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A lighting ordinance can ensure safe, aesthetically pleasing, and energy-efficient outdoor lighting that preserves views of the night sky and minimizes harm to species disturbed by artificial lighting.
Uncontrolled outdoor lighting causes a variety of problems, including:
Bright light from unshielded and misaimed light sources can hamper vision, leading to car crashes and other accidents.
Many people find excessive night lighting to be a nuisance. Light that crosses property lines can cause anything from mild inconvenience to bitter disputes between neighbors.
Artificial light, by mimicking sunlight during naturally dark hours, can disrupt the behavior of wildlife and plants. For example, a 2017 study found that artificial lighting reduced nocturnal pollinator activity, which is essential for healthy ecosystems, by 62%.
Lighting fixtures that use inefficient technology, are poorly targeted, or operate at unnecessary times waste energy. The International Dark-Sky Association estimates that 15 million tons of carbon dioxide are emitted in the United States each year to power residential outdoor lighting, and that at least 30% of this light is wasted by unshielded or poorly aimed fixtures.
Uncontrolled night lighting diminishes and obscures views of the natural night sky. At the turn of the 20th century, most people could see a starry night sky from where they lived. A century later, 80% of the world’s population (including 99% in Europe and the United States) lives under skyglow—the diffuse light seen over population centers—according to a 2016 atlas of night sky brightness.
Municipalities can use lighting ordinances to ensure safe, aesthetically pleasing, and energy-efficient lighting that preserves views of the night sky and minimizes harm to species disturbed by artificial lighting. Ordinances can accomplish this by mandating or encouraging the use of shielded light fixtures, intelligent timing controls, improved technology (such as LED lighting), and other methods. Without a strong lighting ordinance and the ability (and willingness) to enforce it, a municipality cannot control and correct outdoor lighting problems.
Lighting ordinances do not necessarily hinder development; rather, they enhance development by preventing poor lighting practices.
The Pennsylvania Outdoor Lighting Council (POLC) is the authority on lighting issues in Pennsylvania. POLC offers a comprehensive collection of lighting-related resources, including:
A guide for municipal officials, planners, code officers, and citizens to advocate for, create, adopt, and enforce an effective lightning ordinance in Pennsylvania. It outlines the necessary steps in the ordinance development process and includes detailed information about specific codes, provisions, and more.
Three model lighting ordinances (zoning, subdivision and land development, and a stand-alone ordinance). POLC updates the models regularly to reflect advances in methodology and lighting technology.
For more information, see the POLC website at http://www.polcouncil.org/
The International Dark Sky Association (IDA) is a recognized international authority on lighting issues, specifically light pollution. It offers a somewhat shorter guide to enacting a lighting ordinance, as well its own model ordinance.
For more information, see the IDA website at http://www.darksky.org/
Dozens of municipalities across Pennsylvania have adopted lighting ordinances. Below are links to ordinances for several of these municipalities. The ordinances are also listed as “Featured Library Items” in the online edition of this guide.
The website eCode 360 contains hundreds of local government ordinances from across the country. If a municipality has posted ordinances there, any lighting ordinance is likely to be included.
 Knop, Zoller, Ryser, et al. “Artificial Light as a New Threat to Pollination,” Nature 548 (2017).
 Falchi, Cinzano, Duriscoe, et al. “World Atlas of Artificial Night Sky Brightness,” Science Advances 2.6 (2016).
Stan Stubbe of POLC wrote the first edition (2009) and reviewed the second edition (2017). Nate Lotze revised and updated content for the second edition. Wes Bruckno of the Chester County Planning Commission reviewed the second edition.
The Pennsylvania Land Trust Association published this guide with support from the William Penn Foundation and the Community Conservation Partnerships Program, Environmental Stewardship Fund, under the administration of the Pennsylvania Department of Conservation and Natural Resources, Bureau of Recreation and Conservation.
© 2017, 2009 Pennsylvania Land Trust Association
Text may be excerpted and reproduced with acknowledgement of ConservationTools.org and the Pennsylvania Land Trust Association.