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.
Lithonia Lighting uses Nighttime
Friendly™ to identify products that reduce negative impacts on
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.
Light Trespass or Spill
- 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
- simply the excessive
brightness experienced by looking directly into a light fixture.
Sky Glow or Light
condition where the night sky is illuminated when upwardly directed
light reflects off particles in the atmosphere, such as moisture,
dust, or smog.
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.