www.illinoislighting.org presentation, august, 2008 click to begin
TRANSCRIPT
www.illinoislighting.org 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© 2008 www.illinoislighting.org
More than 80% of Americans live in urban areas.
Urban areaswhich tend tobe dominatedby manmade
light.
Since earliest times, humans have tried to createlight, to drive back the frightening dark.
But modern technology has allowed us to takethe light of a few campfires, and multiply
it billions of times over.
Our primitive fears of thedark, and our headstrong
drive to extend ourdaytime activities,
has led us to the pointwhere our nighttimeis flooded with light.
Star-filled skies, whichinspired countless
generations
Star-filled skies, whichinspired countless
generationshave faded to pale,
endless twilight.
Star-filled skies, whichinspired countless
generationshave faded to pale,
endless twilight.
Will our children,or theirs,
ever witness themagnificence of
the universe above them?
A daily cycle of lightand dark has provided
a pulse to living organisms on Earthsince 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?
Where does the waste come from?
• From operating lights when they’re 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 they’re 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 toplaces other than where they’re meant to illuminate.
Answer: Use light fixtures which put the light only where it is needed.
Many common fixtures send their light output toplaces other than where they’re meant to illuminate.
This directly wastes a large percentage of theenergy, and can create hazardous, unsightly glare.
Answer: Use light fixtures which put the lightonly where it is needed.
Wasteful “torch” fixtures Downward focused fixtures
Answer: Use light fixtures which put the lightonly where it is needed.
Hanging fixtures Recessed fixtures
Answer: Use light fixtures which put the lightonly where it is needed.
Globe-top fixtures Downward focused fixtures
Answer: Use light fixtures which put the lightonly where it is needed.
If all of a fixture’s light output is focused on the areato 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 lightonly where it is needed.
But we can see the direct glare from this light, andothers all the way down the street, because theywastefully send their output where it isn’t needed.
The green linesindicate the zone which
this street lamp isintended toilluminate.
Answer: Illuminate only to the levels needed.
When it comes to nighttime lighting,more isn’t necessarily better.It can just mean more power
consumption, and more glare.
Chicagoland at night from Earth orbit.
Years after the City of Chicagocompleted its massive
installation of thousands ofnew street and alley lights tocombat crime, the City’s own
studies found no resultingdecrease in street crime.
Answer: Operate lighting only when needed.
Much outdoor lighting serves the needs of activitieswhich do not take place over the entire night.
By shutting of lighting during non-use hours, orreducing it to safety/security levels, tremendous
energy savings can be achieved.
Auto dealer with all lot lights on after closing Auto dealer with lights down to securitylevel after closing
The future is up to us to shape.
Let’s make responsible decisions.
end
photo credits:
U.S. Defense Meteorological Satellite ProgramU.S. nighttime lights, from data collected 1994-1995
World Atlas of Artificial Sky BrightnessIstituto di Scienza e Tecnologia dell'Inquinamento Luminoso U.S. nighttime lights, derived from DMSP data (above)
NASA Earth ObservatoryChicagoland at night, photographed from the InternationalSpace Station, October 2003
All other photos & graphics: Illinois Coalition for Responsible Outdoor Lightingwww.illinoislighting.org, all rights reserved.