Compact fluorescent light bulbs, or CFLs, have been generally available and affordable for consumers for quite a few years now. I've been using them for about ten years, and they have steadily improved during that time. Needless to say, they aren't perfect, but there are many ways to use them successfully.

It is not simple to make a new kind of light bulb which can replace the simple incandescent bulb in all situations and still provide significant energy savings. Some tradeoffs are necessary.

The very first fluorescent bulb I used as a retrofit in an existing light fixture was a large circular tube attached to a screw-in base in the center hub, known as a Circline. The tube was large: about a foot in diameter and an inch thick. Designed for large floor lamps and lamp shades, it used 25 watts and provided the equivalent of a 50 or 60 watt incandescent bulb (saving half the energy). An improvement, but not compact. I still have two of them in use.

The energy savings from fluorescents is significant. My first CFLs used about a third of the energy as an incandescent bulb for the same amount of light. For example, my first 20-watt CFL produced the same amount of light as a 60-watt incandescent. Now they usually use a quarter of the energy as an incandescent: four times as good as as an incandescent and twice as good as the circline. They continue to improve; I just replaced some 13-watt CFLs with new 10-watt ones that are brighter.

Size and Shape

When CFLs came out, they were a big improvement over the circle fluorescent bulb. The first CFLs I used were still larger than incandescent bulbs, for an adequate amount of light. They had U-shaped tubes 5 or 6 inches long, and the ballast bases were also large, at least 2 inches wide. So they fit into many light fixtures, but certainly not all. After a few years the spiral-shaped bulbs became popular, and are now the predominant form.

My solutions:

• Use them where they fit. If a fixture didn't have enough room, I left it alone, waiting for future improved CFLs to fit.
• Try different CFLs. It seems like every one of them is a a little different size and shape. Swap around the ones you already have. Search the stores or online retailers for smaller sizes.
• Buy light fixtures with more room. Some fixtures will hide variations in bulb size and shape better than others. During house renovation, I look for fixtures with various features:
  • Frosted glass rather than clear.
  • Larger glass domes or shades rather than individual ones.
  • Standard (E26) base rather than small (E12 candelabra) base.

Start Time

Incandescent bulbs generally turn on at full brightness instantly. Many, if not most, CFLs do not. Nearly all that I have tried have had some variation of a warm-up period. Some of them come on instantly but dim, and take 60 to 90 seconds to become fully bright. Some of them have a delay of 1 or 2 seconds and then come on at full brightness. Some new CFLs now come on nearly instantly at nearly full brightness, but certainly not all. One would expect you could get used to it over time, but even after 10 years I still find it disorienting to turn on the switch and not have light right away.

My solutions:

• Get used to it. The simplest choice, but not popular with the family.
• Use multi-bulb fixtures where possible. Two 10-watt bulbs are better than one 20-watt bulb, because you can mix types of bulbs.
• Combine CFLs with incandescents. In multi-bulb fixtures, keep at least one incandescent for instant light. In two-bulb fixtures, this gives you only a 25% savings instead of a potential 75% savings. But it was my only choice with the earliest CFLs, and is better than no savings.
• Combine different CFLs. This is the best choice where possible. If you have a few instant start CFLs, mix them in fixtures with delay-start or dim-start CFLs. If you don't have any instant-start ones that fit, at least combine the delay-start and dim-start bulbs. You'll at least have some light to see for the first second or so.

I had one bathroom light with six sockets behind a long glass diffuser. This was ideal for mixing and matching various CFLs. As one of the earliest fixtures I changed, it had a variety of CFLs, each with a slightly different start delay. It was almost entertaining turning on the light switch and watching them blink on in sequence.

Problem Light Fixtures

Some light fixtures lend themselves to CFLs better than others. Ones with 2 or 3 sockets behind a big glass bowl are ideal. Others are not so accommodating.

• Individual glass shades which open downward.
  
  CFL fan bulb
  Some light fixtures have separate glass shades for each socket, and open downward so that you are looking right at the bulb. It is easier if the light is wall-mounted, so you are looking more at the side of the shade rather than the opening. But if it is overhead on an 8-foot high ceiling or even hanging lower, appearance may be an issue. On one low ceiling fan with 3 short glass shades, not even the smallest spiral CFL looked as good as the short incandescent fan bulbs. After much searching, I found a perfect fit in the Lights of America A16 fan bulb at ESP Lighting. They are dim-start bulbs, but working adequately.
• 
  Torpedo candelabra CFL
  Porchlight with clear glass and three candelabra-base sockets. This one needs to produce a lot of light (at least 75 to 100 watt equivalent) and so I kept the incandescent bulbs until this year. In the past I could only find very low wattage candelabra-base CFLs, using 3 watts and producing the equivalent of a 10 or 15 watt incandescent. I recently found higher wattage candelabra-based bulbs which worked. I selected 9-watt "torpedo-shape" bulbs from EFI with excellent results. Three of these 9-watt CFLs produce more than enough light.
• 
  Chandelier
  Candelabra-base chandelier. This is the last problem light fixture in the house. It has six candelabra-base sockets, with individual lamp shades that clip on to the bulbs. Because it is in the dining room, it needs to produce a lot of light. Right now it has 3 incandescent bulbs and 3 CFLs. The CFLs are not very bright, because of their small size to match the incandescents and the shades. In addition, it used to have a dimmer switch, which I removed when I added the CFLs, and my wife isn't happy about that. I'm still looking for a solution.

Despite the various trade-offs, I am very happy with compact fluorescent bulbs. As they continue to improve, these quirks will be forgotten. Until then, I just consider it another fun challenge.