Light pollution – excessive lighting that escapes into the sky – touches our lives every day. Unlike water or air pollution, light pollutes its surroundings by decreasing visibility. Much like implementing a recycling program, addressing light pollution is simple, cost effective, and benefits your bottom line.
How Low Can You Go?
Targeting light pollution will generate immediate and ongoing savings – concrete percentages that contribute to your bottom line. Bradford Leach, a lighting management consultant for GonLED, finds that the real cost savings lie in making incremental changes around your facility.
For example, for every 3kW of lighting energy saved with LEDs, your AC load is reduced by 1kW. T8 LED tubes are an ideal replacement for T8 fluorescents because they generate the same amount of light yet operate at a lower wattage. Depending on its use, you may get the same coverage of a 150-watt bulb as you can with a 10-watt bulb. Window film typically decreases energy use by up to 10%. Through the Energy Policy Act of 2005 (EPACT), tax deductions for reducing energy consumption is 60 cents a square foot.
"Addressing light pollution saves money, and makes lighting more comfortable and functional," says Terry McGowan, a National Lighting Bureau associate and lighting consultant for Lighting Ideas Inc. "Just have lighting obey the laws of good lighting design and everybody's going to be happy. And that's hard to argue with."
The Environmental Consequences
Often presented as an issue of stargazing, light pollution may appear to be a nostalgic concern of amateur astronomers. While it's true the majority of Americans cannot view the Milky Way, light pollution is far more complex than missing out on shooting stars. Johanna Duffek, outreach and education manager for the International Dark-Sky Association (IDA) emphasizes, "light pollution impacts the astronomy industry, is not safe lighting, adversely affects wildlife and human health, and is a waste of energy."
In animals, excessive lighting interferes with their ability to distinguish between night and day, altering their nocturnal habits. Predator-prey relationships can also be compromised, leaving certain animals more exposed at night. Birds' migratory patterns can be lost altogether as they cannot depend on the moon and stars for navigation. Even reproductive cycles can be stunted, threatening the survival of an entire species. For example, turtles hatching on beaches will crawl toward artificial light and human activity.
For humans, glare is the predominant issue. Particularly at night, over-illumination and poorly directed light can distract drivers or cause harsh shadows that pose a security threat. Studies have also shown that glare from interior fluorescent lights can cause eye fatigue, migraines, and stress, which lead to decreased productivity.
Types and Causes
Light pollution is a result of inappropriate, and sometimes unwarranted, levels of light. The most common types are:
- Light trespass – unwanted light escaping to adjacent properties
- Over-illumination – excess use of light
- Light clutter – clustered groupings of light
- Skyglow – as seen over large cities
Each of these forms can also be a result of poorly configured light sources, improper fixtures or bulbs, incorrect wattage, incomplete maintenance, or out-dated technology.
Commercial facilities contribute to light pollution at greater rates than homeowners due to their footprint and height. "One way commercial facilities contribute to light pollution is light from the building's interior escaping out into the night," says McGowan. "The second way is from outdoor lighting, whether it be from the parking lots or decorative flood lighting. As far as the building owner is concerned, both represent wasted energy."
No Fuss Evaluations and Solutions
Addressing light pollution doesn't need to be a headache. In fact, all it requires is the presence of mind to evaluate the type of lighting you already have. Use the same mentality that dictates football field lights should be turned off when not in use – just on a smaller scale.
Duffek recommends conducting a simple walkthrough of your facility at night and asking these questions for each light source:
- What is this light's function? Is it doing its job?
- Is the level of lighting appropriate, or can it be reduced?
- When is this lighting in use and for what purpose?
- Is good color rendition or facial recognition needed from the wattage type?
These questions allow you to identify lights that need further evaluation. You can even do a drive-by at night to see if internal lights are being left on.
More often than not, simple solutions exist in LEDs, low pressure sodium bulbs, reflectors, shields, dimmers, sensors, timers, and window film that can be installed with relative ease. You can also put in blinds and window coverings, instruct cleaning crews to turn off after-hour lighting, and experiment with replacing bulbs with a lesser wattage.
For a comprehensive evaluation of your facility, you can get a lighting energy audit from electric utilities, energy contactors, or lighting designers. "I have yet to see any commercial installation where I could go in and not save the owner more than what I would charge to do an audit," says McGowan. Professionals will take readings on foot-candles to establish the baseline, provide recommendations, calculate payback periods, and provide information on tax incentives, explains Leach.
Taking the Edge Off
Parking lot and garage lighting is an obvious culprit to assess. Many parking lots feature cobra head or partial cut-off fixtures. "These unshielded lights are often too powerful for the job and light escapes up in an uncontrolled way," says McGowan. Approximately 30% of the light "leaks" into the sky – meaning only 70% is directed toward the ground where it's needed.
You should also question how much of your outdoor lighting is truly essential. If you have a traditional 9-to-5 business, there's no reason to keep an empty parking lot or garage blazing every night of the week. You may find just half of the lights will be bright enough to address safety concerns. Dimming the lights to a lower percentage on certain nights may also be an easy solution. "Lighting that is inappropriate because of color, brightness, or quality isn't doing the job it's intended to do – more isn't necessarily better," advises McGowan.
Dark-sky friendly fixtures, for example, provide full cut-off shields and flush bulbs to eliminate light above the 90-degree angle. Because of their ability to direct light more efficiently, you won't need to increase the number of your poles to get the same coverage, says Duffek. Most manufacturers offer several options that have the IDA-certified Fixture Seal of Approval.
The Chicago Model
For almost a decade, Chicago has been home to the Lights Out program – a voluntary measure to help over 5 million migrating birds that fly over the Windy City each year. The program encourages buildings over 40 stories to scale back their decorative lighting from August to November. Facilities reduce their lights from 11 p.m. until daylight. Those that are entertainment venues, situated on the lakefront, or have extensive glass exteriors should diminish light levels after 1 a.m.
Inspired by Earth Hour and the Lights Out program, BOMA/Chicago has taken these beneficial efforts and crafted them into the Exterior Decorative Lighting Guidelines. "We call attention to the Lights Out program during the migratory bird season, but for the other goals – energy efficiency, light pollution, and reducing your carbon footprint – these voluntary standards are present year-round," says Ron Tabaczynski, government affairs director for BOMA/Chicago.
BOMA/Chicago's guidelines address crown and facade lighting, street-level fixtures, signage, and tree lighting. Evening guidelines call for decorative lights to go on 30 minutes after sunset and off 30 minutes before sunrise. Evening lights should be powered off by 10 p.m. during the week and 11 p.m. on the weekend. These simple, set times make it easy for controls to be programed, so the measures aren't a daily inconvenience. Over 20 buildings have adopted the voluntary recommendations, including Merchandise Mart, Willis Tower, Congress Center, and the Wrigley Building.
Willis Tower has followed all of the guidelines for their decorative antenna and exterior lighting. While precise energy savings are unknown, U.S. Equities found the adjustment to be a strong, public statement about its conservation efforts.
"U.S. Equities operates Willis Tower in-line with sustainable building management practices. Yet many of these initiatives, particularly energy efficiency measures, are not highly visible to tenants of the building," explains Sundee Wislow, director of sustainability for U.S. Equities. "Adjusting our decorative lighting provided an easy and visible way to demonstrate our commitment to addressing light pollution and energy savings with no negative impact to our operations or our tenants' satisfaction."
Jennie Morton (firstname.lastname@example.org) is assistant editor of BUILDINGS.