presentation, August, 2008 Click to begin.

PERPETUAL TWILIGHT: Our Careless Destruction of the Night, And How To Reverse It

PERPETUAL TWILIGHT: Our Careless Destruction of the Night, And How To Reverse It Presented by the Illinois Coalition for Responsible Outdoor Lighting ©

More than 80% of Americans live in urban areas. Urban areas which tend to be dominated by manmade light.

Since earliest times, humans have tried to create light, to drive back the frightening dark.

But modern technology has allowed us to take the light of a few campfires, and multiply it billions of times over.

Our primitive fears of the dark, and our headstrong drive to extend our daytime activities, has led us to the point where our nighttime is flooded with light.

Star-filled skies, which inspired countless generations

Star-filled skies, which inspired countless generations have faded to pale, endless twilight.

Star-filled skies, which inspired countless generations have faded to pale, endless twilight. Will our children, or theirs, ever witness the magnificence of the universe above them?

A daily cycle of light and dark has provided a pulse to living organisms on Earth since life appeared eons ago.

Our human bodies retain important internal functions regulated by the day/night cycle, too.

But manmade light at night can disturb natural cycles, harming both our world and ourselves.

Equally disturbing is the amount of energy we consume to light our world,

Equally disturbing is the amount of energy we consume to light our world, and the percentage of that energy which is wasted. Manmade light shining from North America, imaged from high Earth orbit.

Equally disturbing is the amount of energy we consume to light our world, and the percentage of that energy which is wasted. Relative nighttime sky brightness over North America.

If we intend to light up areas on the ground, so we can be active at night, why is so much light shining up into our skies? Relative nighttime sky brightness over North America.

The electricity consumed to light the skies over our nation to this level equals the total output of dozens of generating plants running at full power. Relative nighttime sky brightness over North America.

Add in the light which shines in other directions, outside of the areas we intend to illuminate, and the energy waste from poor lighting is staggering. Relative nighttime sky brightness over North America.

And the waste goes on, hour after hour after hour, Relative nighttime sky brightness over North America. night,after night,after night…

Where does the waste come from?

From operating lights when theyre not needed From over-illuminating And the most common source, From poorly engineered lighting fixtures

Where does the waste come from? From operating lights when theyre not needed (Example: Lights left on all night) From over-illuminating (Example: City park with overly- redundant light placement) And the most common source, From poorly engineered lighting fixtures (Example: Mall lot lights sending as much of their output in sideways glare as in downwards illumination)

How can we remedy the situation?

Answer: Use light fixtures which put the light only where it is needed. Many common fixtures send their light output to places other than where theyre meant to illuminate.

Answer: Use light fixtures which put the light only where it is needed. Many common fixtures send their light output to places other than where theyre meant to illuminate. This directly wastes a large percentage of the energy, and can create hazardous, unsightly glare.

Answer: Use light fixtures which put the light only where it is needed. Wasteful torch fixturesDownward focused fixtures

Answer: Use light fixtures which put the light only where it is needed. Hanging fixturesRecessed fixtures

Answer: Use light fixtures which put the light only where it is needed. Globe-top fixturesDownward focused fixtures

Answer: Use light fixtures which put the light only where it is needed. If all of a fixtures light output is focused on the area to be illuminated, a lower wattage lamp can be used than is needed in a wasteful fixture. Energy use can be cut tremendously, and much harmful stray light eliminated. 63% ENERGY WASTE FROM ACORN-TOP FIXTURES

Answer: Use light fixtures which put the light only where it is needed. But we can see the direct glare from this light, and others all the way down the street, because they wastefully send their output where it isnt needed. The green lines indicate the zone which this street lamp is intended to illuminate.

Answer: Illuminate only to the levels needed. When it comes to nighttime lighting, more isnt necessarily better. It can just mean more power consumption, and more glare. Chicagoland at night from Earth orbit. Years after the City of Chicago completed its massive installation of thousands of new street and alley lights to combat crime, the Citys own studies found no resulting decrease in street crime.

Answer: Operate lighting only when needed. Much outdoor lighting serves the needs of activities which do not take place over the entire night. By shutting of lighting during non-use hours, or reducing it to safety/security levels, tremendous energy savings can be achieved. Auto dealer with all lot lights on after closingAuto dealer with lights down to security level after closing

The future is up to us to shape.

Lets make responsible decisions.

end photo credits: U.S. Defense Meteorological Satellite Program U.S. nighttime lights, from data collected World Atlas of Artificial Sky Brightness Istituto di Scienza e Tecnologia dell'Inquinamento Luminoso U.S. nighttime lights, derived from DMSP data (above) NASA Earth Observatory Chicagoland at night, photographed from the International Space Station, October 2003 All other photos & graphics: Illinois Coalition for Responsible Outdoor Lighting all rights reserved.