Glossary

A

Ambient Light

Electric and/or natural lighting throughout a space that produces uniform general illumination.


B

Bollard

A short pole used to close a road or path to vehicles above a certain width or to provide decoravite lighting to an area.

Bracket

Any horizontally projecting support for an overhanging weight, as a corbel, cantilever, or console.


C

Cut-off angle

The critical viewing angle beyond which a source can no longer be seen because of an obstruction (such as a baffle or overhang).


F

Fixture

Informal substitute term for luminaire.fluorescentA discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light.


I

IALD

International Association of Lighting Designers.

IESNA

Illuminating Engineering Society of North America.

Indirect sources

Surfaces which, after being illuminated by other sources (direct sources such as the sun, sky, or electric light, or other indirect sources), have measurable luminance and, in turn, become sources themselves.

Isolux line

A line plotted on any appropriate set of coordinates to show all the points on a surface where the daylight illuminance is the same. A series of such lines for various illuminance values is called an isolux.


L

Lamp

An electrically energized source of light, commonly called a bulb or tube.

Lamp post

A post (generally a pole) supporting a lamp or lantern for lighting a street, park, etc.

LED

A semiconductor diode that emits light when a voltage is applied to it and that is used especially in electronic devices.

Light

Radiant energy that is capable of exciting the retina and producing a visual sensation. The visible portion of the electromagnetic spectrum (light) extends from about 0.38 to 0.77 microns.

Luminaire

A complete lighting unit, consisting of a lamp or lamps together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to as a “fixture.”

Luminance

The luminous intensity of a surface in a given direction per unit area of that surface as viewed from that direction; often incorrectly referred to as “brightness.”

P


Pergola

A frame in a garden that climbing plants can grow over and which you can walk through.