Low Energy Bulbs


A compact fluorescent lamp (CFL), also known as an energy saving lightbulb, is a type of fluorescent which fits into a standard light bulb socket.

In a CFL, an electrical current flows through the gas, causing it to emit ultraviolet light, which then excites a white phosphor coating on the inside of the tube. This emits visible light.

In comparison to incandescent light bulbs, CFLs have a longer rated life and use less electricity. CFLs might save enough money in electricity costs to make up for their higher initial price within about 500 hours of use.

However, incandescent bulbs are dropping in price, as they reach us in larger numbers from the Far East.

CFLs have steadily become more popular since they were introduced in the 1980s. They have improved, and now they flicker much less than before. When new, they also warm up more quickly.

CFLs are produced for both AC and DC.

For a given light output, CFLs use about 20% of the power of ordinary bulbs.

In addition to the above savings on energy costs, CFLs last approximately 8 to 15 times longer than a normal bulb.

The output of a bulb's light can be colour-coded by the "colour temperature", in Kelvins:

2700K: Warm White or soft white
2950K: White, bright white or medium white
4000K: Cool white
5000K: Daylight

CFLs are also produced in other colors:

Red, green, orange, blue, and pink; mainly for novelty purposes
Blue for phototherapy
Yellow for outdoor lighting, because it does not attract insects
Blacklight (UV light) for special effects

A CFL is a gas discharge lamp, so will not generate all frequencies of visible light. The actual color you get is a design compromise. Normal bulbs don't produce "daylight" either; they usually lack the bluer frequencies.

To some consumers, fluorescent lights provide a harsh and garish light compared with the normal bulbs, which is why many people do not buy them. They cost more, are sometimes slow to warm up, especially if elderly, and the failure rate is considerable, especially in "buy six, get six free" deals in the press, where one or two of the bulbs often don't work.

Nevertheless, switching over to CFLs in the right situations will save electricity and money.

CFLs contain small amounts of mercury. Correct disposal is important. It's not clear to me (yet) what I should do with spent CFLs.

Back to top

Energy Policy
Fuel to Electricity
Nuclear Power
Wind -
big turbines
Wind -
small turbines
Diversity Website