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Welcome to the Light Pollution Pages of the Calgary Centre
of the Royal Astronomical Society of Canada (RASC)
We all need light for safety, security and convenience. All of these uses can be
achieved more effectively and cheaply if we avoid and reduce light pollution.
What is Light Pollution?
Light pollution is light that shines where it is not needed or wanted. It has
several forms: glare, light trespass, over-lighting, and uplight. Light pollution
causes energy waste and sky glow. Light pollution is easily recognized as:
light that shines onto your property or into your home; glary light from poorly
aimed fixtures or that is too bright for its surroundings; and light that shines up
into the sky.
Responsible Lighting is healthy lighting. Use only the right amount of light,
shining where it is needed, without negatively impacting visibility or others' safety
and enjoyment.
Photo: sky glow over Calgary, Alberta
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Links to Fast Facts About Light Pollution:
Page last updated May 2, 2011
Top 5 Light Pollution Misconceptions
- Light at night prevents crime.
- More light improves visibility.
- You can get good illumination by "throwing" light from HERE
to OVER THERE
- Light pollution is not really pollution because it goes away if you turn off the lights.
- Light pollution is only a problem for astronomers.
Visit our Light Pollution Main Site to
find out more about these misconceptions and what the real answers are.
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The Golden Rules of Good Lighting
Use fully shielded fixtures and aim lights downward to keep your light on your
own property. This will solve most light trespass and glare problems and it will
reduce sky glow. Turn lights off when not needed (like your parents taught you!). Most exterior
building lights, area lights, and illuminated signs can be turned off overnight when
very few people are out. This will not affect security and it will save energy. Use the right amount of light. Too much light actually reduces your ability
to see by making adjacent areas appear dimmer. This can be hazardous. Good lighting
uses carefully-aimed, shielded, low intensity lighting to create more uniform illumination.
This provides for better illumination that enhances visibility and reduces energy consumption.
See "What You Can Do" on our Light Pollution Main Site for
more information.
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The 3 E's of Responsible Nighttime Lighting: Efficiency, Efficiency, Efficiency
Efficient Lamp:
Choose the most efficient bulb type that
meets the goals of your application. Sometimes an inefficient incandescent bulb
is the best choice if you want relatively low illumination levels and rapid "on"
capability as in a residential motion sensor fixture. Don't choose an efficient
lamp if it won't properly do the job.
Efficient Fixture:
An efficient bulb is no good if the fixture it is used in allows light to be sprayed
everywhere. Full cutoff fixture designs mean that the light is directed where it is
needed and none is wasted by creating glare.
Efficient Application:
Think how the light is to be used. All-night security lights have been shown to have
minimal effect on crime levels so motion sensor fixtures are a more appropriate choice.
Choose the appropriate light output - remember, sometimes less is more; don't overlight,
it can create bigger problems than it solves. Creating bright "pools" of light with
strong contrasts to unlit areas allows hazards in the shadows to remain undetected.
Sometimes the best solution is to use no light at all.
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Calgary Roads' Streetlight Retrofit Program is a Win, Win, Win for Calgary.
The City of Calgary is retrofitting more than 40,000 wasteful, semi-cutoff, residential
streetlights with full cutoff ones. By using the more efficient design, they are able to
use lower wattage lamps to safely illuminate roadways. Calgarians win, win, win:
City taxpayers will save $2 million in electricity costs per year. The lower CO2 emissions and lower light pollution levels are good for the environment. Low-glare light fixtures mean that Calgary roadways will be safer for drivers and pedestrians.
See "Light and Traffic Safety" and "Community Retrofits" on our Light Pollution Main Site.
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Can We Do More to Prevent Light Pollution?
Yes! Light pollution is preventable. We can all do our part at home, at work, at play and where we shop.
City of Calgary Bylaws provide a neighbourly code of conduct for its citizens.
By implementing an outdoor lighting bylaw for Calgary we can:
- reduce negative local environmental and human lifestyle impacts,
- help conserve energy,
- ensure safe lighting,
- protect investment in astronomical facilities, and
- enshrine civic aesthetic guidelines
Calgarians have many bylaws covering billboards, unsightly premises and noise - we want a clean,
friendly and safe city - now we just need to extend those concepts to the other 12
hours of the day.
Thank you for taking the time to visit our summary website.
There are more details and interesting facts on our Light Pollution Main Site.
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Light and Crime
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Although many people feel that all-night lighting prevents crime, data do not
show a strong relationship between lighting and crime rate. Like many police forces
across the world, the City of Calgary Police Service has concluded that when and where
crimes occur are not related to the amount of darkness available. Calgary crime statistics
show that most break-ins occur when a property is unoccupied (homes during the day; businesses
at night, despite "security" lights).
"Security" lights can create a false sense of security, and poorly designed "security"
lights can obscure criminal activity, both of which may ultimately be detrimental
to personal safety.
"Security" lights do not replace human vigilance.
See "Light and Crime" on our Light Pollution Main Site.
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Light and Health
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The body needs dark nights to allow key chemical reactions to take place.
Left: Daily variation in prepubertal girls (I-1, I-2) and early pubertal girls (II)
of Follicle-Stimulating Hormone (FSH), a key controller of certain processes in puberty
(from Mitamura, Yano, Suzuki, Ito, Makita and Okuno, 2000 J Clin Endocrinol Metab Mar;85(3)
:1074-80 ).
See "Light and Health" on our Light Pollution Main Site.
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Light and Animals
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There are a number of well-documented adverse effects of nighttime lighting on wildlife,
including migrating birds colliding with lit structures at night, changes in reproductive
capability and behaviour modifications. Some animals shun lit areas while others take advantage
of the light to forage or hunt at the expense of other species. Everyone has seen moths
clustering around outdoor lights - attracted to the brightness when they should be looking
for a mate. Many large shy predators avoid lit areas altogether.
See "Light and Animals" on our Light Pollution Main Site.
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Light and Greenhouse Gases
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Because Alberta's electricity is primarily generated by burning coal and natural gas,
an all-night 100 Watt porch light is responsible for approximately 390 kg of CO2 emissions
in a year. To meet the Kyoto Accord's goals in 2002 simply by conserving electricity, each
Albertan would need to turn off the equivalent of 11 such night lights.
Choosing the most efficient lamp that properly does the job allows you to minimise
electricity use and hence CO2.
See "Light and Greenhouse Gases" on our Light Pollution Main Site.
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See "Light and Astronomy" on our Light Pollution Main Site.
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