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
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
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
New bulbs burned longer and brighter, while many fixture designs became
less discreet. Where it once was dark, there was light. And that was
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
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.
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
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
So, what are the solutions?
Many of these problems associated with outdoor lighting can be solved by
using a little common sense.
- The physiology of the human eye must be taken into account when designing
outdoor lighting. To best facilitate peripheral vision at night, "contrast"
between light sources, lit areas and dark surroundings must be reduced.
Softer, more transitional light levels, which are as consistent as possible
from area to area, should be employed. (Recommended levels set by the
IESNA should not be exceeded).6 Also, fully-shielded/recessed light
sources or "full cutoff" type (FCO) fixtures should be the prevailing
choice in all outside installations. Such fixtures and light sources
available from most manufacturers.
- There is no excuse for glare, and it should be avoided in all
applications. This is easily achieved by specifying
fully-shielded/recessed light sources or FCO type fixtures. Any fixture
that presents a viewable light source as part of its functional appearance
is going to affect visual perception at night by varying degrees.
Epitomizing the problem of outdoor glare is floodlighting. No matter how
it is aimed, floodlighting always produces glare, even from extremely
off-axis angles. The wide broadcast of light produced by floodlighting
regularly affects neighboring areas, roadways and the night sky - even
across large distances. Given its lack of redeeming qualities,
floodlighting should ultimately become obsolete.
- Unnecessary and hazardous overlighting, as in commercial "lumen wars" can
be avoided by responsibly following guidelines for the maintained
illumination levels and uniformity ratios recommended by the IESNA.6
Again, glare from these sites is avoided by specifying
fully-shielded/recessed light sources or FCO type fixtures.
- Simply put, efficient use of energy in lighting is that which: (1)
applies all or most of its generated light to the task at hand. (2) Uses no
more light or energy than is necessary for safety in the task area.
- In the security industry today, professionals will attest that if
lighting is used to prevent theft, motion or infrared-sensored lighting
would be more successful than static floodlighting. Since motion or
infrared-sensored lighting creates an alerting "change of environment", it
draws attention to any activity at a site.
- We must increase awareness. The way to achieve better outdoor lighting
is through education. To ignore these many problems and continue pandering
to society's "perception" of good lighting is irresponsible.
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.
- "Outdoor Parking Lot Lighting" Nancy Clanton and James Benya. An E
Source Report. E Source, Inc. 1033 Walnut St. Boulder CO 80302-5114,
- "Light, Sight and Photobiology" Peter Boyce from Lighting Futures
publication/Lighting Research Center, Rennselaer Polytechnic Institute.
- "Night Blindness" by Prof. Arthur R. Upgren, Amicus Journal, Winter 1996,
- "Does Light Have a Dark Side" Janet Raloff, Science News Magazine,
October 17, 1998 Science News, 1719 N St. N.W., Washington, DC 20036
- "Preventing Crime, What Works, What Doesn't, What's Promising" A report
to the United States Congress / The National Institute of Justice
- "Study of Streetlighting and Crime" 7/77 by James M. Tien / US Dept. of
- Lighting Handbook, Illuminating Engineering Society of North America.
120 Wall St., Floor 17, NY NY 100005-4001 / 212-248-5000,
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