If you are thinking about a fluorescent light upgrade, we have some useful information for you. T-12 tube bulbs have been used in fluorescent light fixtures for garages and workshops, but a variety of energy-saving T-8 bulbs are available and will snap right into the older lights.
If you want different levels of light or energy savings, consider changing the bulbs. The energy savings is only 8 watts per bulb (40W to 32W) but if you use them for many hours, the savings will add up over time.
If you have an older fixture with an older ballast, that might be a problem. Unless you have a ballast that is compatible with T-8, the new bulbs will burn out too quickly. Replacing a ballast can be expensive, and sometimes it can even cost more than a new light fixture. And, it will require some time and electrical skills to remove the old ballast and install a new one.
If that is your situation, you have a couple of choices: stay with what you have and keep using T-12 bulbs and ballast, or replace the whole light fixture. If there are other concerns, like an irritating hum from the fixture, it is probably time to replace the fixture. When you shop for a new one, take a good look at the LED options available. You might just decide to stop using fluorescent all together.
If you need more information, let us know. We are always glad to help.