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TECHNICAL INFORMATION
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Watt
:
•
noun
•
unit
equivalent to Amps
x
Volts.
Ampere
:
•noun•
unit of electric current, commonly shortened to “Amp”
Luminous Efficacy
:
•
noun
•
measure of how efficiently a light source produces visible light
Volt
:
•noun•
unit of electromotive force, difference of potential that would drive one ampere of current against one
ohm of resistance
Candela
:
•noun•
unit of measure equal to the intensity of light at a single point within a light pattern
Lumen
:
•noun•
unit of measure equal to the
total amount of light emitted
Iso-Candela Scan
:
•
noun
•
method of measuring and quantifying total light output of a light source within a standard area
Surprisingly, Watts are not a measure of light at all—they are a measure of energy consumed. Traditionally, with incan-
descent bulbs, the more power consumed the more light emitted, so light output was equated by power consump-
tion. However, when dealing with LEDs, more power does not necessarily mean more light. LEDs consume
far
less
power than incandescent bulbs. An incandescent bulb drawing 100W may light a single room, while an LED lamp
drawing 100W could light up several large rooms.
Here’s another way to understand this idea. Let’s equate energy consumption of a lamp to gasoline consumption in
a car. Let’s assume Watts are the Gas, Light Output is the Distance Traveled, and the Lamp is the Car.
When asking how far away a destination may be, do we ask, “How many gallons away is that town?” No. Why
not? Because, we know that different cars get different gas mileages. If all cars achieved the same gas mileage we
could estimate distance by the amount of gallons of gas consumed. But with technology constantly making engines
more fuel efficient, it would be inaccurate
to measure distance by gallons of gasoline
consumed.
Lights operate on this same principle. Before the advent of low current draw LED lighting, it was relatively accurate
to measure light output by power consumed because most bulbs had identical light efficacy, or in terms of our cars,
they traveled the same miles per gallon. Now, LED lighting has revolutionized the traditional power consumption
to light ratios of incandescent lighting. LED lighting, when properly engineered, can produce far more light than an
incandescent bulb drawing the same amount of power. In other words, LED lamps, are the hybrid car, getting 100
miles per gallon, and incandescent bulbs are the heavy 1963 Ford Galaxy, getting 8 miles per gallon.
The Problem With Watts:
Why Watts Don’t Mean What They Used To
Definitions
WATTS
= POWER CONSUMED
NOT
TOTAL LIGHT
LED Technology
is new and exciting. As lighting technology
continues to improve, so does the importance of developing
an understanding of technical terms and ideas related to
LED lighting technology.