Night, Light & Sight

The Overdue Renaissance of Outdoor Lighting

By Bob Crelin

As we stand on the brink of a new century, we find that popular outdoor lighting applications have become inefficient and counter-productive, often working against the laws of human vision and common sense. Glare and light pollution rule the night, and indiscriminate light usage is becoming more of a challenge to the human experience than a benefit.

The goal of this essay is to take another look at conventional exterior lighting. The long overdue "Renaissance" of outdoor lighting will bring about new approaches to lighting design and application; approaches designed to better aid vision, promote efficiency and help us coexist with the natural night environment.

What is the problem?

Outdoor lighting is researched by many and understood by few, yet it is freely employed by all. Conventional outdoor lighting wisdom appears to amount to little more than, "Got a dark area? - put a light up - the brighter, the better". Although research has established a greater understanding of outdoor lighting, the cavernous gap between those who research and those who install couldn't be wider. A lack of awareness has allowed poor lighting to proliferate. As a result, visual perception, safety and quality of life are increasingly compromised.

How did we get to where we are today?

Since the discovery of fire, we have embraced the presence of light during the night. As electric lighting became widespread, film and television helped to mold the public's fear of night, using darkness as a backdrop to terror. As automobiles became commonplace, the streetlight market exploded. New bulbs burned longer and brighter, while many fixture designs became less discreet. Where it once was dark, there was light. And that was considered progress.

Addicted to light and conditioned to glare.

In outdoor lighting applications today, function lags behind flamboyance and fear. Once installers began flooding outdoor areas with illumination, the results - glare, light trespass and light pollution - became grudgingly accepted side-effects of modern life. Because most people are now accustomed to glare and excessive brightness during the night, appropriate night lighting might appear inadequate. By pandering to this misconception, outdoor lighting has become commonly measured by sheer quantity, not quality.

Back to square one.

In popular outdoor lighting we commonly overlook some basic, unchangeable facts about ourselves and the world around us. The science of lighting application has become increasingly complicated. In order to grasp the basics, then, it is necessary to take a few steps back and ask: Is the application of outdoor lighting optimized for vision and safety at night? Should we be concerned that indiscriminate lighting is gradually eliminating the natural night environment?

Battling Mother Nature.

The human eye was not designed to contend with artificial light at night. While the eye is a extremely complex organ, its ability to address different levels of visible light is fairly basic. Over millions of years, the eye's ability to adapt from the uniform light of day to the darkness of night has evolved. Because of this design, the eye can only adjust to one light level at a time - which is determined by the brightest level - so it cannot see in bright and dark areas concurrently. That is why we have difficulty seeing peripherally when we experience contrasting brightness against a nighttime scene. Our peripheral vision is critical for safe navigation, so to compromise peripheral vision is to compromise safety.

Glare

Glare goes a step beyond extreme contrast by diminishing vision within the eye itself. Most of us know the sudden blindness, disorientation and pain of extreme glare caused by a flashlight aimed into our faces at night, or the dazzle of oncoming headlights when we drive. Varying degrees of direct glare are common place in outdoor lighting today. Modern light sources are at an all-time high in lumen output, and thanks to many common fixture designs, our eyes are often forced to directly experience the full-on wrath of their disabling power. When strong glare is present in one's line of sight, a "veiling" effect degrades the eye's ability to discern anything but the brightest objects in its field of view, further compromising vision and safety.

Adaption

Everyone recognizes that time is needed for the eye to adjust to dark areas after exposure to bright light. This process can take anywhere from several seconds to several minutes. In the competitive world of fast food restaurants, gas/service stations and car dealerships, marketing trends have dragged outdoor lighting into the marketplace battlefield, and "lumen wars" have erupted across the country. When a patron visits one of these establishments, the levels of extreme illumination force his or her eye into more of a daytime range. After pumping gas, chomping burgers or car shopping, the patron gets behind the wheel of his or her vehicle and reenters the night world, not yet fully adjusted to the darker roadway. The hazard is clear. The driver will literally be driving blind for some seconds.1 Although headlights and streetlights may offer some perceptible illumination, the driver's vision is compromised until adequate adaption has taken place.

