Trespass Issues



The Illuminating Engineering Society of North America (IESNA, or IES) provides classifications for luminaires according to their glare control and high-angle brightness. These classification, along with their benefits and limitations, are described in the cutoff classifications.
Light Trespass or Spill Light - the light that illuminates surfaces beyond the property line. An example is the light on a bedroom wall coming through the window from the ball field across the street.
Glare - simply the excessive brightness experienced by looking directly into a light fixture.
Sky Glow or Light Pollution - a condition where the night sky is illuminated when upwardly directed light reflects off particles in the atmosphere, such as moisture, dust, or smog. 
Energy Usage - The electrical energy consumed by a typical outdoor luminaire represents its single largest expense-- more than the initial price and maintenance costs combined. Selecting luminaires that direct more light in the intended direction, and less into the sky or toward neighboring property often can reduce lighting energy.  Reducing wasted light saves energy.

Lithonia Lighting uses Nighttime Friendly to identify products that reduce negative impacts on the nighttime environment. Products designated with the Nighttime Friendly logo have no uplight, meet the IESNA definition for full cutoff optics and reduce high angle brightness. These measures of luminaire performance are consistent with sustainability standards for light pollution reduction. For applications where there is a concern with light trespass on neighboring properties, consider products that limit light behind the pole, such as the Type 4 sharp cutoff optical system or house side shielding.