night Sky Protection Act in 1999, one of the first of its kind to make dark skies a focus, says Loring. Eighteen other states, plus Washington, D.C., and Puerto Rico, have some type of state-level law governing outdoor lighting. About 40 cities internationally have also acted. A list that’s regularly updated appears on IDA’s website.

Amanda Padilla, a senior planner with the zoning department in Bee Cave, Texas, a certified IDA International Dark Sky Community, said her city, 20 minutes outside Austin, approved a new light ordinance this past February to protect its surrounding preservation acreage. “We wanted to ensure that surrounding lands and our ecosystem as well as residents’ health and well-being would be protected from the harmful effects of light pollution,” she says. The city doesn’t limit residents to using a set number of light fixtures on their property but wants homeowners to make an intentional effort to pare light pollution, she says.

Builders and Developers Accommodate Solutions

Another step pushing the concept forward is that more builders and developers are following IDA guidelines so that new communities they construct may qualify as a dark-sky community. Such places often appeal to homebuyers who are interested in sustainability or conservation.

The 180-acre Canyon Pines development, planned by Chad Ellington and surrounded by 1,200 acres of open space in Arvada, Colo., which is just outside Denver, reflects such goals. The community includes 90 custom homes and seven to eight miles of trails. In keeping with the philosophy of preserving the natural environment and its wildlife, the right light fixtures and bulbs will be required as construction begins. “We want to preserve the site as well as comply with the city of Arvada, which doesn’t permit up-lighting on trees or houses,” says Ellington. He says complying with requirements is easy and doesn’t incur much in the way of additional expenses. Interested homeowners who buy into the community must submit a light plan for review and approval.

How Real Estate Professionals Can Counsel Clients

To aid the dark-sky illumination initiative, real estate professionals might encourage homeowners outside communities with light-specific guidelines to follow those regulations on their own accord. The IDA lists five key rules on its website and encourages residents to be good neighbors and not “light trespass” or direct light pollution onto a neighbor’s property:

  • All light should have a definite purpose. Before installing any, homeowners should weigh reflective paint or self-luminous markers instead of permanently installing outdoor lighting.
  • Light should be directed only where needed, which is made easier with a shield and by aiming the light beam, so it points downward.
  • Low light levels limit the amount of light.
  • Light should be used only when it is needed rather than left on 24/7; that is why motion detectors and timers are useful.
  • Light colors should be carefully selected and preferably warmer colored rather than blue-violet. “The blue scatters the light more in the night sky and increases the level of light pollution,” Libel says.

But it’s not just night-time outdoor light that should be curtailed, says Liebel. “Most of our time is spent indoors and so it’s important when inside to dim your lights and use warmer color lights at night, about 2700 Kelvin or lower,” he says.

As a real estate pro, you may want to suggest clients purchase outdoor lights that include an IDA label since these products will minimize or reduce glare, light trespass and skyglow and harmful blue light. IDA does not sell lighting but offers an FSA Database with fixtures that have been certified as dark-sky friendly. To help clients find retailers that sell proper lighting, they might visit the Dark Sky Retailers page. Those who follow IDA’s steps [NS1] [BB2] can display its Dark-Sky Friendly Home certification once they submit results to comply.

Nowadays when homeowners hire professionals to install outdoor lights to showcase trees, large shrubs or art, they might ask installers to follow similar guidelines. One expert, Sacramento, Calif.-based landscape designer Michael Glassman, does this and suggests not illuminating an entire plant or artwork but directing light toward interesting branches or part of the artwork and pointing it down rather than up into the sky.  

There’s no federal legislation yet, but Barentine remains hopeful that may happen. “My hope is that as a society we will come to fully appreciate the significance of light pollution as a problem on par with other kinds of pollution Congress has chosen to regulate,” he says.