Fluorescent lighting is a great way to get a lot of light output with relatively little energy usage. While the most common fluorescent bulbs are straight tubes, there are some with other shapes. The main reason for alternate shapes is size constraints. If you only have a 2-foot by 2-foot square, and you need a high amount of light output, then long linear (straight tube) fluorescent bulbs will not work. U-Shaped bulbs, however, would be perfect.
Quite literally, U-Shaped (also referred to as U-Bent or U-Bend) bulbs are straight tubes bent in the middle. There is no functional difference between them technically.
U-Shaped fluorescent bulbs, like all fluorescents, are powered and controlled by ballasts. Ballasts are heavy devices mounted inside of fluorescent light fixtures and connected by wires to the sockets. When a fluorescent bulb is placed in the fixture, it creates a connection between the two sockets and the energy flowing through the bulb, which in turn causes the phosphors on the inside of the bulb to glow with visible light. Even though U-Shaped bulbs have two bases pointing the same direction, the concept of the bulb works the same as the straight tube.
U-Shaped bulbs are available from all major lighting manufacturers: Osram Sylvania, GE (General Electric), Philips, and Westinghouse. They come in T8 and T12 as well as Standard and High Output designs. U-Shaped bulbs are generally listed as Rapid Start. This means that the bulbs will light up within mere moments of the light switch being turn on.
The attention to detail given by architects, office designers, and contractors demands many choices in lighting. Manufacturers knew that people would need more color choices with fluorescent bulbs than just warm white and cool white. You can find color temperatures of 3000K or 30K (warm white), 3500K or 35K (warm/cool blend), 4100K opr 41K (cool white), 5000K or 50K (pure white), and 6500K or 65K (full spectrum / daylight). You can fit almost any mood you wish with these bulbs.
The very latest enhancement to T8 bulbs is the eco-friendly design. According to Sylvania, "Ecologic is a comprehensive program focused on addressing environmental issues at all stages of lamp life." They go on to say that bulbs in this category "are designed to meet the Federal Toxicity Characteristic Leaching Procedure (TCLP) criteria for classification as non-hazardous waste in most states." The U-Shaped bulbs friendliest to our environment will be listed with 'ECO' on the description.