The October release of the IDA Model Lighting Ordinance 2005.3 promises to further a movement that has already made great strides.

A few years ago, discussion about the dark sky movement focused on defining terms and explaining the issues. Today, owing to the efforts of lighting professionals, astronomers, and active citizens, dark sky concerns are becoming part of the public consciousness and a healthy contender with sustainability for the attentions of policymakers. In addition to a growing commitment from municipalities, and even utility companies, a revision of the 2004 IDA Model Lighting Ordinance (MLO), due to be released this October, should lead to increased implementation of dark sky-friendly action plans in towns and cities across the country. While such ordinances have not been widely adopted to date, the International Dark-Sky Association (IDA), the organization that authored the MLO, expects that eventually such regulations will become a national standard. For designers with outdoor lighting projects on the boards that may be affected by dark sky mandates, keeping an eye on local codes is an advisable practice.

Light pollution, a symptom of poorly designed, inefficient outdoor lighting, has costly effects, such as impaired views of the night sky, hampered visibility, and a negative effect on ecosystems. (Light pollution can disrupt the path of migratory birds, for example.) As many in the dark sky movement have attempted to prove, loss of the nighttime skies does not have to be the inevitable price of progress or urban growth. Through education, thoughtful planning, and policy change, many portions of the country have seen a reduction in light pollution, despite population increases. Tucson and Flagstaff, Arizona; Palm Springs and the Palm Desert area in California; and Jackson, Wyoming, for example, have all documented decreased light pollution, owing largely to the adoption of solid ordinances in each community. Light pollution can be measured by analyzing and quantifying sky glow over cities and regions of the world based on methods developed by the Italy-based Light Pollution Science and Technology Institute. These calculations are generated from measurements of upward light flux, obtained via images from the Defense Meteorological Satellite Program of the United States Air Force.

The international lighting industry, in particular, has rallied to address the issue of light pollution. Associations including the Illuminating Engineering Society of North America (IESNA) and the Vienna-based International Commission on Illumination (CIE) have created technical committees to study sustainable lighting and light pollution, and to develop guidelines and recommended practices. This commitment can be seen in documents such as IESNA RP 33-99, which provides standards for external environmental lighting and specifically addresses light pollution; or CIE publications 01:1980 and 150:2003, which provide guidelines for minimizing sky glow near observatories and limiting obtrusive lighting in outdoor installations, respectively.

In some circles, the dark sky agenda is considered as relevant as other environmental threats, such as inefficient energy use. The U.S. Green Building Council, for example, has included one point for light pollution control in its LEED rating system, a set of voluntary standards for developing sustainable architecture. The point is awarded to designs that meet IESNA recommended illuminance values, do not cause glare, and prevent light from being directed into nearby roadways, properties, or the sky. Efficient lighting and light pollution concerns are also part of the Energy Star Program sponsored by the U.S. Environmental Protection Agency and the U.S. Department of Energy. A voluntary labeling program, Energy Star was designed to help home- and business-owners identify and use energy-efficient products and strategies. The current version of the program's commercial building manual devotes a chapter to energy-efficient lighting techniques, and builds dark sky concerns into its recommended practices, including recommendations for lighting ordinances and usage zones.

While utility companies are not often considered environmental allies, several power providers, such as the Long Island Power Authority (LIPA) and Connecticut Light and Power (CL&P), are looking to change the industry's reputation. CL&P became a lifetime IDA member in 2002, and has made dark sky-friendly luminaires and lighting recommendations available to its customers. LIPA, which provides electric service to 1.1 million customers, implemented a program in 2003 to phase out the high-wattage, unshielded luminaires currently in use by its commercial, industrial, and municipal customers in favor of shielded, low-wattage fixtures. LIPA no longer offers 1,000W lamps as part of its commercial lighting program and has instead added 50W, 70W, and 100W options. In addition, information about light pollution and dark sky-compliant lighting is being added to its website and customer inserts. LIPA's awareness is the result of the concerted efforts of SELENE, a grassroots organization of New York State residents that advocates sensible, efficient, and dark sky-friendly lighting.

