LEDs,
or light-emitting diodes, are a form of solid-state lighting that is
extremely efficient and long-lasting. While incandescent and fluorescent
lights consist of filaments in glass bulbs or bulbs that contain gases,
LEDs consist of small capsules or lenses in which tiny chips are placed
on heat-conducting material.
Size and Efficiency
LEDs
measure from 3 to 8 mm long and can be used singly or as part of an
array. The small size and low profile of LEDs allow them to be used in
spaces that are too small for other light bulbs. In addition, because
LEDs give off light in a specific direction,
they
are more efficient in application than incandescent and fluorescent
bulbs, which waste energy by emitting light in all directions.
Long Life
The
life of a high-power white LED is projected to be from 35,000 to 50,000
and up to 70,000 hours in some cases , compared to 750 to 2,000 hours
for an incandescent bulb, 8,000 to 10,000 hours for a compact
fluorescent and 20,000 to 30,000 hours for a linear fluorescent bulb.
LED life times are rated differently than conventional lights, which go
out when the filament breaks. Typical lifetime is defined as the average
number of hours until light falls to
70 percent of initial brightness, in lumens. LEDs
typically just fade gradually.
Lower Temperatures
Conventional
light bulbs waste most of their energy as heat. For example, an
incandescent bulb gives off 90 percent of its energy as heat, while a
compact fluorescent bulb wastes 80 percent as heat. LEDs remain cool. In
addition, since they contain no glass components, they are not
vulnerable to vibration or breakage like conventional bulbs. LEDs are
thus better suited for use in areas like sports facilities and
high-crime locations.
Energy Star LEDs
Poorly designed LEDs
may not be long-lasting or efficient. LEDs that are Energy Star
qualified should provide stable light output over their projected
lifetime. The light should be of excellent color, with a brightness at
least as great as conventional light sources and efficiency at least as
great as fluorescent lighting. The LEDs should also light up instantly
when turned on, should not flicker when dimmed and should not consume
any power when turned off.
