Lamp color temperature is rated in Kelvin
degrees, and the term is used to describe the “whiteness” of the lamp light. In
incandescent lamps, color temperature is related to the physical temperature of
the filament.
In fluorescent lamps where no hot filament
is involved, color temperature is related to the light as though the
fluorescent discharge is operating at a given color temperature. The lower the
Kelvin degrees, the “warmer” the color tone. Conversely, the higher the Kelvin
degrees, the “cooler” the color tone.
Incandescent lamps provide pleasant color
tones, bringing out the warm red flesh tones similar to those of natural light.
This is particularly true for the “soft” and “natural” white lamps.
Tungsten filament halogen lamps have a gas
filling and an inner coating that reflects heat. This keeps the filament hot
with less electricity. Their light output is “whiter.” They are more expensive
than the standard incandescent lamp.
Fluorescent lamps are available in a wide
range of “coolness” to “warmth.” Warm fluorescent lamps bring out the red
tones. Cool fluorescent lamps tend to give a person’s skin a pale appearance.
Fluorescent lamps might be marked daylight
D (very cool), cool white CW (cool), white W (moderate), warm white WW (warm).
These categories break down further into a deluxe X series (i.e., deluxe warm
white—deluxe cool white), specification SP series, and specification deluxe SPX
series.
Typical color temperature ratings for lamps
are 2800K (incandescent), 3000K (halogen), 4100K (cool white fluorescent), and
5000K (fluorescent that simulates daylight). Note that a halogen lamp
is “whiter” than a typical incandescent
lamp.Catalogs from lamp manufacturers provide detailed information about lamp
characteristics.
Fluorescent lamps and ballasts are a moving
target. In recent years, there have been dramatic improvements in both lamps
and electronic ballast efficiency.
First, the now-antiquated T12 fluorescent
lamps (40 watts) were replaced by energy-saving T8 fluorescent lamps. These
original T8 lamps are becoming a thing of the past. The latest T8 high
efficiency, energy saving (25 watts vs. 32 watts) lamps have an expected 50%
longer life than the original T8 lamps.
The newer T8 lamps use approximately 40%
less energy than the older T12 lamps. At $0.06 per kWh, one manufacturer claims
a savings of $27.00 per lamp over the life (30,000 hours) of the lamp. At $0.10
cents per kWh, the savings is said to be $45.00 per lamp over the life of the
lamp. Using the newer T8 lamps on new installations and as replacements for
existing installations makes the payback time pretty attractive.
One electronic ballast can operate up to
four lamps, whereas the older style magnetic ballast could operate only two
lamps. For a three- or four-lamp luminaire, one ballast instead of two results
in quite a saving. Some electronic ballasts can operate six lamps.
Hard to believe! You now can have reduced
power consumption and increased light output using electronic ballasts. Today’s
high-efficiency ballasts are available with efficiencies of from 98% to 99%.
