Outdoor Lighting Glossary

Come across a lighting word you aren't sure of? Completely new to the world of lighting? We feel your pain! Here you will find a collection of terms and concepts that should help to make your life easier.

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Select the first letter of the word from the list above to jump to appropriate section of the glossary.

IESNA - Abbreviation for Illumination Engineering Society of North America.

Illuminance - A photometric term that quantifies light incident on a surface or plane. Illuminance is commonly referred to as light level. it is expressed as lumens per square foot (footcandles), or lumens per square meter (lux).

Illumination - The lighting in an area, or the result of the use of light. Also, the intensity of light per unit of area, sometimes called "illuminance"; usually measured in footcandles.

Incandescent Lamp - A lamp in which light is produced by a filament heated to incandescence by an electric current

Indirect Lighting - Luminaires that distribute 90-to-100 percent of their light upward to be reflected by the ceiling.

Infrared - Radiant energy with wavelengths between 770 and one million nanometers, i.e., longer than the wavelengths of visible light. Applications include photography, heat lamps, industrial drying, and medical therapy.

Instant Start Fluorescent Lamp - A fluorescent lamp designed for starting by a high voltage without preheating of the electrodes

Inverse Square Law - The law stating that the illuminance at a point on a surface varies directly with the intensity of a point source, and inversely as the square of the distance between the source and the point. If the surface at the point is normal to the direction of the incident light, the law is expressed by fc=cp/d2.

Isolux Chart - A series of lines plotted on any appropriate set of coordinates, each line connecting all the points on a surface having the same illumination.