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Flashcards in Lighting Deck (16)
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1

Efficacy

A rating based upon the lumens per watt consumed, reflecting the energy efficiency of a lamp. Lumens divided by wattage. The higher the number, the more efficient.

2

IES / IESNA

Illuminating Engineering Society / Illuminating Engineering Society of North America

3

Luminous Flux

It is the density of light at any given point on a surface. Measured in footcandles or lux
E (illuminance) = Ø (incident flux) / A (area)
Density of flux incident on a surface is measured perpendicular to the surface.

4

Luminance

Light that is reflected from a surface in a given direction (back towards the eyes). Properly defined as intensity of flux leaving a surface in a given direction.
Measured in candela per square foot = Intensity / Area

5

Luminous exitance

Total quantity of light emitted, reflected or transmitted in all directions from a surface. Properly defined as density of flux leaving a surface.
Measured in lumens per square foot.
Luminous exitance = Departing luminous flux / Area

6

Intensity

Light emitted in a specific direction by a source properly called luminous intensity. Measured in candela.

7

Flux

It is lighting emitted in all directions by a source. Properly called luminous flux and defined as time rate flow of light.
Measured in lumens (lm)

8

ADAAG

Americans with Disabilities Act Accessibility Guidelines

9

Light

Visually evaluated radiant energy

10

Layers of light

Task, focal/display, ambient, decorative

11

CRI

Color rendering index. Higher the number, better the rendering. 1-100.

12

CT

Color temperature

13

CCT

Correlated color temperature

14

Illuminance

The total amount of light falling on a surface, measured in lux (lx) or foot-candle (fc).

15

HID

high intensity discharge

16

SSL

solid state lighting