According to Department of Energy statistics, about 22 percent of all electricity generated in the United States is used for lighting, and about 10 percent of that is used for outdoor lighting and signs. While outdoor lighting is important for illuminating roadways, parking lots, buildings, and monuments, light spillover from this process has more far-reaching effects on the health and welfare of society and the environment than previously understood.

Among other negatives, excessive light pollution is responsible for inhibiting astronomy and the enjoyment of a starry night and the natural world around us, disturbing the circadian rhythms of animals and the ecosystem, creating glare, and impairing human safety and security.

“Additionally, this past summer, studies by the American Medical Association revealed that excessive, unshielded light at night is a health hazard that can increase the risk of cancer and other diseases,” said James Benya, director of the Advanced Lighting Design Program at the California Lighting Technology Center at the University of California, Davis.

Other evidence suggests that light pollution can even affect air quality, according to a study by the National Oceanic and Atmospheric Administration (NOAA) and the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado. According to the study’s findings, uplight from outdoor lighting that contributes to sky glow over cities has been found to impair the natural ability of nitrogen oxide to clean the atmosphere and break down smog, ozone and other irritants during nighttime hours.

Establishment of outdoor lighting standards

Founded in 1988 in response to increasing concerns about the threat that nighttime light pollution poses to society and ecology, The International Dark-Sky Association (IDA) was chartered to promote awareness of these environmental issues and lobby for outdoor lighting standards.

“In addition to decreasing the amount of light pollution emitted, a reduction in unnecessary uplighting from outdated or unshielded fixtures can also save 20–30 percent of the energy consumed by outdoor lighting nationwide and perhaps as much as 50 percent if all outdoor lighting is addressed as proactively as possible,” said Bob Parks, executive director for the IDA, of the comprehensive benefits accrued by the pursuit of informed lighting practices. “Outdoor lighting standards would clearly help to reduce the nation’s energy dollars spent, improve the environment, and enhance our health and well-being.”

In 2005, the IDA took the initiative by joining forces with the Illuminating Engineering Society of North America (IES) to develop new outdoor lighting guidelines. While there still are no national or international standards enacted to control light pollution in most of the world, including the United States and Canada, the IDA has made significant progress toward this end by creating new standards for sound nighttime and outdoor lighting practices.

A model code

Based on the IES’s TM15 evaluation system for outdoor lighting, the joint IDA/IES Task Force developed a model lighting ordinance (MLO), a model code designed to be used by all states, agencies and municipalities in North America for outdoor lighting. According to IDA/IES Task Force member and former co-chairman Benya, the MLO uses five lighting zones (LZ0–LZ4), which describe different types of outdoor areas based on their degree of development and urbanization. “LZ0” describes a natural area such as a national park, while “LZ4,” the other extreme, would include the downtowns and entertainment districts of major cities as well as night activity in heavy industrial and commercial areas, such as rail and shipping yards. Along the spectrum, “LZ1” corresponds to rural areas and suburban residential areas, “LZ2” to suburban commercial areas and urban residential areas, and “LZ3” to most urban commercial areas. Communities are encouraged to incorporate the LZ system into their planning and zoning activities.

Another important part of the MLO is a recently developed outdoor luminaire rating system called “BUG,” which was added to IES’ TM15. An acronym for “backlight uplight glare,” the BUG rating system uses photometric data to “rate” luminaires for their applicability in each of the lighting zones. Three BUG values are given to every outdoor luminaire, such as “Backlight 2, Uplight 3 and Glare 4,” or BUG 234. The highest number determines the lowest lighting zone number in which the luminaire can be used, so in this example the luminaire can only be used in Lighting Zone 4 (LZ4). If a luminaire receives a BUG value of 5, the luminaire doesn’t meet the BUG limits for any lighting zone.

“In general and with rare exception,” Benya said, “all outdoor lighting, regardless of its technology and the zone it’s classified for would now need to be fully shielded so that no light goes above the horizontal plane. In addition, the lower the lighting zone, the lower the lumen package or wattage. For instance, it’s unlikely that a luminaire over 20–30 watts [W] will ever achieve BUG 000, but luminaires as powerful as 400W or more might make it within BUG 444.”

Products in practice

“Standard floodlights, conventional wallpacks, and old globe and acorn-style outdoor fixtures are ‘glare bombs’ and won’t meet any of the standards any longer except under very rare circumstances,” Benya said.

What will meet the standards?

“We encourage electrical contractors to shift to luminaires incorporating LED, ceramic metal halide, high-pressure sodium, compact fluorescent and induction lighting technology,” he said. “I’m recommending LEDs more and more every day because, as point sources, they direct light very effectively and can also be put on programmable timers to enable even further control, which is a powerfully important concept when it comes to minimizing light pollution at night.”

Jim Eddy, division manager at Taft Electric in Ventura, Calif., agrees with Benya in the importance of good and environmentally responsible lighting products and practices.

“End-users don’t always think about the environmental fallout of their lighting decisions, but it’s our job as electrical contractors to make them aware of how their light can spill over onto other properties,” he said. “In addition, many of the older, standard fixtures end up in landfills when they reach end-of-life, so it’s important for customers to understand how these products impact the environment.”

Eddy cites standard HID fixtures used in parking lots and on building exteriors as some of the biggest culprits behind today’s light trespass problems and favors induction technology for its long life, high quality light distribution and ability to minimize light bleed thanks to the market availability of a variety of well-designed, shielded fixtures.

According to Benya, communities have been adopting the new standards on a case-by-case basis.

“Some communities don’t care about light pollution at all and some do, and some people don’t like change,” Benya conceded. “But the standards are very robust, and we’ve been witnessing their increasing adoption by more and more towns nationwide. The beneficial aspect of codes is that they help standardize products so that they can be built to specs as well as standardizing practices, which then allows for the development of training programs for contractors so that they can meet the code.”

Next steps

While the code’s various lighting zones allow it to be fitted to any community, Benya said the IDA’s current work on a “short” version of the code will hopefully simplify it for smaller communities and help increase its adoption.

“The next leading edge of activity is on developing restrictions on the color of light,” he said. “For example, light on the bluish edge of the spectrum has more impact on living beings; there’s been an increasing movement in the industry towards the use of warmer-tone outdoor lighting, preferably 3,000K or less. For instance, 2,200K LED technology has just been announced.”

“Overall,” Benya said, “Dark-Sky is helping to promote greater awareness of environmentally sensitive lighting. This world is where we live and eat and where our kids play—why would we want to be polluting it? The fact is, with a little education, we can do something positive using great new lighting technology that’s already available.”