Considerations - Compact Fluorescent Lamps

Compact fluorescent (or fluourescent, or CF) lamps or bulbs are a great way to reduce your energy bill.

Traditional bulbs are called incandescent, and rely on running current through a filament to cause it to glow. Fluourescent lamps work by sending current through a gas, and it's the gas that glows; a coating inside the bulb turns the glowing gas into the light we see. This is a more efficient means of turning electricity into light. Wikipedia has an excellent entry on the technical details of how CF lamps work.

Fluorescent tubes have been in use for a long time, and are a proven efficient light. Compact fluorescent bulbs put the same technology into a spiral tube attached to a regular light socket.

Some things to consider when shopping for CF bulbs:

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CF bulbs are more efficient than incandescent bulbs, which makes the usual way of gauging the brightness of a bulb - by it's power consumption - inaccurate.

A standard measure of light produced by a light source is lumens. The table below correlates typical bulb watts, lumens, and the equivalent watts to get that much light using a compact fluorescent bulb:

Incandescent Watts Lumens Compact Fluorescent Watts
40 W 600 8–9 W
60 W 900 11–15 W
75 W 1125 18–20 W
100 W 1500 22–25 W

So where you would have wanted a 60 watt bulb (in a lamp in the living room, for example), you'd be looking for a CF bulb around 13 watts.

This table makes it easy to see the energy savings of CF lamps.

Startup Time

Incandescent bulbs glow at their full brightness as soon as they are switched on; CF bulbs can take a moment to start glowing, and then take additional time before they reach their full brightness.

Older CF bulbs use magnetic ballasts; newer bulbs use an electronic ballast. The newer (and generally more expensive) bulbs start faster, but they also don't last as long.

The difference in startup time can be significant - ranging from almost instant to almost 3 seconds. In a home, most people would become frustrated with a lighting system that took 3 seconds from the time you threw the switch to when the bulb came on.


A few years ago, these bulbs were $10 or more each. Now, you can find them almost anywhere that sells regular bulbs (including hardware stores and grocery stores) for just a couple of dollars. But there are still some reasons to pay for better bulbs.

Startup time, for one - more expensive bulbs tend to have better electronics and will start to glow more quickly.

Color Temperature

Typical household incandescent lights are what is known as "soft white". Other common types are "cool white" and "full specturm". These terms refer to the color temperature of the light, a term that basically describes what colour the light looks like. (It's more complex than that; click the link for a full description).

CF lights are available in "warm white" (2700K), "soft white" (3500k), "cool white" (4100k), and "daylight" (around 6400k). The higher the number, the less yellow and more blue the light.


CF bulbs work better in warmer temperatures.

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