The release of the Model Lighting Ordinance this month represents an important step for the IDA, which has worked against light pollution and other threats to the nighttime environment since its incorporation in 1988. IDA is a nonprofit organization with more than 11,000 members in a variety of disciplines (from design to astronomy) located in the United States, as well as in 75 countries worldwide. The IDA works alongside organizations such as New York's SELENE and the Britain's Campaign for Dark Skies. Most amateur astronomy groups also have light-abatement committees that focus on dark sky issues. The community's progress can be measured partially in the number of municipalities that have adopted lighting ordinances. The first was Tucson, Arizona, in 1972. Over the last 30 years, more than 1,000 ordinances have been established across the United States, the majority going into effect in the last five years. With the release of the MLO, the IDA hopes to keep this momentum.

The MLO began with a working group, organized by the IDA and chaired by James Benya, in 2002. The group gathered together a range of professionals, including astronomers, lighting manufacturers, technical lighting organizations, lighting designers, and city planners. After a year, it was dissolved, and the IDA completed the remaining work on the MLO, introducing the first version in June 2004. It is not intended as an educational document, but a technically sound, legally enforceable code that dark sky-aware municipalities can easily adopt as their own ordinance without research and legal fees. In this sense, the MLO is not like IESNA's RP 33-99, which is a set of 'recommended practices'; nevertheless, many of the ordinance's standards are influenced by documents such as RP 33-99, CIE-150, and other present ordinances and codes in practice across the country. (The following states have already adopted legislation: Arizona, California, Colorado, Connecticut, Georgia, Maine, New Jersey, New Mexico, Texas, Rhode Island, and Wyoming. Ten more have introduced legislation.)

The MLO combines three main ingredients: lighting zones (location and usage should determine appropriate levels of ambient light), shielding requirements (all fixtures should be well shielded), and control over the amount of light used. Five standard lighting zones have been defined, whose designations are based on population, commercial use, and acceptable levels of ambient light. (See 'Maximum Luminaire Wattage,' above.) For example, much higher light levels are acceptable in New York's Times Square than would be appropriate for Yellowstone National Park. Per zone, the ordinances restrict the type of lighting, and its location, the amount permitted, fixture-shielding restrictions, and lighting curfews.

The first draft of the MLO was released in 2004 and underwent an intense public review period, during which more than 30 commentators from various fields critiqued the document-producing thousands of pages of comments. Reviewer recommendations included making the document more 'user-friendly' and 'accessible.' Changes were also made to reflect revised methods of light control: Prior drafts used maximum power densities (watts per square foot) to control ambient light. Future drafts will also include recommended lumen densities (lumens per square foot) to compensate for the different efficacies of various light sources. The revised version, 2005.3, will be available late in October 2005, after which it will continue to be updated periodically to reflect current research and new technologies.

In January 2005, IDA also established the Fixture Seal of Approval, a program that will address the demand for third-party certification of dark sky-friendly luminaires. Manufacturers may submit their fixtures' photometry data to the IDA for analysis of the light output distribution, and upon meeting qualifications, receive the IDA Seal of Approval for use in sales, marketing, technical, and packaging materials. Currently, 16 manufacturers have IDA-approved fixtures, though many others who have not applied for the seal of approval do offer full-cutoff fixtures. (A comprehensive list of both is available on the IDA website at This program should help simplify the specification process for concerned consumers, builders, and facility managers, and assist in establishing standards for designation.

The market for sustainable lighting is promising, and the concerted efforts of professionals and laypersons alike are helping communities control light pollution. Given their understanding of both the technical and design issues, lighting professionals are in a unique position to influence this issue, by participating in sustainable lighting technical committees or guiding clients toward energy-efficient, dark sky-friendly luminaires and lighting plans. It should be an easy sell, as dark sky-sensitive lighting principles are generally applicable to energy-efficiency scenarios: Shine light only where needed; use only the amount required to see well; and turn lights off when not in use. Such designs will result in energy, and thus financial, savings; improved visibility; and a slice of the night sky. Perhaps those who enjoy a view of the stars will make some wishes on behalf of the rest of us. susan mcgowan

Susan McGowan is a freelance writer based in Columbus, Ohio. She recently joined the staff of the International Dark-Sky Association.