How to Save Energy and the Night Sky

Good outdoor lighting design enhances safety, security and beauty

Photo of Milky WayLook around at night and you’ll find many examples of bad outdoor lighting.  Too much glare makes it difficult to see things.  Continuously lighting an area can actually increase crime, and shining light everywhere can anger your neighbors and destroy our ability to see the infinite beauty of the night sky.  New lighting technology that uses light emitting diodes (LEDs) has the ability to fix these problems.  But if done wrong, LED lighting can make these problems much worse.

The key to getting it right is good lighting design.  Much outdoor lighting used at night is uncontrolled, inefficient, overly bright, poorly targeted, improperly shielded, and, in many cases, unnecessary. We have the power to change this.  Good lighting design can save significant amounts of energy, reduce glare and recapture our view of the night sky. 

Here’s how to get it right:

1.) Good Lighting Controls – Studies have shown that while more light may make you feel safer, it does not necessarily result in less crime.  More light could even increase crime.  Rather than attracting thieves by shining a light all night on the things you want to protect, your property is more likely to be protected by a light that instantly turns on whenever motion is detected.    Motion sensors also conveniently turn lights on automatically when you come home or are working in an area that is being illuminated.  Make sure you use high quality motion sensors that are properly adjusted to prevent the lights from annoyingly turning off while you still need them, or turning on unnecessarily every time a car passes in front of your house.

2.) Shine Light Only Where You Need It - Unwanted light shining in your window or your neighbor’s window, especially point-source LED lighting, can be extremely bothersome.  Proper shielding will keep the light directed only on your property, and will avoid drowning out the night sky.    Except for possibly flag lights, there is no reason to shine lights up into the night sky.  It wastes energy and destroys our ability to see the incredible universe that surrounds us. The light should point down and not be visible from above or off in the distance.

3.) Avoid Glare Bombs - Our eyes constrict to the brightest point source of light. It then takes more light to see the same amount of detail.  An ideal lighting design will illuminate only the things we want to see without us seeing the actual source of that light. 

4.) Minimize Blue Light Emissions - Blue wavelengths are beneficial during daylight hours because they boost attention, reaction times and mood, but they can be disruptive at night. A recent American Medical Association report expressed concern about exposure to blue light from outdoor lighting and recommended shielding all outdoor light fixtures and only using lighting with 3000°K color temperature or below. Think of the color temperature as the temperature at which an object starts to glow.  If something is red hot, it has a temperature of 1000° Kelvin (K) or less.  An object starts to appear white hot if it is heated up to 1480°K or more.  By the time it reaches 3000°K or more it begins to turn blue.


Dark Sky Association SealThe International Dark-Sky Association website includes a guide to choosing lighting fixtures. When shopping, look for the association’s Fixture Seal of Approval which certifies outdoor fixtures as being dark-sky friendly. Products in this program are required to be fully shielded and to minimize the amount of blue light in the night environment.

 (Sources: International Dark-Sky Association, Harvard Health Letter, American Medical Association)