Light Pollution

In designing any outdoor lighting system, we should all be aware of light pollution.

Light pollution is artificial light that is obtrusive, excessive and misdirected. Excessive light pollution can result in disrupted ecosystems, interference with astronomical research, and wasted energy.

There are three main types of light pollution: sky-glow, glare and light trespass. 

Sky-glow is the glow effect seen over any large city. It is the combination of unshielded upward directional light and reflected light. An example would be poorly executed architectural lighting which was not locked into adjustment properly.


Glare is light from an unshielded light source. This can be very unsafe. Glare can limit a person’s vision. For instance, a flood light controlled by a motion sensor that is facing directly toward oncoming traffic from a driveway will create glare. A driver could be distracted with light projecting in their eyes, causing obstructed vision and a potential accident. Attaching a shield or simply adjusting the fixture can solve this safety hazard.


The third type of light pollution is light trespass. Light trespass is light that accidentally or purposely intrudes from one property to another. This happens frequently in landscape lighting. Often, misdirected wall wash, down lighting from trees, and/or over-lamped up lighting can spill over into neighboring properties. An old landscape lighting design technique was to position ground mounted up lights from one property to illuminate the back sides of tall trees on another. This technique is still used today. I would highly recommend that a contractor seek the permission of the neighboring property owner before proceeding. Written permission is always suggested. A specific switch for this technique is also advisable. A switch will control this bank of special effect lighting for evenings when your client is entertaining. When done properly, this technique can allow all parties involved a very pleasant experience.

In summary, light pollution can be controlled. Using the proper lamp or integrated fixture that is shielded can significantly reduce glare. Proper aiming, Kelvin temperature, lenses and louver selection can also cut down on light pollution.  

For more information on light pollution,

Kevin SmithComment