There's nothing worse than bad lighting. Take an otherwise beautiful room and illuminate it with the wrong kind of light - whether too dim, too bright, too hot, too cold, too pale, or too bleak - and the mood, feeling, and livability of the space is ruined. And the worst of the bad-lighting culprits are the cold, bleak, buzzing, latter-generation fluorescents that make you feel like you're trapped in some Soviet-era mental hospital, or the Matrix, or some other world that has forgotten its love for humanity.
From an environmental perspective, of course, using fluorescent lighting, especially the compact fluorescent lighting (CFLs) - the kind developed to replace the screw-in incandescent bulbs - is the absolute right thing to do. Incandescent and halogens lamps use energy like it's going out of style, so much so that a colleague of mine calls then "SUBs" or "Sport Utility Bulbs." The reason is pretty simple: they make light by heating a filament until it glows, with 90 percent of the energy going to heat, and only 10 percent coming out as light. CFLs, on the other hand, produce light by another, mechanism entirely - as is evidenced by the fact that you can touch them when they're on without getting burned - and use about one-thirds to one-quarter of the energy for the same amount of light.
What's more, because you're not torturing a thin piece of metal with high volumes of electricity, CFLs, which don't endure the same stress of intense heat, tend to last about thirteen times longer (about 10,000 to 15,000 hours). Which means if you use your CFL for eight hours a day, it will last for 3-4 years, compared to 3-4 months for the SUBs. In terms of cost, CFLs generally run between $10 and $17, although sometimes you can find deals for as low as $6 or $8. This is compared to the 75 cents for the SUBs, but since CFLs last so long (that's thirteen replacement SUBs you don't have to buy) and save so much energy, they typically pay for themselves within one to two years, depending on how much you use them.
The only problem is that most people associate today's CFLs with the old-school, hideous, depressing fluorescents that somehow still persist in the bleaker corners of society, and hate the very idea of them. But let's be clear, bad lighting is totally counter to the basic principles of green building. Green building is not part of the old school environmentalism where people are asked to suck it up and sacrifice their personal comfort to save Mother Earth. Not that there's anything wrong with a little sacrifice and an overarching respect and awareness of the planet, but if warm, full spectrum energy efficient lighting is available - and improvements in CFL technology have made it so - then the thing to do is understand what makes quality of light good and what makes it bad, and to make sure that you get both the better environmental product and the better lighting product.
When shopping for CFLs, there are essentially three variables to keep in mind: brightness, color, and color rendering. Brightness is the most straightforward of the three. A wide misconception about CFLs is that they are not as bright as their SUB counterparts, but that's only because it's easy to get confused and buy a CFL that isn't as bright as you want. Most people are used to thinking of brightness in terms of watts, since we've been around enough 60, 75, and 100 watt incandescent bulbs to know the difference implicitly. But a watt is a measure of power (rate of energy consumption), not of brightness, and hence it's the wrong unit to use. The unit to pay attention to is "lumens," which actually measures brightness. CFL packages will probably tell you what type of incandescent the CFL replaces, as in: "Use this CFL to replace a 60 watt incandescent bulb."