How Light Pollution Affects Choices for Landscape Lighting

Resolutions approved June 15, 2009 by the American Medical Association

RESOLVED That our AMA advocate that all future outdoor lighting be of energy efficient designs to reduce waste of energy and production of greenhouse gasses that result from this wasted energy use, and be it further

RESOLVED That our AMA develop and enact a policy that supports light pollution reduction efforts and glare reduction efforts at both the national and state levels; and be it further

RESOLVED That our AMA support that all future streetlights will be of a fully shielded design or similar non-glare design to improve the safety of our roadways for all, but especially vision impaired and older drivers.

Light pollution noted by the American Medical Association is a problem for vision necessary for safe driving and walking in public places, as well as for global climate change -- through the waste of energy.

Light pollution sounds like a trivial issue until people look into it a bit deeper.  Health is impacted by circadian rhythms.  Plants are affected by the amount of light they receive. Animals, insects and other life forms are affected by light.  We are ALL affected by light -- both positively and negatively.  So, if you know that light is a problem and would like to do something with your own lights to make them less of a problem -- here is a basic guideline for light design that minimizes night sky light pollution.
 

• Fix Your Fixtures -- Ensure that you are not part of the problem by checking outdoor light fixtures around your house and/or business. Ensure that the lights do not shine outwards and unnecessarily at night. Install the lights high on your home or building, have them pointed downwards and use full cutoff luminaires to better control and direct the light to where it is needed and not to where it is unwanted.
  
   
• The picture at the right shows the good light being placed higher on the house and pointed downwards, this eliminates the shadow regions near a light that can hide a bad guy. Correct those lights that do.
  
  
  
  Remember, the basic goal for lighting is this:
  
  
  
  no light should be emitted above the light source's horizontal plane.

Landscape Lighting and Trees

Landscape Lighting -- Using lights to illuminate trees, houses and land is strongly discouraged. Not only does this pure act of vanity contribute to glare and light trespass,  but it also may harm the plants or trees that are being lit.

Many trees adjust their growth based on light levels. Artificially changing the light levels alters the plant's ability to respond to the changing seasons.

However, if you still insist on installing landscape lighting, you should at least focus the fixtures downward so that its angle does not exceed 45 degrees from the ground to reduce glare and light trespass and use lamps of the lowest wattage lamps possible.

You can save money by conrolling your landscape lighting by a timer, so that the lights turn off by 10 p.m.

While solar landscape lighting reduces energy use, it has a unique problem --  solar landscape lights can not be turned off, so they stay on all night or until their batteries run down. As such, they are another unneccessary light source.

By pointing landscape lighting downward, you actually optimize the human use of the light... we're only engaged with about six feet of vertical space for the most part... and by directing light into that zone, for appropriate task lighting, you can enhance quality of life while minimizing energy and light pollution.

Visit the International Dark Sky Association for a wealth of outdoor lighting information.