A Refresher on Light Distributions
Light distributions tell you
the pattern of light that comes out of the fixture and forms on the ground. Determined by the
Illuminating Engineering Society (IES), light distributions give landscape architects and lighting
designers a tool to properly light a site.
Caption: Light distributions
tell you the pattern of light that comes out of the fixture and forms on the ground.
Since a site may have multiple lighting needs, from
broadly lighting a parking lot, for example, to lighting a narrow pathway, multiple light distributions
allow designers to target the need with the correct distribution. Landscape Forms Lighting Sales Specialist
Chad Gleesing explains that a lighting product line with multiple distributions “give designers peace of
mind. They have flexibility to use the same light product from the building to the parking lot and maintain
a design aesthetic.” How a distribution throws light is important in eliminating trespass and wasted light.
There are five light distributions. Gleesing explains each and the types of applications for which they
would be specified.
Type I and Type II
Type I and Type II are similar in that they throw a narrow and linear light pattern.
These distributions are used mainly on pathways, walkways, and sidewalks where a side-to-side throw of light
is desired. Type I and Type II distributions are great for spacing and keeping light on walkways and out of
the landscape. Type II distribution has a little more forward throw compared to Type I.
Shown here is a 20’-tall Torres area light in a Type II distribution.
Type III offers side-to-side light but also more forward throw than a Type I or Type
II distribution. This distribution is used in areas that are larger and need more coverage. Because it has
both side-to-side and forward throw, applications for this distribution are versatile and broad. It can be
used along the edges of a site because its asymmetric pattern throws light forward and helps reduce
Shown here is a 14’-tall Ashbery area light in a Type III distribution.
Type IV typically features the most forward throw among the asymmetric
distributions. This distribution is often used in places such as parking lots where there may be limited
pole locations and a need to illuminate far-reaching areas.
Shown here is a 16’-tall LEO area light in a Type IV distribution.
Type V is a symmetric distribution that throws light equally in all directions. It
is often used on a fixture in the center of an area and in catenary applications. Type V can be circular or
Shown here is a 10’-tall Motive area light in a Type V distribution.
Mounting Heights, Types, and Impact on Illumination
Both distribution and fixture height come into play when properly lighting an area.
That is why fixtures with multiple distributions, pole heights, and lumen outputs are important. The IES has
recommendations on uniformity for different applications, and the heights you use will affect those