Tick, tock - internal clock.

Physiologically speaking, life forms on Earth are not meant to experience artificial light at night. One of the most unexplored aspects of artificial light is its long-term effect on the Earth's creatures. Throughout evolution, our planet's regular cycles of natural light have become integral to biological rhythms. In humans, exposure to light affects many physiological variables, such as the daily patterns of core body temperature, levels of melatonin, urine production, cortex activity and alertness.2 In plants and animals today, we can witness short-term confusion of daily and seasonal patterns caused by artificial light. For example, in climates that experience winter, trees and plants near outdoor lighting display noticeable retardation during foliage change, and sometimes, a delayed loss of leaves. Birds can sometimes be seen encircling bright uplighting, or heard serenading the false dawn in the middle of the night.3

A Science News magazine cover story, "Does Light Have a Dark Side?", details research suggesting a possible link between chronic artificial light exposure at night and elevated cancer risk.4 Although this research is still in its beginning stages, evidence suggests that the exposure to illumination at night can disrupt normal physiological operations in humans as well.

Efficient energy use.

There are few electrically powered devices today that waste as much of their generated product as many common outdoor lighting fixtures do. The night sky over most communities is aglow with wasted illumination from misdirected or overdone lighting. More often than not, lighting is generously applied to an area or subject, with little attention paid to containing light within the task area. The resulting light intrusion into areas outside the task area have created modern-day afflictions called Light Pollution and Light Trespass.

Security lighting... or Insecurity lighting?

Lighting is often installed to deter or prevent crime. For site security, "maximum coverage" fixtures are typically used like dusk-to-dawn floodlights and unshielded wallpacks. The glare from such lighting causes extreme contrast and promotes low peripheral visibility, thereby defeating its purpose. Although static dusk-to-dawn lighting "feels" like a protective measure, it can actually assist criminals more than deter them. Major studies on security lighting's effect on deterring crime are at best inconclusive.5

So, what are the solutions?

Many of these problems associated with outdoor lighting can be solved by using a little common sense.

In Summary.

At this juncture, we must look at where we are and learn from our mistakes. Our goal for the future must be to balance the functional needs of lighting with the unchangeable givens of nature's design. Five-hundred years ago, a Renaissance challenged convention and illuminated the world. In the next millennium, our challenge is to illuminate it wisely.

Footnotes

  1. "Outdoor Parking Lot Lighting" Nancy Clanton and James Benya. An E Source Report. E Source, Inc. 1033 Walnut St. Boulder CO 80302-5114, www.esource.com
  2. "Light, Sight and Photobiology" Peter Boyce from Lighting Futures publication/Lighting Research Center, Rennselaer Polytechnic Institute. http://www.lrc.rpi.edu/Futures/LF-Photobiology/Index.html
  3. "Night Blindness" by Prof. Arthur R. Upgren, Amicus Journal, Winter 1996, http://www.nrdc.org/eamicus/clip01/aulight.html
  4. "Does Light Have a Dark Side" Janet Raloff, Science News Magazine, October 17, 1998 Science News, 1719 N St. N.W., Washington, DC 20036 http://www.sciserv.org
  5. "Preventing Crime, What Works, What Doesn't, What's Promising" A report to the United States Congress / The National Institute of Justice http://www.ncjrs.org/works/wholedoc.htm
  6. "Study of Streetlighting and Crime" 7/77 by James M. Tien / US Dept. of Justice, http://www.darksky.org/ida/ida_2/info63.html
  7. Lighting Handbook, Illuminating Engineering Society of North America. 120 Wall St., Floor 17, NY NY 100005-4001 / 212-248-5000, http://www.iesna.org

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