Light Pollution - And the Solution

Update 29 November 2005

Light pollution is now becoming a global issue. Astronomers are concerned about the disappearing stars in the night sky due to unnecessary scattered uplight from poorly designed artificial light fixtures. Concerns are raised about the wasted energy and money and effects on the environment and health.

While many town planners  are beginning to take notice there is still a long way to go.
Far too many business, advertising and security light fixtures are still being installed without due consideration to the choice of the correct fixture for the task.

The result is unnecessary sky glow, glare and light trespass. Mostly it is due to a choice of cheap, inefficient options and a lack of awareness of better lighting options.

  Growing light pollution over Adelaide encroaches on the stars seen from 120 km north of the city. While some of this light is unavoidably reflected upward from road and other surfaces the remainder is wastefully emitted directly upward from tens of thousands of poorly shielded street lights and similarly badly aimed and unshielded advertising and security lights. This wasted light costs millions of dollars of electricity annually and injects more than 70 thousand tonnes of carbon dioxide into the atmosphere from burning fossil fuels to generate this wasted electricity. Smart lighting practices can be adopted to save power and the environment while creating a better and safer night time lighting -- and also help preserve the night sky. 

Star-trail image courtesy Justin Tillbrook

Within the the city uplight from unshielded light fixtures scatter upwards creating a pervasive sky glow obliterating all but the brightest stars. If all this wasted uplight were directed downward - where it is useful - only 6% of it would return upward due to reflections. Not only would this bring back many of the stars but improve lighting quality on the ground by reducing glare and even save on energy and money.  The lone object in the washed out sky in this image is Mars. Taken from the coast at Semaphore South looking east toward the greater metropolitan area.

Photo: Martin Lewicki



Fully shielded fixtures direct light below the horizontal toward the ground. G1 is one of the standard "cobra head" aero luminaires fitted with a flat lens that prevents light from scattering sideways and upward, avoiding glare and improving the quality of lighting. Fitted with a LPS or HPS (sodium-yellow) lamp they are efficient and make a good choice for many kinds of outdoor lighting especially roadways. They generally require closer pole spacing for more even road coverage. Examples can be seen in some council areas especially in parts of Adelaide CBD where they are replacing older glarey fixtures.

G2 is the preferred flood light fixture for areas such as car yards and parking lots. Often fitted with less efficient mercury or metal-halide (white) lamp, the design however avoids glare and light trespass without compromising security. 



These fixtures are fitted with a dome or cylindrical shaped lens that emit a substantial portion of their light uselessly sideways and upward creating glare, light trespass and sky glow. These fixtures are currently the standard on the state's arterial roads and many residential roads. B1 is the same kind of fixture as G1. However the dome shaped lens scatters some of the light inefficiently. They can easily be refitted with a flat lens as in G1 as some Councils have done to existing fixtures.

The  "flower-pot" mercury vapour lamps (B2) are a very bad choice. They are pervasive  in residential streets throughout the metropolitan area and are especially glarey, inefficient and costly to run (they have been outlawed in other countries). A far better choice would be a G1 fitted with a sodium lamp or metal halide lamp.

Intended to highlight advertising or "enhance" architecture, these light fixtures indiscriminately spray light everywhere. Billboard and business lighting, or lighting that is supposed to illuminate significant architecture as in U1, are often placed so that a substantial portion of the light completely misses its target and adds to the waste light and sky glow. Billboards should be illuminated from overhead light fixtures and buildings should be illuminated by carefully designed and aimed "spotlights". Both should be subject to curfews in late hours. Globe lights like those in U2 may look good in the daytime, but are very wasteful at night because most of their light goes sideways and up into the sky! They should never be used for street lighting. Efficient, alternative designs are available where aesthetic lighting is required.

Good lighting practice
not only gives us better quality
nighttime illumination and saves energy but
brings back the stars!

An inspirational dark sky in a deep rural setting. View looking west with the constellation Scorpius setting.
Same view  in a light polluted urban setting with unnecessary sky glow and glare from poorly designed and unshielded lamps.
Full cutoff fixtures direct light below the horizontal providing quality illumination with reduced sky glow, less glare and  returning some stars to the sky.

Examples of Good and Bad Lighting Practices
in Adelaide

ñ Fair
While the lens on this arterial road HPS lamp was designed for wide road coverage it still emits glarey sidelight that dazzles motorists.
 ñ Excellent 
Similar HPS lamp with flat "lens" that emits all its light downward creating excellent, well illuminated and glare reduced roadway. 

 ñ Bad
This inefficient 80 watt "flower-pot" mercury street lamp emits considerable amount of side-light and up-light creating a harsh glare and adding to sky glow.
 ñ Better
This more efficient semi-cutoff 50 watt HPS street lamp with reduced sidelight is a better choice.

ñ Bad
A cheap, inefficient, glarey halogen light in a Cheltenham car yard.
Quality full-cutoff fixture in a car park in Glenelg. Also seen in better car yards.

ñ Bad 
The same glarey halogen lights as above  at night with excessive light spill creating a motoring hazard.
Smiths at Croydon use quality full cutoff floodlights that reduce glare and uplight.

ñ Bad
Billboard illuminated from below loses light skyward wasting energy and adding to sky glow.
ñ Excellent
Full-cutoff down-lights aesthetically illuminate sign with minimum glare and uplight

ñ Bad
These globe lights at Charles Sturt Council car park spray wasteful amounts of light sideways and upwards.
Efficient glare-free down-lighting with box-floods. Also a good choice for car parks.

ñ Bad
This virtually naked, unshielded "security light" flood light emits very bad and glarey side-light adding a hazard for passing motorists.
ñ Good
Similar flood light light fitted with a hood that avoids annoying light trespass and reduces motoring hazards.

ñ Bad
Light-trespass from this post-top HPS lamp has been painted out by annoyed residents in Henley Beach.
Councils will shield light trespass, but usually at  your cost. This light still emits wasteful side-light and up-light in the other directions.

ñ Bad
No consideration was given to the aiming of this forward-throw light fixture at Transport SA Port Adelaide. The main beam is directed skyward!
Correct positioning of the same light fixtures properly illuminates the target area with no light emitted upwards.

ñ Bad
Walkway post-top lantern fitted HPS lamp kills off old style charm emitting glarey sidelight.
New technology highly efficient LED lights in full cutoff fixtures create a glare-free, safe and pleasant ambient light.

Woolworths roadhouse has full-cutoff floods throughout - even at the air pump station at back . very little sidelight reduces glares and utilizes most of the light,
Kentucky Fried at Welland illuminate customer car  park with low glare full-cutoff  lights. Both exterior and interior lights are turned off at close of business at the small hours to save energy.

ñ Bad
This unshielded flood light at a corner car sales yard emits glarey light far beyond the confines of the business premises, wasting light and...ð
  ...forcing  residents across the road to install heavy duty window shutters. This kind of light pollution detracts from amenity and can easily be remedied with a quality full-cutoff floods and after-hours curfew.

Sport ground with tall full cut-off floods confines light to play area preventing widespread light spill and glare that would otherwise afflict the neighbourhood.
Standard BBQ light fitted with a homemade tin hood secured with a 10cm hose clamp. Avoids light trespass, glare and waste light.

light pollution brochure
Download the ASSA Light Pollution Brochure
(273kb PDF).
Print onto two sides of a single sheet and fold to use as a handout.

Light pollution article

Light pollution links

Unless otherwise stated all images are by Martin Lewicki.
© Martin Lewicki 2003. Adelaide, South Australia

More articles by Martin Lewicki.