So, you’ve heard the buzz about switching to CFL to reduce your energy consumption, and in doing so help the environment and save you some money on your electricity bill. You might even have seen some of the funny coiled bulbs in stores.

But how do you know which ones to get to replace your existing incandescent bulbs?

How Many Watts?
Most CFL bulbs show the equivalent incandescent wattage on the box, but the number you really need to look for is the Lumens, which is a measurement of the light output of the bulb rather than its electrical power consumption. The Environmental Defense Fund has a great table showing incandescent wattage, CFL wattage and typical lumens values. The table also gives you a rough idea of the cost savings and the reduction in CO2 emissions over the life of the bulb.

If you’re worried about the amount of light that CFLs produce being lower than the equivalent incandescent, try upgrading to the next wattage level (as long as it is still lower than the limit on the light fitting of course). For example, if you’re replacing a 60W incandescent, you could try using a 20-25W CFL instead of the 15-19W one normally recommended.

Do CFL Bulbs Produce Cold Light?
In the past, fluorescent lights produced a cold, bluish-white light that was not very relaxing. The color of the light produced by a bulb is measured in Kelvins (it is technically a temperature). Somewhat counter-intuitively perhaps, the lower the temperature, the warmer the light!

A traditional incandescent light bulb has a color temperature of between 2800K and 3300K, so when hunting for a CFL replacement you should be looking for bulbs with a similar color temperature if you want to keep the warm light you’re used to. The cold, bluish light from older fluorescents is 4000K or above (also called daylight).

Old Fluorescents Flicker, Do CFLs?
The older, long tube fluorescent bulbs used what is called magnetic ballast to keep them lit up. That ran at the frequency of the power source (50-60Hz), which can be detected by most people as a slight flicker. This continuous flickering was also said by some to cause headaches.

The much more modern CFL bulbs use electronic ballast that operates at much higher frequencies (10-40KHz), which are well beyond the capabilities of the human eye to detect. As a result, CFLs produce what looks like a continuous, bright light. There are still a few people who claim that CFLs cause them to experience headaches, but it is unclear whether they are really caused by the bulbs, or by other factors relating to the change.

If you have had headaches when working under older fluorescents, perhaps try changing just one room first and see how it goes.

Can I Get CFL Floodlights, and Other Styles?
Yes, absolutely. You can get CFL bulbs now in most of the same form factors as regular incandescent lights.

I have flood lights, like the one shown on the right, in almost all the ceiling can light fixtures around the house, I use “standard” ones in most of the other lights around the house, and a couple of low wattage candle bulbs in the nightlight fixture that our HOA requires we keep on all night (it is connected to a light sensor to make sure it is only on after dark).

I Have a Dimmer Switch, Can I Still Use CFLs?
Yes, you can switch to CFLs even when your lights are connected to a dimmer switch, but you’ll need to make sure you select CFLs that are compatible with dimmers (they will say so on the box). Not all CFLs can be used with dimmer switches, so make sure you check - if in doubt, ask in the store.

Do They Really Last Longer?
Yes, they really do have a much longer life than incandescent bulbs. The technology in an incandescent bulb doesn’t lend itself to a long life, especially if you switch them on and off a lot. An incandescent bulb makes light by heating a thin filament of metal (by passing electrical current through it). Repeated heating and cooling of that metal filament makes it weaker and eventually it fails.

CFLs do not have any filament to fail. Instead, they have the electronics in the ballast which will eventually fail, but people have had fluorescent lights last much longer than the life expectancy on the box. You might find some fail early, but in general they will last longer than the life expectancy on the box.

Do They Contain Mercury? Is That Safe?
The one down side to the environmental story of CFLs is the fact that they do contain a very small amount of mercury. In normal use they are perfectly safe though as the mercury is sealed inside the bulb. The only times you need to think about it are if you break one, and when one fails.

If you break the glass on a CFL, you might want to open some windows to ventilate the space, and leave the room for a little while to let the small amount of mercury vapour disperse. Obviously, much like any bulb, when disposing of it be careful of the sharp glass. Fluorescent bulbs have a tendency to shatter into small pieces of glass, so be careful to get them all!

When a CFL fails, you will need to dispose of it properly and not just throw it in the garbage. They do count as hazardous waste, which makes it illegal in most places to just throw them out. Many hardware stores will take them back for safe disposal/recycling. If you can’t find one that does, try asking you garbage collection service or city authorities how to dispose of them.

Tags: candle, cfl, dimmer, floodlight

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